A battle-tested PostgreSQL client with strict types, detail logging and assertions.
- Convenience methods with built-in assertions.
- Middleware support.
- SQL injection guarding.
- Set interpolation.
- Detail logging.
- Parsing and logging of the auto_explain logs.
- Built-in asynchronous stack trace resolution.
- Safe connection pooling.
- Flow types.
- Mapped errors.
- Transactions.
- Atom plugin.
- ESLint plugin.
- Slonik
Use createPool to create a connection pool, e.g.
import {
createPool
} from 'slonik';
const pool = createPool('postgres://');Instance of Slonik connection pool can be then used to create a new connection, e.g.
pool.connect(async (connection) => {
await connection.query(sql`SELECT 1`);
});The connection will be kept alive until the promise resolves (the result of the method supplied to connect()).
Refer to query method documentation to learn about the connection methods.
If you do not require having a persistent connection to the same backend, then you can directly use pool to run queries, e.g.
pool.query(sql`SELECT 1`);Beware that in the latter example, the connection picked to execute the query is a random connection from the connection pool, i.e. using the latter method (without explicit connect()) does not guarantee that multiple queries will refer to the same backend.
createPool(
connectionConfiguration: DatabaseConfigurationType,
clientConfiguration: ClientConfigurationType
): DatabasePoolType;
type DatabaseConnectionUriType = string;
type DatabaseConfigurationType =
DatabaseConnectionUriType |
{|
+database?: string,
+host?: string,
+idleTimeoutMillis?: number,
+max?: number,
+password?: string,
+port?: number,
+user?: string
|};
/**
* @property interceptors An array of [Slonik interceptors](https://github.com/gajus/slonik#slonik-interceptors).
*/
type ClientConfigurationType = {|
+interceptors?: $ReadOnlyArray<InterceptorType>
|};Example:
import {
createPool
} from 'slonik';
const pool = createPool('postgres://localhost');
await pool.query(sql`SELECT 1`);Slonik only allows to check out a connection for the duration of the promise routine supplied to the pool#connect() method.
import {
createPool
} from 'slonik';
const pool = createPool('postgres://localhost');
const result = await pool.connect(async (connection) => {
await connection.query(sql`SELECT 1`);
await connection.query(sql`SELECT 2`);
return 'foo';
});
result;
// 'foo'Connection is released back to the pool after the promise produced by the function supplied to connect() method is either resolved or rejected.
The primary reason for implementing only this connection pooling method is because the alternative is inherently unsafe, e.g.
// Note: This example is using unsupported API.
const main = async () => {
const connection = await pool.connect();
await connection.query(sql`SELECT produce_error()`);
await connection.release();
};In this example, the error causes early rejection of the promise and a hanging connection. A fix to the above is to ensure that connection#release() is always called, i.e.
// Note: This example is using unsupported API.
const main = async () => {
const connection = await pool.connect();
let lastExecutionResult;
try {
lastExecutionResult = await connection.query(sql`SELECT produce_error()`);
} finally {
await connection.release();
}
return lastExecutionResult;
};Slonik abstracts the latter pattern into pool#connect() method.
Functionality can be added to Slonik client by adding interceptors (middleware).
Interceptors are configured using client configuration, e.g.
import {
createPool
} from 'slonik';
const interceptors = [];
const connection = createPool('postgres://', {
interceptors
});Interceptors are executed in the order they are added.
Interceptors implement methods that are used to change the behaviour of the database client at different stages of the connection life-cycle:
type InterceptorType = {|
+afterPoolConnection?: (connection: DatabasePoolConnectionType) => MaybePromiseType<void>,
+afterQueryExecution?: (
queryExecutionContext: QueryExecutionContextType,
query: QueryType,
result: QueryResultType<QueryResultRowType>
) => MaybePromiseType<QueryResultType<QueryResultRowType>>,
+beforePoolConnectionRelease?: (connection: DatabasePoolConnectionType) => MaybePromiseType<void>,
+beforeQueryExecution?: (
queryExecutionContext: QueryExecutionContextType,
query: QueryType
) => MaybePromiseType<QueryResultType<QueryResultRowType>> | MaybePromiseType<void>,
+transformQuery?: (
queryExecutionContext: QueryExecutionContextType,
query: QueryType
) => MaybePromiseType<QueryType>
|};Executed after a connection is acquired from the connection pool (or a new connection is created), e.g.
const pool = createPool('postgres://');
// Interceptor is executed here. ↓
pool.connect();afterQueryExecution must return the result of the query, which will be passed down to the client.
