loopback-connector-mysql/README.md

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# loopback-connector-mysql
[MySQL](https://www.mysql.com/) is a popular open-source relational database management system (RDBMS). The `loopback-connector-mysql` module provides the MySQL connector module for the LoopBack framework.
<div class="gh-only">See also <a href="http://loopback.io/doc/en/lb3/MySQL-connector.html">LoopBack MySQL Connector</a> in LoopBack documentation.
<br/><br/>
<b>NOTE</b>: The MySQL connector requires MySQL 5.0+.
</div>
## Installation
In your application root directory, enter this command to install the connector:
```sh
npm install loopback-connector-mysql --save
```
This installs the module from npm and adds it as a dependency to the application's `package.json` file.
If you create a MySQL data source using the data source generator as described below, you don't have to do this, since the generator will run `npm install` for you.
## Creating a MySQL data source
Use the [Data source generator](http://loopback.io/doc/en/lb3/Data-source-generator.html) to add a MySQL data source to your application.
The generator will prompt for the database server hostname, port, and other settings
required to connect to a MySQL database. It will also run the `npm install` command above for you.
The entry in the application's `/server/datasources.json` will look like this:
{% include code-caption.html content="/server/datasources.json" %}
```javascript
"mydb": {
"name": "mydb",
"connector": "mysql",
"host": "myserver",
"port": 3306,
"database": "mydb",
"password": "mypassword",
"user": "admin"
}
```
Edit `datasources.json` to add any other additional properties that you require.
### Properties
<table>
<thead>
<tr>
<th width="150">Property</th>
<th width="80">Type</th>
<th>Description</th>
</tr>
</thead>
<tbody>
<tr>
<td>collation</td>
<td>String</td>
<td>Determines the charset for the connection. Default is utf8_general_ci.</td>
</tr>
<tr>
<td>connector</td>
<td>String</td>
<td>Connector name, either “loopback-connector-mysql” or “mysql”.</td>
</tr>
<tr>
<td>connectionLimit</td>
<td>Number</td>
<td>The maximum number of connections to create at once. Default is 10.</td>
</tr>
<tr>
<td>database</td>
<td>String</td>
<td>Database name</td>
</tr>
<tr>
<td>debug</td>
<td>Boolean</td>
<td>If true, turn on verbose mode to debug database queries and lifecycle.</td>
</tr>
<tr>
<td>host</td>
<td>String</td>
<td>Database host name</td>
</tr>
<tr>
<td>password</td>
<td>String</td>
<td>Password to connect to database</td>
</tr>
<tr>
<td>port</td>
<td>Number</td>
<td>Database TCP port</td>
</tr>
<tr>
<td>socketPath</td>
<td>String</td>
<td>The path to a unix domain socket to connect to. When used host and port are ignored.</td>
</tr>
<tr>
<td>supportBigNumbers</td>
<td>Boolean</td>
<td>Enable this option to deal with big numbers (BIGINT and DECIMAL columns) in the database. Default is false.</td>
</tr>
<tr>
<td>timeZone</td>
<td>String</td>
<td>The timezone used to store local dates. Default is local.</td>
</tr>
<tr>
<td>url</td>
<td>String</td>
<td>Connection URL of form <code>mysql://user:password@host/db</code>. Overrides other connection settings.</td>
</tr>
<tr>
<td>username</td>
<td>String</td>
<td>Username to connect to database</td>
</tr>
</tbody>
</table>
**NOTE**: In addition to these properties, you can use additional parameters supported by [`node-mysql`](https://github.com/felixge/node-mysql).
## Type mappings
See [LoopBack types](http://loopback.io/doc/en/lb3/LoopBack-types.html) for details on LoopBack's data types.
