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Advanced access layer to PostgreSQL via promises

pg-promise

Advanced access layer tonode-postgres via Promises/A+ .

Advanced access layer to PostgreSQL via promises Advanced access layer to PostgreSQL via promises Advanced access layer to PostgreSQL via promises Advanced access layer to PostgreSQL via promises

Advanced access layer to PostgreSQL via promises

  • SupportingPromise, Bluebird , When ,Q, etc.
  • Transactions, functions, flexible query formatting;
  • Automatic database connections;
  • Strict query result filters.
  • About
  • Installing
  • Getting Started
    • Initialization
    • Connection
    • Documentation
  • Testing
  • Usage
    • Queries and Parameters
      • Raw Text
      • Open Values
      • SQL Names
    • Query Result Mask
    • Named Parameters
    • Conversion Helpers
    • Custom Type Formatting
      • Raw Custom Types
    • Query Files
    • Connections
      • Detached Connections
      • Shared Connections
      • Tasks
    • Transactions
      • Detached Transactions
      • Shared-connection Transactions
      • Nested Transactions
      • Synchronous Transactions
      • Configurable Transactions
    • Generators
  • Advanced
    • Initialization Options
    • Library de-initialization
  • History
  • License

About

Built on top ofnode-postgres and its connection pool, this library translates their callback interface into one based on Promises/A+ , while extending the protocol to a higher level, with automated connections and transactions management.

In addition, the library provides:

  • its own, more flexible query formatting;
  • event reporting for connectivity, errors, queries and transactions;
  • support for all popular promise libraries + ES6 generators;
  • declarative approach to controlling query results.

Installing

$ npm install pg-promise 

Getting Started

Initialization

Loading and initializing the library withInitialization Options:

var pgp = require('pg-promise')({     // Initialization Options });

− or withoutInitialization Options:

var pgp = require('pg-promise')();

Connection

Use one of the two ways to specify database connection details:

  • Configuration Object:
var cn = {     host: 'localhost', // server name or IP address;     port: 5432,     database: 'my_db_name',     user: 'user_name',     password: 'user_password' };
  • Connection String:
var cn = 'postgres://username:password@host:port/database';

Create a global/shared database object from the connection details:

var db = pgp(cn);

Object db represents the database protocol, with lazy database connection, i.e. only the actual query methods acquire and release the connection. Therefore, you should create only one global/shared db object per connection details.

Use of a configuration object has the benefit of being changeable: it is used by the library directly, and changing properties of the original object will reconnect with the next query.

This library does not use any of the connection’s details, it simply passes them on toPG when opening a connection. For more details see pg connection parameters inWiKi andimplementation.

API: Database .

Documentation

Learn by Example is the quickest way to get started with this library, while the current document details most of the basic functionality this library provides.

If you are writing in TypeScript, see/typescript.

For the protocol see the API Documentation , and for everything else -Wiki pages.

Testing

  • Clone the repository (or download, if you prefer):
$ git clone https://github.com/vitaly-t/pg-promise 
  • Install the library’s DEV dependencies:
$ npm install 
  • Make sure all tests can connect to your local test database, using the connection details intest/db/header.js. Either set up your test database accordingly or change the connection details in that file.

  • Initialize the database with some test data:

$ node test/db/init.js 
  • To run all tests:
$ npm test 
  • To run all tests with coverage:
$ npm run coverage 

Usage

Queries and Parameters

Every connection context of the library shares the same query protocol, starting with generic method query , defined as shown below:

function query(query, values, qrm);
  • query (required) – a string with support for three types of formatting, depending on the values passed:
    • format $1 (single variable), if values is of type string , boolean , number , Date , function or null ;
    • format $1, $2, etc.. , if values is an array;
    • format $*propName* , if values is an object (not null and not Date ), where * is any of the supported open-close pairs: {} , () , <> , [] , // ;
  • values (optional) – value/array/object to replace the variables in the query;
  • qrm – (optional) Query Result Mask , as explained below. When not passed, it defaults to pgp.queryResult.any .

When a value/property inside array/object is an array, it is treated as a PostgreSQL Array Type , converted into the array constructor format of array[] , the same as calling method pgp.as.array() .

