loopback-connector-mysql/README.md

## loopback-connector-mysql

`loopback-connector-mysql` is the MySQL connector module for [loopback-datasource-juggler](http://docs.strongloop.com/loopback-datasource-juggler/).

## Usage

To use it you need `loopback-datasource-juggler`.

1. Setup dependencies in `package.json`:

    ```json
    {
      ...
      "dependencies": {
        "loopback-datasource-juggler": "latest",
        "loopback-connector-mysql": "latest"
      },
      ...
    }
    ```

2. Use:

    ```javascript
        var DataSource = require('loopback-datasource-juggler').DataSource;
        var dataSource = new DataSource('mysql', {
            host: 'localhost',
            port: 3306,
            database: 'mydb',
            username: 'myuser',
            password: 'mypass'
        });
    ```
    You can optionally pass a few additional parameters supported by [`node-mysql`](https://github.com/felixge/node-mysql),
    most particularly `password` and `collation`. `Collation` currently defaults
    to `utf8_general_ci`. The `collation` value will also be used to derive the
    connection charset.


## Data type mappings

`loopback-connector-mysql` uses the following rules to map between JSON types and MySQL data types.

### JSON to MySQL types

- String/JSON: VARCHAR
- Text: TEXT
- Number: INT
- Date: DATETIME
- BOOLEAN: TINYINT(1)
- Point/GeoPoint: POINT
- Enum: ENUM

### MySQL to JSON types

- CHAR: String
- CHAR(1): Boolean
- VARCHAR/TINYTEXT/MEDIUMTEXT/LONGTEXT/TEXT/ENUM/SET: String
- TINYBLOB/MEDIUMBLOB/LONGBLOB/BLOB/BINARY/VARBINARY/BIT: Binary
- TINYINT/SMALLINT/INT/MEDIUMINT/YEAR/FLOAT/DOUBLE/NUMERIC/DECIMAL: Number
- DATE/TIMESTAMP/DATETIME: Date

## Using the `dataType` field/column option with MySQL

`loopback-connector-mysql` allows mapping of LoopBack model properties to MYSQL columns using the 'mysql' property of the
 property definition. For example,

    "locationId":{
        "type":"String",
        "required":true,
        "length":20,
        "mysql":
        {
            "columnName":"LOCATION_ID",
            "dataType":"VARCHAR2",
            "dataLength":20,
            "nullable":"N"
        }
    }

`loopback-connector-mysql` also supports using the `dataType` column/property attribute to specify what MySQL column
type is used 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:
      `{ count : { type: Number, dataType: 'smallInt' }}`

  - floating point types
    - float
    - double
     
     Use the `precision` and `scale` options to specify custom precision. Default is (16,8).

     Example:
      `{ average : { type: Number, dataType: 'float', precision: 20, scale: 4 }}`

  - fixed-point exact value types
    - decimal
    - numeric

     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:
      `{ stdDev : { type: Number, dataType: 'decimal', precision: 12, scale: 8 }}`

- String / DataSource.Text / DataSource.JSON
  - varchar
  - char
  - text
  - mediumtext
  - tinytext
  - longtext
  
  Example:
   `{ userName : { type: String, dataType: 'char', limit: 24 }}`

  Example:
   `{ biography : { type: String, dataType: 'longtext' }}`

- Date
  - datetime
  - timestamp
  
  Example:
   `{ 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 }}`


## Discovering Models

MySQL data sources allow you to discover model definition information from existing mysql databases. See the following APIs:

 - [dataSource.discoverModelDefinitions([owner], fn)](https://github.com/strongloop/loopback#datasourcediscovermodeldefinitionsusername-fn)
 - [dataSource.discoverSchema([owner], name, fn)](https://github.com/strongloop/loopback#datasourcediscoverschemaowner-name-fn)

### Asynchronous APIs for discovery

* MySQL.prototype.discoverModelDefinitions = function (options, cb)
  - options:
    - all: {Boolean} To include tables/views from all schemas/owners
    - owner/schema: {String} The schema/owner name
    - views: {Boolean} To include views
  - cb:
    - Get a list of table/view names, for example:

        {type: 'table', name: 'INVENTORY', owner: 'STRONGLOOP' }
        {type: 'table', name: 'LOCATION', owner: 'STRONGLOOP' }
        {type: 'view', name: 'INVENTORY_VIEW', owner: 'STRONGLOOP' }


* MySQL.prototype.discoverModelProperties = function (table, options, cb)
  - table: {String} The name of a table or view
  - options:
    - owner/schema: {String} The schema/owner name
  - cb:
    - Get a list of model property definitions, for example:

          { owner: 'STRONGLOOP',
            tableName: 'PRODUCT',
            columnName: 'ID',
            dataType: 'VARCHAR2',
            dataLength: 20,
            nullable: 'N',
            type: 'String' }
          { owner: 'STRONGLOOP',
            tableName: 'PRODUCT',
            columnName: 'NAME',
            dataType: 'VARCHAR2',
            dataLength: 64,
            nullable: 'Y',
            type: 'String' }