### LoopBack to MySQL types
<table>
<thead>
<tr>
<th>LoopBack Type</th>
<th>MySQL Type</th>
</tr>
</thead>
<tbody>
<tr>
<td>String/JSON</td>
<td>VARCHAR</td>
</tr>
<tr>
<td>Text</td>
<td>TEXT</td>
</tr>
<tr>
<td>Number</td>
<td>INT</td>
</tr>
<tr>
<td>Date</td>
<td>DATETIME</td>
</tr>
<tr>
<td>Boolean</td>
<td>TINYINT(1)</td>
</tr>
<tr>
<td><a href="http://apidocs.strongloop.com/loopback-datasource-juggler/#geopoint" class="external-link">GeoPoint</a> object</td>
<td>POINT</td>
</tr>
<tr>
<td>Custom Enum type<br>(See <a href="#enum">Enum</a> below)</td>
<td>ENUM</td>
</tr>
</tbody>
</table>
### MySQL to LoopBack types
<table>
<tbody>
<tr>
<th>MySQL Type</th>
<th>LoopBack Type</th>
</tr>
<tr>
<td>CHAR</td>
<td>String</td>
</tr>
<tr>
<td>CHAR(1)</td>
<td>Boolean</td>
</tr>
<tr>
<td>VARCHAR<br>TINYTEXT<br>MEDIUMTEXT<br>LONGTEXT<br>TEXT<br>ENUM<br>SET</td>
<td>String</td>
</tr>
<tr>
<td>TINYBLOB<br>MEDIUMBLOB<br>LONGBLOB<br>BLOB<br>BINARY<br>VARBINARY<br>BIT</td>
<td>Node.js <a href="http://nodejs.org/api/buffer.html">Buffer object</a></td>
</tr>
<tr>
<td>TINYINT<br>SMALLINT<br>INT<br>MEDIUMINT<br>YEAR<br>FLOAT<br>DOUBLE<br>NUMERIC<br>DECIMAL</td>
<td>
<p>Number<br>For FLOAT and DOUBLE, see <a href="#floating-point-types">Floating-point types</a>. </p>
<p>For NUMERIC and DECIMAL, see <a href="MySQL-connector.html">Fixed-point exact value types</a></p>
</td>
</tr>
<tr>
<td>DATE<br>TIMESTAMP<br>DATETIME</td>
<td>Date</td>
</tr>
</tbody>
</table>
## Using the datatype field/column option with MySQL
Use the `mysql` model property to specify additional MySQL-specific properties for a LoopBack model.
For example:
{% include code-caption.html content="/common/models/model.json" %}
```javascript
"locationId":{
"type":"String",
"required":true,
"length":20,
"mysql":
{
"columnName":"LOCATION_ID",
"dataType":"VARCHAR2",
"dataLength":20,
"nullable":"N"
}
}
```
You can also use the dataType column/property attribute to specify what MySQL column type to use for many loopback-datasource-juggler types. 
The following type-dataType combinations are supported:
* Number
* integer
* tinyint
* smallint
* mediumint
* int
* bigint
Use the `limit` option to alter the display width. Example:
```javascript
{ userName : {
type: String,
dataType: 'char',
limit: 24
}
}
```
### Floating-point types
For Float and Double data types, use the `precision` and `scale` options to specify custom precision. Default is (16,8). For example:
```javascript
{ average :
{ type: Number,
dataType: 'float',
precision: 20,
scale: 4
}
}
```
### Fixed-point exact value types
For Decimal and Numeric types, use the `precision` and `scale` options to specify custom precision. Default is (9,2).
These aren't likely to function as true fixed-point.
Example:
```javascript
{ stdDev :
{ type: Number,
dataType: 'decimal',
precision: 12,
scale: 8
}
}
```
### Other types
Convert String / DataSource.Text / DataSource.JSON to the following MySQL types:
* varchar
* char
* text
* mediumtext
* tinytext
* longtext
Example: 
```javascript
{ userName :
{ type: String,
dataType: 'char',
limit: 24
}
}
```
Example: 
```javascript
{ biography :
{ type: String,
dataType: 'longtext'
}
}
```
Convert JSON Date types to  datetime or timestamp
Example: 
```javascript
{ startTime :
{ type: Date,
dataType: 'timestamp'
}
}
```
### Enum
Enums are special. Create an Enum using Enum factory:
```javascript
var MOOD = dataSource.EnumFactory('glad', 'sad', 'mad'); 
MOOD.SAD; // 'sad' 
MOOD(2); // 'sad' 
MOOD('SAD'); // 'sad' 
MOOD('sad'); // 'sad'
{ mood: { type: MOOD }}
{ choice: { type: dataSource.EnumFactory('yes', 'no', 'maybe'), null: false }}
```
## Discovery and auto-migration
### Model discovery
The MySQL connector supports _model discovery_ that enables you to create LoopBack models
based on an existing database schema using the unified [database discovery API](http://apidocs.strongloop.com/loopback-datasource-juggler/#datasource-prototype-discoverandbuildmodels). For more information on discovery, see [Discovering models from relational databases](https://loopback.io/doc/en/lb3/Discovering-models-from-relational-databases.html).
### Auto-migratiion
The MySQL connector also supports _auto-migration_ that enables you to create a database schema
from LoopBack models using the [LoopBack automigrate method](http://apidocs.strongloop.com/loopback-datasource-juggler/#datasource-prototype-automigrate).
For more information on auto-migration, see [Creating a database schema from models](https://loopback.io/doc/en/lb3/Creating-a-database-schema-from-models.html) for more information.
Destroying models may result in errors due to foreign key integrity. First delete any related models first calling delete on models with relationships.
## Running tests
The tests in this repository are mainly integration tests, meaning you will need to run them using our preconfigured test server.
1. Ask a core developer for instructions on how to set up test server credentials on your machine
2. `npm test`