When a value/property inside array/object is of type object (except for null , Date or Buffer ), it is automatically serialized into JSON, the same as calling method pgp.as.json() , except the latter would convert anything to JSON.

For the most current SQL formatting support see method as.format

Raw Text

Raw-text values can be injected by ending the variable name with ^ or :raw : $1^, $2^, etc... , $*varName^* , where * is any of the supported open-close pairs: {} , () , <> , [] , //

Raw text is injected without any pre-processing, which means:

  • No proper escaping (replacing each single-quote symbol ' with two);
  • No wrapping text into single quotes.

Unlike regular variables, value for raw-text variables cannot be null or undefined , because of the ambiguous meaning in this case. If such values are passed in, the formatter will throw error Values null/undefined cannot be used as raw text.

Special syntax this^ within theNamed Parametersrefers to the formatting object itself, to be injected as a raw-text JSON-formatted string.

For the most current SQL formatting support see method as.format

Open Values

Open values simplify concatenation of string values within a query, primarily for such special cases as LIKE / ILIKE filters.

Names for open-value variables end with either :value or symbol # , and it means that such a value is to be properly formatted and escaped, but not to be wrapped in quotes when it is a text.

Similar toraw-textvariables, open-value variables are also not allowed to be null or undefined , or they will throw error Open values cannot be null or undefined. And the difference is thatraw-textvariables are not escaped, while open-value variables are properly escaped.

Below is an example of formatting LIKE filter that ends with a second name:

// using $1# or $1:value syntax: query("...WHERE name LIKE '%$1#'", "O'Connor"); query("...WHERE name LIKE '%$1:value'", "O'Connor"); //=> ...WHERE name LIKE '%O''Connor'  // using ${propName#} or ${propName:value} syntax: query("...WHERE name LIKE '%${filter#}'", {filter: "O'Connor"}); query("...WHERE name LIKE '%${filter:value}'", {filter: "O'Connor"}); //=> ...WHERE name LIKE '%O''Connor'

See also: method as.value .

SQL Names

When a variable ends with ~ (tilde) or :name , it represents an SQL name or identifier, which must be a text string of at least 1 character long. Such name is then properly escaped and wrapped in double quotes.

query('INSERT INTO $1~($2~) VALUES(...)', ['Table Name', 'Column Name']); // => INSERT INTO "Table Name"("Column Name") VALUES(...)  // A mixed example for a dynamic column list: var columns = ['id', 'message']; query('SELECT ${columns^} FROM ${table~}', {     columns: columns.map(pgp.as.name).join(),     table: 'Table Name' }); // => SELECT "id","message" FROM "Table Name"

Relying on this type of formatting for sql names and identifiers, along with regular variable formatting makes your application impervious to sql injection.

See methods: as.name , as.format

Query Result Mask

In order to eliminate the chances of unexpected query results and thus make the code more robust, method query uses parameter qrm (Query Result Mask):

/////////////////////////////////////////////////////// // Query Result Mask flags; // // Any combination is supported, except for one + many. var queryResult = {     /** Single row is expected. */     one: 1,     /** One or more rows expected. */     many: 2,     /** Expecting no rows. */     none: 4,     /** many|none - any result is expected. */     any: 6 };

In the following generic-query example we indicate that the call can return anything:

db.query('select * from users');

which is equivalent to making one of the following calls:

var qrm = pgp.queryResult; db.query('select * from users', undefined, qrm.many | qrm.none); db.query('select * from users', undefined, qrm.any); db.manyOrNone('select * from users'); db.any('select * from users');

This usage pattern is facilitated through result-specific methods that can be used instead of the generic query:

db.many(query, values); // expects one or more rows db.one(query, values); // expects a single row db.none(query, values); // expects no rows db.any(query, values); // expects anything, same as `manyOrNone` db.oneOrNone(query, values); // expects 1 or 0 rows db.manyOrNone(query, values); // expects anything, same as `any`

There is however one specific method result(query, values) to bypass any result verification, and instead resolve with the originalResult object passed from thePG library.

You can also add your own methods and properties to this protocol via theextendevent.