Use afterQuery to modify the query result.
This function can optionally return a direct result of the query which will cause the actual query never to be executed.
Executed before connection is released back to the connection pool, e.g.
const pool = await createPool('postgres://');
pool.connect(async () => {
await 1;
// Interceptor is executed here. ↓
});Executed before beforeQueryExecution.
Transforms query.
createFormatFieldNameInterceptor creates an interceptor that formats query result field names.
This interceptor removes the necessity to alias field names, e.g.
connection.any(sql`
SELECT
id,
full_name "fullName"
FROM person
`);Field name formatter uses afterQuery interceptor to format field names.
/**
* @property format The only supported format is CAMEL_CASE.
* @property test Tests whether the field should be formatted. The default behaviour is to include all fields that match ^[a-z0-9_]+$ regex.
*/
type ConfigurationType = {|
+format: 'CAMEL_CASE',
+test: (field: FieldType) => boolean
|};
(configuration: ConfigurationType) => InterceptorType;import {
createFieldNameTransformationInterceptor,
createPool
} from 'slonik';
const interceptors = [
createFieldNameTransformationInterceptor({
format: 'CAMEL_CASE'
})
];
const connection = createPool('postgres://', {
interceptors
});
connection.any(sql`
SELECT
id,
full_name
FROM person
`);
// [
// {
// id: 1,
// fullName: 1
// }
// ]Normalizes the query.
/**
* @property stripComments Strips comments from the query (default: true).
*/
type ConfigurationType = {|
+stripComments?: boolean
|};
(configuration?: ConfigurationType) => InterceptorType;executionTime log property describes how long it took for the client to execute the query, i.e. it includes the overhead of waiting for a connection and the network latency, among other things. However, it is possible to get the real query execution time by using auto_explain module.
There are several pre-requisites:
-- Load the extension.
LOAD 'auto_explain';
-- or (if you are using AWS RDS):
LOAD '$libdir/plugins/auto_explain';
-- Enable logging of all queries.
SET auto_explain.log_analyze=true;
SET auto_explain.log_format=json;
SET auto_explain.log_min_duration=0;
SET auto_explain.log_timing=true;
-- Enables Slonik to capture auto_explain logs.
SET client_min_messages=log;
This can be configured using afterPoolConnection interceptor, e.g.
const pool = await createPool('postgres://localhost', {
interceptors: [
{
afterPoolConnection: async (connection) => {
await connection.query(sql`LOAD 'auto_explain'`);
await connection.query(sql`SET auto_explain.log_analyze=true`);
await connection.query(sql`SET auto_explain.log_format=json`);
await connection.query(sql`SET auto_explain.log_min_duration=0`);
await connection.query(sql`SET auto_explain.log_timing=true`);
await connection.query(sql`SET client_min_messages=log`);
}
}
]
});Slonik recognises and parses the auto_explain JSON message; Roarr logger will produce a pretty-print of the explain output, e.g.
[2018-12-31T21:15:21.010Z] INFO (30) (@slonik): notice message
notice:
level: notice
message:
Query Text: SELECT count(*) FROM actor
Plan:
Node Type: Aggregate
Strategy: Plain
Partial Mode: Simple
Parallel Aware: false
Startup Cost: 4051.33
Total Cost: 4051.34
Plan Rows: 1
Plan Width: 8
Actual Startup Time: 26.791
Actual Total Time: 26.791
Actual Rows: 1
Actual Loops: 1
Plans:
-
Node Type: Seq Scan
Parent Relationship: Outer
Parallel Aware: false
Relation Name: actor
Alias: actor
Startup Cost: 0
Total Cost: 3561.86
Plan Rows: 195786
Plan Width: 0
Actual Startup Time: 0.132
Actual Total Time: 15.29
Actual Rows: 195786
Actual Loops: 1
sql.raw can be used to generate fragments of an arbitrary SQL that are interpolated into the main query, e.g.