* MySQL.prototype.discoverPrimaryKeys= function(table, options, cb)
  - table: {String} The name of a table or view
  - options:
    - owner/schema: {String} The schema/owner name
  - cb:
    - Get a list of primary key definitions, for example:

        { owner: 'STRONGLOOP',
          tableName: 'INVENTORY',
          columnName: 'PRODUCT_ID',
          keySeq: 1,
          pkName: 'ID_PK' }
        { owner: 'STRONGLOOP',
          tableName: 'INVENTORY',
          columnName: 'LOCATION_ID',
          keySeq: 2,
          pkName: 'ID_PK' }

* MySQL.prototype.discoverForeignKeys= function(table, options, cb)
  - table: {String} The name of a table or view
  - options:
    - owner/schema: {String} The schema/owner name
  - cb:
    - Get a list of foreign key definitions, for example:

        { fkOwner: 'STRONGLOOP',
          fkName: 'PRODUCT_FK',
          fkTableName: 'INVENTORY',
          fkColumnName: 'PRODUCT_ID',
          keySeq: 1,
          pkOwner: 'STRONGLOOP',
          pkName: 'PRODUCT_PK',
          pkTableName: 'PRODUCT',
          pkColumnName: 'ID' }


* MySQL.prototype.discoverExportedForeignKeys= function(table, options, cb)

  - table: {String} The name of a table or view
  - options:
    - owner/schema: {String} The schema/owner name
  - cb:
    - Get a list of foreign key definitions that reference the primary key of the given table, for example:

        { fkName: 'PRODUCT_FK',
          fkOwner: 'STRONGLOOP',
          fkTableName: 'INVENTORY',
          fkColumnName: 'PRODUCT_ID',
          keySeq: 1,
          pkName: 'PRODUCT_PK',
          pkOwner: 'STRONGLOOP',
          pkTableName: 'PRODUCT',
          pkColumnName: 'ID' }


### Synchronous APIs for discovery

* MySQL.prototype.discoverModelDefinitionsSync = function (options)
* MySQL.prototype.discoverModelPropertiesSync = function (table, options)
* MySQL.prototype.discoverPrimaryKeysSync= function(table, options)
* MySQL.prototype.discoverForeignKeysSync= function(table, options)
* MySQL.prototype.discoverExportedForeignKeysSync= function(table, options)

### Discover/build/try the models

#### Build a LDL schema by discovery

Data sources backed by the MySQL connector can discover LDL models from the database using the `discoverSchema` API. For
example,

    dataSource.discoverSchema('INVENTORY', {owner: 'STRONGLOOP'}, function (err, schema) {
        ...
    }

Here is the sample result. Please note there are 'mysql' properties in addition to the regular LDL model options and
properties. The 'mysql' objects contain the MySQL specific mappings.

    {
      "name":"Inventory",
      "options":{
        "idInjection":false,
        "mysql":{
          "schema":"STRONGLOOP",
          "table":"INVENTORY"
        }
      },
      "properties":{
        "productId":{
          "type":"String",
          "required":false,
          "length":60,
          "precision":null,
          "scale":null,
          "id":1,
          "mysql":{
            "columnName":"PRODUCT_ID",
            "dataType":"varchar",
            "dataLength":60,
            "dataPrecision":null,
            "dataScale":null,
            "nullable":"NO"
          }
        },
        "locationId":{
          "type":"String",
          "required":false,
          "length":60,
          "precision":null,
          "scale":null,
          "id":2,
          "mysql":{
            "columnName":"LOCATION_ID",
            "dataType":"varchar",
            "dataLength":60,
            "dataPrecision":null,
            "dataScale":null,
            "nullable":"NO"
          }
        },
        "available":{
          "type":"Number",
          "required":false,
          "length":null,
          "precision":10,
          "scale":0,
          "mysql":{
            "columnName":"AVAILABLE",
            "dataType":"int",
            "dataLength":null,
            "dataPrecision":10,
            "dataScale":0,
            "nullable":"YES"
          }
        },
        "total":{
          "type":"Number",
          "required":false,
          "length":null,
          "precision":10,
          "scale":0,
          "mysql":{
            "columnName":"TOTAL",
            "dataType":"int",
            "dataLength":null,
            "dataPrecision":10,
            "dataScale":0,
            "nullable":"YES"
          }
        }
      }
    }

We can also discover and build model classes in one shot. The following example uses `discoverAndBuildModels` to discover,
build and try the models:

    dataSource.discoverAndBuildModels('INVENTORY', { owner: 'STRONGLOOP', visited: {}, associations: true},
         function (err, models) {
            // Show records from the models
            for(var m in models) {
                models[m].all(show);
            };

            // Find one record for inventory
            models.Inventory.findOne({}, function(err, inv) {
                console.log("\nInventory: ", inv);
                // Follow the foreign key to navigate to the product
                inv.product(function(err, prod) {
                    console.log("\nProduct: ", prod);
                    console.log("\n ------------- ");
                });
        });
    }

## License

[The MIT license](LICENSE).

The project was initially forked from [mysql-adapter](https://github.com/jugglingdb/mysql-adapter)
which carries the following copyright and permission notices:


    Copyright (C) 2012 by Anatoliy Chakkaev

    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.