Each query function resolves its data according to the qrm that was used:

  • nonedata is undefined . If the query returns any kind of data, it is rejected.
  • onedata is a single object. If the query returns no data or more than one row of data, it is rejected.
  • manydata is an array of objects. If the query returns no rows, it is rejected.
  • one | nonedata is null , if no data was returned; or a single object, if one row was returned. If the query returns more than one row of data, the query is rejected.
  • many | nonedata is an array of objects. When no rows are returned, data is an empty array.

If you try to specify one | many in the same query, such query will be rejected without executing it, telling you that such mask is invalid.

If qrm is not specified when calling generic query method, it is assumed to be many | none = any , i.e. any kind of data expected.

This is all about writing robust code, when the client specifies what kind of data it is ready to handle on the declarative level, leaving the burden of all extra checks to the library.

Named Parameters

The library supports named parameters in query formatting, with the syntax of $*propName* , where * is any of the following open-close pairs: {} , () , <> , [] , //

db.query('select * from users where name=${name} and active=$/active/', {     name: 'John',     active: true });

The same goes for all types of query methods as well as method as.format , where values can also be an object whose properties can be referred to by name from within the query.

A valid property name consists of any combination of letters, digits, underscores or $ , and they are case-sensitive. Leading and trailing spaces around property names are ignored.

It is important to know that while property values null and undefined are both formatted as null , an error is thrown when the property doesn’t exist at all (except for partial replacements – see below).

You can also use partial replacements within method as.format , to ignore variables that do not exist in the formatting object.

this reference

Property this is a reference to the formatting object itself, so it can be inserted as a JSON-formatted string, alongside its properties.

  • ${this} – inserts the object itself as a JSON-formatted string;
  • ${this^} – inserts the object itself as a raw-text JSON-formatted string.

example:

var doc = {     id: 123,     body: "some text" };  db.none("INSERT INTO documents(id, doc) VALUES(${id}, ${this})", doc)     .then(function () {         // success;     })     .catch(function (error) {         // error;     });

which will execute:

INSERT INTO documents(id, doc) VALUES(123, '{"id":123,"body":"some text"}') 

Version 3.2.1 and later allows syntax :json as an alternative to formatting the value as a JSON string.

NOTE:Technically, it is possible in javascript, though not recommended, for an object to contain a property with name this . And in such cases the property’s value will be used instead.

Functions and Procedures

In PostgreSQL stored procedures are just functions that usually do not return anything.

Suppose we want to call function findAudit to find audit records by user_id and maximum timestamp. We can make such call as shown below:

db.func('findAudit', [123, new Date()])     .then(function (data) {         console.log(data); // printing the data returned     })     .catch(function (error) {         console.log(error); // printing the error     });

We passed it user_id = 123 , plus current Date/Time as the timestamp. We assume that the function signature matches the parameters that we passed. All values passed are serialized automatically to comply with PostgreSQL type formats.

Method func accepts optional third parameter – qrm (Query Result Mask), the same as method query .

And when you are not expecting any return results, call db.proc instead. Both methods return aPromise object, but db.proc doesn’t take a qrm parameter, always assuming it is one | none .

Summary for supporting procedures and functions:

  • func(query, values, qrm) – expects the result according to qrm
  • proc(query, values) – calls func(query, values, qrm.one | qrm.none)

Conversion Helpers

The library provides several helper functions to convert javascript types into their proper PostgreSQL presentation that can be passed directly into queries or functions as parameters. All of such helper functions are located within namespace pgp.as , and each function returns a formatted string when successful or throws an error when it fails.

Custom Type Formatting

When we pass values as a single parameter or inside an array, it is verified to be an object that supports function formatDBType , as either its own or inherited. And if the function exists, its return result overrides both the actual value and the formatting syntax for parameter query .

This allows use of your own custom types as formatting parameters for the queries, as well as overriding formatting for standard object types, such as Date and Array .