const uniquePairs = [
['a', 1],
['b', 2]
];
let placeholderIndex = 1;
const whereConditionSql = uniquePairs
.map(() => {
return needleColumns
.map((column) => {
return column + ' = $' + placeholderIndex++;
})
.join(' AND ');
})
.join(' OR ');
const values = [];
for (const pairValues of uniquePairs) {
values.push(...pairValues);
}
const query = sql`
SELECT
id
FROM foo
WHERE
${sql.raw(whereConditionSql, values)}
`;
await connection.any(query);In the above example, query is:
{
sql: 'SELECT id FROM foo WHERE (a = $1 AND b = $2) OR (a = $3 AND b = $4)',
values: [
'a',
1,
'b',
2
]
}Multiple sql.raw fragments can be used to create a query.
Slonik began as a collection of utilities designed for working with node-postgres. We continue to use node-postgres as it provides a robust foundation for interacting with PostgreSQL. However, what once was a collection of utilities has since grown into a framework that abstracts repeating code patterns, protects against unsafe connection handling and value interpolation, and provides rich debugging experience.
Slonik has been battle-tested with large data volumes and queries ranging from simple CRUD operations to data-warehousing needs.
Slonik will strip all comments and line-breaks from a query before processing it.
This makes logging of the queries easier.
The implication is that your query cannot contain values that include a newline character, e.g.
// Do not do this
connection.query(sql`INSERT INTO foo (bar) VALUES ('\n')`);If you want to communicate a value that includes a multiline character, use value placeholder interpolation, e.g.
connection.query(sql`INSERT INTO foo (bar) VALUES (${'\n'})`);Slonik query methods can only be executed using sql tagged template literal, e.g.
import {
sql
} from 'slonik'
connection.query(sql`
SELECT 1
FROM foo
WHERE bar = ${'baz'}
`);The above is equivalent to evaluating:
SELECT 1
FROM foo
WHERE bar = $1
query with 'baz' value binding.
(members: $ReadOnlyArray<PrimitiveValueExpressionType>) => SetSqlTokenType;sql.set is used to create a typed row construct (or a set, depending on the context), e.g.
await connection.query(sql`
SELECT ${sql.set([1, 2, 3])}
`);Produces:
{
sql: 'SELECT ($1, $2, $3)',
values: [
1,
2,
3
]
}(sets: $ReadOnlyArray<$ReadOnlyArray<PrimitiveValueExpressionType>>) => MultisetSqlTokenType;sql.multiset is used to create a comma-separated list of typed row constructs, e.g.
await connection.query(sql`
SELECT ${sql.multiset([
[1, 2, 3],
[4, 5, 6]
])}
`);Produces:
{
sql: 'SELECT ($1, $2, $3), ($4, $5, $6)',
values: [
1,
2,
3,
4,
5,
6
]
}(names: $ReadOnlyArray<string>) => IdentifierTokenType;Delimited identifiers are created by enclosing an arbitrary sequence of characters in double-quotes ("). To create create a delimited identifier, create an sql tag function placeholder value using sql.identifier, e.g.
sql`
SELECT 1
FROM ${sql.identifier(['bar', 'baz'])}
`;Produces:
{
sql: 'SELECT 1 FROM "bar"."bar"',
values: []
}(rawSql: string, values?: $ReadOnlyArray<PrimitiveValueExpressionType>) => RawSqlTokenType;Raw/ dynamic SQL can be inlined using sql.raw, e.g.
sql`
SELECT 1
FROM ${sql.raw('"bar"')}
`;Produces:
{
sql: 'SELECT 1 FROM "bar"',
values: []
}The second parameter of the sql.raw can be used to bind values, e.g.
sql`
SELECT ${sql.raw('$1', [1])}
`;Produces:
{
sql: 'SELECT $1',
values: [
1
]
}Returns result rows.
