wiki:DeveloperGuidelines/EdenMobile/Database

Version 11 (modified by Dominic König, 5 years ago) ( diff )

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EdenMobile Database

$emdb Service

EdenMobile provides the $emdb service to access the database.

To use the service, it must be included in the controller dependencies:

EdenMobile.controller("MyController", [
    '$scope', '$stateParams', '$emdb',
    function($scope, $stateParams, $emdb) {
        // controller code goes here
    }
]);

$emdb automatically creates the database and tables when it is initialized for the first time.

API

Remember that all database transactions are asynchronous! Callback functions may therefore need to perform a $scope.$apply to trigger a digest cycle explicitly.

table

The table API provides fundamental methods to access data in database tables, examples:

// Instantiate the API with the table name
table = $emdb.table("mytable");

// Insert records into the table
table.insert({
    // The data to insert
    'name': 'Example',
    'number': 4
}, function(recordID) {
    // Callback function after successful insert
});

// Select records from the table - general pattern
var fields = ['id', 'name'],
    query = 'number > 3';
table.select(fields, query, function(result) {
    var rows = result.rows,
        record;
    for (var i=0, len=rows.length; i<len; i++) {
        record = rows.item(i);
        // do something with the record
    }
});

// Other variants of select:
// Extract all records, but only certain fields
table.select(fields, function(result) {
    // process the result
});

// Extract all fields, but only certain records
table.select(query, function(result) {
    // process the result
});

// Extract all fields from all records
table.select(function(result) {
    // process the result
});

Default Schema

The database schema is stored in the mobile database, in the em_schema table.

For the initial setup of the database, a static emDefaultSchema (in www/config/schema.js) is used. Once this schema has been written to the new database, it will be ignored.

The emDefaultSchema service also defines the meta-fields which are to be added to all user tables.

emSQL

$emDB uses the emSQL service to construct common SQL statements. It can be found in www/services/sql.js.

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