Example: your own type formatting

function Money(m) {     this.amount = m;     this.formatDBType = function () {         // return a string with 2 decimal points;         return this.amount.toFixed(2);     } }

Example: overriding standard types

Date.prototype.formatDBType = function () {     // format Date as a local timestamp;     return this.getTime(); };

Function formatDBType is allowed to return absolutely anything, including:

  • instance of another object that supports its own custom formatting;
  • instance of another object that doesn’t have its own custom formatting;
  • another function, with recursion of any depth;

Please note that the return result from formatDBType may even affect the formatting syntax expected within parameter query , as explained below.

If you pass in values as an object that has function formatDBType , and that function returns an array, then your query is expected to use $1, $2 as the formatting syntax.

And if formatDBType in that case returns a custom-type object that doesn’t support custom formatting, then query will be expected to use $*propName* as the formatting syntax.

Raw Custom Types

This features allows overriding raw flag for the values returned from custom types.

Any custom type or standard type that implements function formatDBType can also set property _rawDBType = true to force raw variable formatting on the returned value.

This makes the custom type formatting ultimately flexible, as there is no limitation as to how a custom type can format its value.

For example, some special types, like UUID, do not have natural presentation in JavaScript, so they have to be converted into text strings when passed into the query formatting. For an array of UUID-s, for instance, you would have to explicitly cast the formatted value with ::uuid[] appended at the end of the variable.

You can implement your own presentation for UUID that does not require extra casting:

function UUID(value) {     this.uuid = value;     this._rawDBType = true; // force raw format on output;     this.formatDBType = function () {         // alternatively, you can set flag         // _rawDBType during this call:         // this._rawDBType = true;         return this.uuid;     }; }

When you chain one custom-formatting type to return another one, please note that setting _rawDBType on any level will set the flag for the entire chain.

Query Files

Use of external SQL files (via QueryFile ) has the following advantages:

  • Much cleaner JavaScript code, with all SQL kept in external files;
  • Much easier to write large and well-formatted SQL, with comments and whole revisions;
  • Changes in external SQL can be automatically re-loaded, without restarting the app.

Example:

// Helper for linking to external query files:  function sql(file) {     return new pgp.QueryFile(file, {minify: true}); }  // Create QueryFile globally, once per file: var sqlFindUser = sql('./sql/findUser.sql');  db.one(sqlFindUser, {id: 123})     .then(user=> {         console.log(user);     })     .catch(error=> {         if (error instanceof pgp.errors.QueryFileError) {             // => the error is related to our QueryFile         }     });

File findUser.sql :

/*     multi-line comment */ SELECT name, dob -- single-line comment FROM Users WHERE id = ${id}

Every query method of the library can accept type QueryFile as its query parameter. The type never throws any error, leaving it for query methods to reject with QueryFileError .

You should only create a single instance of QueryFile per file, and then reuse that instance throughout the application.

Notable features of QueryFile :

  • debug mode, to make every query request check if the file has changed since it was last read, and if so – read it afresh. This way you can write sql queries and see immediate updates without having to restart your application.
  • Option params is for static SQL pre-formatting, to inject certain values only once, like a schema name or a configurable table name.

Connections

The library supports promise-chained queries on shared and detached connections. Choosing which one to use depends on the situation and personal preferences.

Detached Connections

Queries in a detached promise chain maintain connection independently, they each acquire a connection from the pool, execute the query and then release the connection back to the pool.

db.one('select * from users where id = $1', 123) // find the user from id;     .then(function (data) {         // find 'login' records for the user found:         return db.query('select * from audit where event=$1 and userId=$2',             ['login', data.id]);     })     .then(function (data) {         console.log(data); // display found audit records;     })     .catch(function (error) {         console.log(error); // display the error;     });

In a situation where a single request is to be made against the database, a detached chain is the only one that makes sense. And even if you intend to execute multiple queries in a chain, keep in mind that even though each will use its own connection, such will be used from a connection pool, so effectively you end up with the same connection, without any performance penalty.

Shared Connections

NOTE:With the addition ofTasks, use of shared connections directly is considered obsolete. It is recommended that you useTasksinstead, as they are much easier and safer to use.