Example:
const rows = await connection.any(sql`SELECT foo`);#any is similar to #query except that it returns rows without fields information.
Returns value of the first column of every row in the result set.
- Throws
DataIntegrityErrorif query returns multiple rows.
Example:
const fooValues = await connection.anyFirst(sql`SELECT foo`);Used when inserting 1 row.
Example:
const {
insertId
} = await connection.insert(sql`INSERT INTO foo SET bar='baz'`);The reason for using this method over #query is to leverage the strict types. #insert method result type is InsertResultType.
Returns result rows.
- Throws
NotFoundErrorif query returns no rows.
Example:
const rows = await connection.many(sql`SELECT foo`);Returns value of the first column of every row in the result set.
- Throws
NotFoundErrorif query returns no rows. - Throws
DataIntegrityErrorif query returns multiple rows.
Example:
const fooValues = await connection.many(sql`SELECT foo`);Selects the first row from the result.
- Returns
nullif row is not found. - Throws
DataIntegrityErrorif query returns multiple rows.
Example:
const row = await connection.maybeOne(sql`SELECT foo`);
// row.foo is the result of the `foo` column value of the first row.Returns value of the first column from the first row.
- Returns
nullif row is not found. - Throws
DataIntegrityErrorif query returns multiple rows. - Throws
DataIntegrityErrorif query returns multiple columns.
Example:
const foo = await connection.maybeOneFirst(sql`SELECT foo`);
// foo is the result of the `foo` column value of the first row.Selects the first row from the result.
- Throws
NotFoundErrorif query returns no rows. - Throws
DataIntegrityErrorif query returns multiple rows.
Example:
const row = await connection.one(sql`SELECT foo`);
// row.foo is the result of the `foo` column value of the first row.Note:
I've been asked "What makes this different from knex.js
knex('foo').limit(1)?".knex('foo').limit(1)simply generates "SELECT * FROM foo LIMIT 1" query.knexis a query builder; it does not assert the value of the result. Slonik#oneadds assertions about the result of the query.
Returns value of the first column from the first row.
- Throws
NotFoundErrorif query returns no rows. - Throws
DataIntegrityErrorif query returns multiple rows. - Throws
DataIntegrityErrorif query returns multiple columns.
Example:
const foo = await connection.oneFirst(sql`SELECT foo`);
// foo is the result of the `foo` column value of the first row.API and the result shape are equivalent to pg#query.
transaction method is used wrap execution of queries in START TRANSACTION and COMMIT or ROLLBACK. COMMIT is called if the transaction handler returns a promise that resolves; ROLLBACK is called otherwise.
transaction method can be used together with createPool method. When used to create a transaction from an instance of a pool, a new connection is allocated for the duration of the transaction.
const result = await connection.transaction(async (transactionConnection) => {
await transactionConnection.query(sql`INSERT INTO foo (bar) VALUES ('baz')`);
await transactionConnection.query(sql`INSERT INTO qux (quux) VALUES ('quuz')`);
return 'FOO';
});
result === 'FOO';All Slonik errors extend from SlonikError, i.e. You can catch Slonik specific errors using the following logic.
import {
SlonikError
} from 'slonik';
try {
await query();
} catch (error) {
if (error instanceof SlonikError) {
// This error is thrown by Slonik.
}
}To handle the case where query returns less than one row, catch NotFoundError error.
import {
NotFoundError
} from 'slonik';
let row;
try {
row = await connection.one(sql`SELECT foo`);
} catch (error) {
if (!(error instanceof NotFoundError)) {
throw error;
}
}
if (row) {
// row.foo is the result of the `foo` column value of the first row.
}To handle the case where the data result does not match the expectations, catch DataIntegrityError error.
import {
NotFoundError
} from 'slonik';
let row;
try {
row = await connection.one(sql`SELECT foo`);
} catch (error) {
if (error instanceof DataIntegrityError) {
console.error('There is more than one row matching the select criteria.');
} else {
throw error;
}
}NotNullIntegrityConstraintViolationError is thrown when Postgres responds with unique_violation (23502) error.
