3.7 KiB

Raw Blame History

jugglingdb-schema(3) - Everything about schema, data types and model definition.

DESCRIPTION

Schema is a factory for classes. Schema connected with specific database using adapter.

All classes within single schema shares same adapter type and one database connection. But it's possible to use more than one schema to connect with different databases.

EVENTS

Instances of Schema are event emitters, events supported by default:

.on('connected', function() {}): Fired when db connection established. Params: none.
.on('log', function(msg, duration) {}): Fired when adapter logged line. Params: String message, Number duration

USAGE

Creating schema

Schema constructor available on jugglingdb module:

var Schema = require('jugglingdb').Schema;

Schema constructor accepts two arguments. First argument is adapter. It could be adapter name or adapter package:

var schemaByAdapterName = new Schema('memory');
var schemaByAdapterPackage = new Schema(require('redis'));

Settings

Second argument is optional settings. Settings object format and defaults depends on specific adapter, but common fields are:

host: Database host
port: Database port
username: Username to connect to database
password: Password to connect to database
database: Database name
debug: Turn on verbose mode to debug db queries and lifecycle

For adapter-specific settings refer to adapter's readme file.

Connecting to database

Schema connecting to database automatically. Once connection established schema object emit 'connected' event, and set connected flag to true, but it is not necessary to wait for 'connected' event because all queries cached and executed when schema emit 'connected' event.

To disconnect from database server call schema.disconnect method. This call forwarded to adapter if adapter have ability to connect/disconnect.

Model definition

To define model schema have single method schema.define. It accepts three argumets:

model name: String name in camel-case with first upper-case letter. This name will be used later to access model.
properties: Object with property type definitions. Key is property name, value is type definition. Type definition can be function representing type of property (String, Number, Date, Boolean), or object with {type: String|Number|..., index: true|false} format.
settings: Object with model-wide settings such as tableName or so.

Examples of model definition:

var User = schema.define('User', {
    email: String,
    password: String,
    birthDate: Date,
    activated: Boolean
});

var User = schema.define('User', {
    email: { type: String, limit: 150, index: true },
    password: { type: String, limit: 50 },
    birthDate: Date,
    registrationDate: {
        type: Date,
        default: function () { return new Date }
    },
    activated: { type: Boolean, default: false }
}, {
    tableName: 'users'
});

DB structure syncronization

Schema instance have two methods for updating db structure: automigrate and autoupdate.

The automigrate method drop table (if exists) and create it again, autoupdate method generates ALTER TABLE query. Both method accepts callback called when migration/update done.

To check if any db changes required use isActual method. It accepts single callback argument, which receive boolean value depending on db state: false if db structure outdated, true when schema and db is in sync:

schema.isActual(function(err, actual) {
    if (!actual) {
        schema.autoupdate();
    }
});

3.7 KiB Raw Blame History