A promise chain with a shared connection starts with connect() , which acquires a connection from the pool to be shared with all the queries down the promise chain. The connection must be released back to the pool when no longer needed.

var sco; // shared connection object; db.connect()     .then(function (obj) {         sco = obj; // save the connection object;         // find active users created before today:         return sco.query('select * from users where active=$1 and created < $2',             [true, new Date()]);     })     .then(function (data) {         console.log(data); // display all the user details;     })     .catch(function (error) {         console.log(error); // display the error;     })     .finally(function () {         if (sco) {             sco.done(); // release the connection, if it was successful;         }     });

Shared-connection chaining is when you want absolute control over the connection, either because you want to execute lots of queries in one go, or because you like squeezing every bit of performance out of your code. Other than that, the author hasn’t seen any performance difference from the detached-connection chaining. And besides, any long sequence of queries normally resides inside a task or transaction, which always uses shared-connection chaining automatically.

Tasks

A task represents a shared connection to be used within a callback function. The callback can be either a regular function or an ES6 generator.

A transaction, for example, is just a special type of task, wrapped in CONNECT->COMMIT/ROLLBACK .

db.task(function (t) {     // t = this;     // execute a chain of queries; })     .then(function (data) {         // success;     })     .catch(function (error) {         // failed;         });

The purpose of tasks is simply to provide a shared connection context within the callback function to execute and return a promise chain, and then automatically release the connection.

In other words, it is to simplify the use ofshared connections, so instead of calling connect in the beginning and done in the end (if it was connected successfully), one can call db.task instead, execute all queries within the callback and return the result.

Transactions

Transactions can be executed within both shared and detached promise chains in the same way, performing the following actions:

  1. Acquires a new connection (detached chains only);
  2. Executes BEGIN command;
  3. Invokes your callback function (or generator) with the connection object;
  4. Executes COMMIT , if the callback resolves, or ROLLBACK , if the callback rejects;
  5. Releases the connection (detached chains only);
  6. Resolves with the callback result, if success; rejects with the reason, if failed.

Detached Transactions

db.tx(function (t) {     // t = this;     // creating a sequence of transaction queries:     var q1 = this.none('update users set active=$1 where id=$2', [true, 123]);     var q2 = this.one('insert into audit(entity, id) values($1, $2) returning id',         ['users', 123]);      // returning a promise that determines a successful transaction:     return this.batch([q1, q2]); // all of the queries are to be resolved; })     .then(function (data) {         console.log(data); // printing successful transaction output;     })     .catch(function (error) {         console.log(error); // printing the error;     });

A detached transaction acquires a connection and exposes object t = this to let all containing queries execute on the same connection.

Shared-connection Transactions

NOTE:Use of shared-connection transactions is no longer necessary. When a transaction needs to use the connection from its container, you should execute it inside a task instead.

var sco; // shared connection object; db.connect()     .then(function (obj) {         sco = obj;         return sco.oneOrNone('select * from users where active=$1 and id=$1', [true, 123]);     })     .then(function (data) {         return sco.tx(function (t) {             // t = this;             var q1 = this.none('update users set active=$1 where id=$2', [false, data.id]);             var q2 = this.one('insert into audit(entity, id) values($1, $2) returning id',                 ['users', 123]);              // returning a promise that determines a successful transaction:             return this.batch([q1, q2]); // all of the queries are to be resolved;         });     })     .catch(function (error) {         console.log(error); // printing the error;     })     .finally(function () {         if (sco) {             sco.done(); // release the connection, if it was successful;         }     });

If you need to execute just one transaction, the detached transaction pattern is all you need. But even if you need to combine it with other queries in a detached chain, it will work the same. As stated earlier, choosing a shared chain over a detached one is mostly a matter of special requirements and/or personal preference.

Nested Transactions

Similar to the shared-connection transactions, nested transactions automatically share the connection between all levels. This library sets no limitation as to the depth (nesting levels) of transactions supported.

Example:

db.tx(function (t) {     // t = this;     var queries = [         this.none('drop table users;'),         this.none('create table users(id serial not null, name text not null)')     ];     for (var i = 1; i <= 100; i++) {         queries.push(this.none('insert into users(name) values($1)', 'name-' + i));     }     queries.push(         this.tx(function (t1) {             // t1 = this != t;             return this.tx(function (t2) {                 // t2 = this != t1 != t;                 return this.one('select count(*) from users');             });         }));     return this.batch(queries); })     .then(function (data) {         console.log(data); // printing transaction result;     })     .catch(function (error) {         console.log(error); // printing the error;     });

Limitations

It is important to know that PostgreSQL doesn’t have proper support for nested transactions, it only supports partial rollbacks via savepoints inside transactions. The difference between the two techniques is huge, as explained further.