ForeignKeyIntegrityConstraintViolationError is thrown when Postgres responds with unique_violation (23503) error.
UniqueIntegrityConstraintViolationError is thrown when Postgres responds with unique_violation (23505) error.
CheckIntegrityConstraintViolationError is thrown when Postgres responds with unique_violation (23514) error.
This package is using Flow types.
Refer to ./src/types.js.
The public interface exports the following types:
DatabaseConnectionTypeDatabasePoolConnectionTypeDatabaseSingleConnectionType
Use these types to annotate connection instance in your code base, e.g.
// @flow
import type {
DatabaseConnectionType
} from 'slonik';
export default async (
connection: DatabaseConnectionType,
code: string
): Promise<number> => {
const countryId = await connection.oneFirst(sql`
SELECT id
FROM country
WHERE code = ${code}
`);
return countryId;
};Slonik uses roarr to log queries.
To enable logging, define ROARR_LOG=true environment variable.
By default, Slonik logs the input query, query execution time and affected row count.
You can enable additional logging details by configuring the following environment variables.
# Logs query parameter values
export SLONIK_LOG_VALUES=true
SLONIK_LOG_STACK_TRACE=1 will create a stack trace before invoking the query and include the stack trace in the logs, e.g.
{"context":{"package":"slonik","namespace":"slonik","logLevel":20,"executionTime":"357 ms","queryId":"01CV2V5S4H57KCYFFBS0BJ8K7E","rowCount":1,"sql":"SELECT schedule_cinema_data_task();","stackTrace":["/Users/gajus/Documents/dev/applaudience/data-management-program/node_modules/slonik/dist:162:28","/Users/gajus/Documents/dev/applaudience/data-management-program/node_modules/slonik/dist:314:12","/Users/gajus/Documents/dev/applaudience/data-management-program/node_modules/slonik/dist:361:20","/Users/gajus/Documents/dev/applaudience/data-management-program/node_modules/slonik/dist/utilities:17:13","/Users/gajus/Documents/dev/applaudience/data-management-program/src/bin/commands/do-cinema-data-tasks.js:59:21","/Users/gajus/Documents/dev/applaudience/data-management-program/src/bin/commands/do-cinema-data-tasks.js:590:45","internal/process/next_tick.js:68:7"],"values":[]},"message":"query","sequence":4,"time":1540915127833,"version":"1.0.0"}
{"context":{"package":"slonik","namespace":"slonik","logLevel":20,"executionTime":"66 ms","queryId":"01CV2V5SGS0WHJX4GJN09Z3MTB","rowCount":1,"sql":"SELECT cinema_id \"cinemaId\", target_data \"targetData\" FROM cinema_data_task WHERE id = ?","stackTrace":["/Users/gajus/Documents/dev/applaudience/data-management-program/node_modules/slonik/dist:162:28","/Users/gajus/Documents/dev/applaudience/data-management-program/node_modules/slonik/dist:285:12","/Users/gajus/Documents/dev/applaudience/data-management-program/node_modules/slonik/dist/utilities:17:13","/Users/gajus/Documents/dev/applaudience/data-management-program/src/bin/commands/do-cinema-data-tasks.js:603:26","internal/process/next_tick.js:68:7"],"values":[17953947]},"message":"query","sequence":5,"time":1540915127902,"version":"1.0.0"}
Use @roarr/cli to pretty-print the output.
Using Atom IDE you can leverage the language-babel package in combination with the language-sql to enable highlighting of the SQL strings in the codebase.
To enable highlighting, you need to:
- Install
language-babelandlanguage-sqlpackages. - Configure
language-babel"JavaScript Tagged Template Literal Grammar Extensions" setting to uselanguage-sqlto highlight template literals withsqltag (configuration value:sql:source.sql). - Use
sqlhelper to construct the queries.
For more information, refer to the JavaScript Tagged Template Literal Grammar Extensions documentation of language-babel package.
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