Proper support for nested transactions means that the result of a successful sub-transaction isn’t rolled back when its parent transaction is rolled back. But with PostgreSQL save-points, if you roll-back the top-level transaction, the result of all inner save-points is also rolled back.

Save-points are only good for partial rollbacks , i.e. you can roll-back results of sub-transactions, with yet successful commit for the top-level transaction. Using promises it is easy to construct your transaction so it would utilize that logic. This library automatically provides a transaction on the top level, and save-points for all sub-transactions.

Synchronous Transactions

A regular task/transaction with a set of independent queries relies on method batch to resolve all queries asynchronously.

However, when it comes to executing a significant number of queries during a bulk INSERT or UPDATE , such approach is no longer practical. For one thing, it implies that all requests have been created as promise objects, which isn’t possible when dealing with a huge number of queries, due to memory limitations imposed by NodeJS. And for another, when one query fails, the rest will continue trying to execute, due to their promise nature, as being asynchronous.

This is why within each task/transaction we have method sequence , to be able to execute a strict sequence of queries one by one, and if one fails – the rest won’t try to execute.

function source(index, data, delay) {     // must create and return a promise object dynamically,     // based on the index of the sequence;     switch (index) {         case 0:             return this.query('select 0');         case 1:             return this.query('select 1');         case 2:             return this.query('select 2');     }     // returning or resolving with undefined ends the sequence;     // throwing an error will result in a reject; }  db.tx(function (t) {     // t = this;     return this.sequence(source); })     .then(function (data) {         console.log(data); // print result;     })     .catch(function (error) {         console.log(error); // print the error;     });

Sequence is based on implementation ofspex.sequence.

Configurable Transactions

In order to be able to fine-tune database requests in a highly asynchronous environment, PostgreSQL supports Transaction Snapshots , plus 3 ways of configuring a transaction:

  • SET TRANSACTION , to configure the current transaction, which your can execute as the very first query in your transaction function;
  • SET SESSION CHARACTERISTICS AS TRANSACTION – setting default transaction properties for the entire session;
  • BEGIN + Transaction Mode – initiates a pre-configured transaction.

The first method is quite usable, but that means you have to start every transaction with an initial query to configure the transaction, which can be a bit awkward.

The second approach isn’t very usable within a database framework as this one, which relies on a connection pool, so you don’t really know when a new connection is created.

The last method is not usable, because transactions in this library are automatic, executing BEGIN without your control, or so it was until Transaction Mode type was added (read further).

Transaction Mode extends the BEGIN command in your transaction with a complete set of configuration parameters.

var TransactionMode = pgp.txMode.TransactionMode; var isolationLevel = pgp.txMode.isolationLevel;  // Create a reusable transaction mode (serializable + read-only + deferrable): var tmSRD = new TransactionMode({     tiLevel: isolationLevel.serializable,     readOnly: true,     deferrable: true });  function myTransaction() {     return this.query('SELECT * FROM table'); }  myTransaction.txMode = tmSRD; // assign transaction mode;  db.tx(myTransaction)     .then(function(){         // success;     });

Instead of the default BEGIN , such transaction will initiate with the following command:

BEGIN ISOLATION LEVEL SERIALIZABLE READ ONLY DEFERRABLE 

Transaction Mode is set via property txMode on the transaction function.

This is the most efficient and best-performing way of configuring transactions. In combination with Transaction Snapshots you can make the most out of transactions in terms of performance and concurrency.

Generators

If you prefer writing asynchronous code in a synchronous manner, you can implement your tasks and transactions as generators.

function * getUser(t) {     // t = this;     let user = yield this.oneOrNone('select * from users where id = $1', 123);     return yield user || this.one('insert into users(name) values($1) returning *', 'John'); }  db.task(getUser)     .then(function (user) {         // success;     })     .catch(function (error) {         // error;     });

The library verifies whether the callback function is a generator, and executes it accordingly.

Advanced

Initialization Options

When initializing the library, you can pass object options with a set of global properties. See API / options for complete list of supported options.

pgFormatting

By default, pg-promise provides its own implementation of the query formatting, as explained inQueries and Parameters.

If, however, you want your queries formatted by thePG library, set parameter pgFormatting to be true when initializing the library, and every query formatting will redirect to thePG’s implementation.

Although this has a huge implication to the library’s functionality, it is not within the scope of this project to detail. For any further reference you should use documentation of thePG library.

Note the following formatting features implemented bypg-promise that are not innode-postgres:

  • Custom Type Formatting
  • Single-value formatting:pg-promise doesn’t require use of an array when passing a single value;
  • Raw-Text support: injecting raw/pre-formatted text values into the query;
  • Functions as formatting parameters, with the actual values returned from the callbacks;
  • PostgreSQL Array Constructors are used when formatting arrays, not the old string syntax;
  • Automatic conversion of numeric NaN , +Infinity and -Infinity into their string presentation;
  • Support forthis reference;

NOTE:Formatting parameters for calling functions (methods func and proc ) is not affected by this override. When needed, use the generic query instead to invoke functions with redirected query formatting.

promiseLib

By default, pg-promise uses ES6 Promise. If your version of NodeJS doesn’t support ES6 Promise, or you want a different promise library to be used, set this property to the library’s instance.

Example of switching over toBluebird:

var promise = require('bluebird'); var options = {     promiseLib: promise }; var pgp = require('pg-promise')(options);

Promises/A+ libraries that implement a recognizable promise signature and work automatically:

  • ES6 Promise – used by default, though it doesn’t have done() or finally() .
  • Bluebird – best alternative all around;
  • Promise – very solid library;
  • When – quite old, not the best support;
  • Q – most widely used;
  • RSVP – doesn’t have done() , use finally/catch instead
  • Lie – doesn’t have done() .

If you pass in a library that doesn’t implement a recognizable promise signature, pg-promise will throw error Invalid promise library specified. during initialization.

For such libraries you can usePromise Adapter to make them compatible with pg-promise , mostly needed by smaller and simplified Conformant Implementations .

Library de-initialization

When exiting your application, you can make the following call:

pgp.end();

This will releasepg connection pool globally and make sure that the process terminates without any delay. If you do not call it, your process may be waiting for 30 seconds (default forpoolIdleTimeout), waiting for the connection to expire in the pool.

If, however you normally exit your application by killing the NodeJS process, then you don’t need to use it.

History

  • 4.1.0 Adding helpers namespace with additional query-formatting methods. Released: May 12, 2016
  • 4.0.0 Consolidating the entire error-reporting mechanism. Released: April 24, 2016
  • 3.9.0 Prepared Statements support rewritten, adding new type PreparedStatement . Released: April 20, 2016
  • 3.8.0 Added Database Context support (see Database ). Released: April 14, 2016
  • 3.7.1 Adding internal typescript support to the library. Released: April 10, 2016
  • 3.7.0 Modifying the protocol to accommodate changes in pg 4.5.3 for isolatedNative Bindings. Released: April 9, 2016
  • 3.6.0 Extending QueryResultError for better diagnostics. Released: April 8, 2016
  • 3.5.0 Adding support forNative Bindings. Released: April 06, 2016
  • 3.4.0 Adding support forOpen Valuesand type Buffer . Released: March 20, 2016
  • 3.3.0 Adding strict variable requirement to $1, $2,... formatting. Released: March 05, 2016
  • 3.2.1 Adding support for formatting overrides: :raw , :name , :json and :csv . Released: February 22, 2016
  • 3.2.0 Adding formatting options support, specifically option partial , add its use withinQuery Files. Released: February 20, 2016
  • 3.1.0 Adding support for [SQL Names]. Released: January 27, 2016
  • 3.0.3 Complete replacement of the API with GitHub-hosted one. Released: January 21, 2016
  • 2.9.3 Replaced all SQL processing withpg-minify dependency. Released: January 20, 2016
  • 2.9.1 added custom SQL parser for external files. Released: January 19, 2016
  • 2.9.0 added support forQuery Files. Released: January 18, 2016
  • 2.8.0 added support forevent receive. Released: December 14, 2015
  • 2.6.0 added support forES6 Generators. Released: November 30, 2015
  • 2.5.0 added support forConfigurable Transactions. Released: November 26, 2015
  • 2.4.0 library re-organized for better documentation and easier maintenance. Released: November 24, 2015
  • 2.2.0 major rework on the nested transactions support. Released: October 23, 2015
  • 2.0.8 added all the long-outstanding breaking changes . Released: October 12, 2015
  • 1.11.0 addednoLockinginitialization option. Released: September 30, 2015.
  • 1.10.3 added enforced locks on every level of the library. Released: September 11, 2015.
  • 1.10.0 added support for batch execution within tasks and transactions. Released: September 10, 2015.
  • 1.9.5 added support forRaw Custom Types. Released: August 30, 2015.
  • 1.9.3 added support forCustom Type Formatting. Released: August 30, 2015.
  • 1.9.0 added support forTasks+ initialjsDoc support. Released: August 21, 2015.
  • 1.8.2 added support forPrepared Statements. Released: August 01, 2015.
  • 1.8.0 added support for Query Streaming vianode-pg-query-stream. Released: July 23, 2015.
  • 1.7.2 significant code refactoring and optimizations; added support for super-massive transactions. Released: June 27, 2015.
  • 1.6.0 major update for the test platform + adding coverage. Released: June 19, 2015.
  • 1.5.0 major changes in architecture and query formatting. Released: June 14, 2015.
  • 1.4.0 added this context to all callbacks where applicable. Released: May 31, 2015.
  • 1.3.1 extendedNamed Parameterssyntax to support {} , () , [] , <> and // . Released: May 24, 2015.
  • 1.3.0 much improved error handling and reporting. Released: May 23, 2015.
  • 1.2.0 extendedNamed Parameterssyntax with $(varName) . Released: May 16, 2015.
  • 1.1.0 added support for functions as parameters. Released: April 3, 2015.
  • 1.0.5 added strict query sequencing for transactions. Released: April 26, 2015.
  • 1.0.3 added method queryRaw(query, values) . Released: April 19, 2015.
  • 1.0.1 improved error reporting for queries. Released: April 18, 2015.
  • 1.0.0 official release milestone. Released: April 17, 2015.
  • 0.9.8 added native json support, extended numeric support for NaN , +Infinity and -Infinity . Released: April 16, 2015.
  • 0.9.7 received support for protocol extensibility. Released: April 15, 2015.
  • 0.9.5 received support for raw-text variables. Released: April 12, 2015.
  • 0.9.2 received support for PostgreSQL Array Types. Released: April 8, 2015.
  • 0.9.0 changed the notification protocol. Released: April 7, 2015.
  • 0.8.4 added support for error notifications. Released: April 6, 2015.
  • 0.8.0 added support for named-parameter formatting. Released: April 3, 2015.
  • 0.7.0 fixes the way as.format works (breaking change). Released: April 2, 2015.
  • 0.6.2 has good database test coverage. Released: March 28, 2015.
  • 0.5.6 introduces support for nested transaction. Released: March 22, 2015.
  • 0.5.3 – minor changes; March 14, 2015.
  • 0.5.1 included wider support for alternative promise libraries. Released: March 12, 2015.
  • 0.5.0 introduces many new features and fixes, such as properties pgFormatting and promiseLib . Released on March 11, 2015.
  • 0.4.9 represents a solid code base, backed up by comprehensive testing. Released on March 10, 2015.
  • 0.4.0 is a complete rewrite of most of the library, made first available on March 8, 2015.
  • 0.2.0 introduced on March 6th, 2015, supporting multiple databases.
  • 0.1.4 first release. March 5th, 2015.
  • 0.0.1 initial draft. March 3rd, 2015.

License

Copyright (c) 2016 Vitaly Tomilov ( vitaly.tomilov@gmail.com )

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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