LocalDataAdapter Object

The LocalDataAdapter Object provides access to the current service to fetch data from it. This object can be accessed from the server only through the global lda variable.

The code snippet below shows how the lda object can be used:

function afterProcessDeltaChange(delta, change, wasRefreshed) {
   lda.insert("History", { Date: new Date(), RowID: change['ID'], UserID: session['UserID'] } );
   lda.applyChanges();
}

Properties

deltas

Represents an array (both by index and name) of all active deltas. Any calls to insert/update/delete will place new entries in the deltas property; these can be send to the database by calling applyChanges or thrown away by calling discardChanges.

Functions

insert(table, data)

Inserts a new row in table "table", the data should be a javascript inline object with a key:value pair for each field.

update(table, oldvalues, newvalues)

Updates a row in the table "table". The "oldvalues" parameter can be the same as the "newvalues" parameter if the primary key hasn't changed. Both values have to be javascript objects with key:value pairs.

remove(table, data)

Removes a row in table "table". The data has to match the primary key of the row to delete and has to be a javascript object with key:value pairs for all fields in the primary key.

Example:

 lda.remove('CustomTable', {Id:CustomValue});
 lda.applyChanges();

discardChanges()

Drops all current changes and empties the deltas property.

applyChanges()

Sends the changes to the database, if successful, it will empty the deltas property, else, it will throw an exception.

selectSQL(sql, parameters)

Executes the DA SQL request with optional parameters. parameters should be a complex object with property names matching the request parameter names.

Returns a SelectResult Object.

Example:

var result1 = lda.selectSQL('SELECT * FROM customers');

var sql = 'SELECT * FROM customers WHERE id=:pCustomerId';
var params = { pCustomerId : '3217032B-47DB-400A-9A6E-012CBDF1E1E5' };
var result2 = lda.selectSQL(sql, params);

selectWhere(table, fields, where, parameters)

Requests data from the Schema Table. The following data request parameters are used:

• table - requested table name
• fields - array containing names of the requested table fields
• where - request conditions expressed via a WhereExpression object
• parameters - a complex object with property names matching the request parameter names

Returns a SelectResult Object.

Example:

var where = WhereBuilder.createBinary(WhereBuilder.createField('Id'), WhereBuilder.createParameter('Id', 'String', 50), 'Equal');

var users = lda.selectWhere('Customers', [ 'Id', 'Name' ], where, { Id: '{3217032b-47db-400a-9a6e-012cbdf1e1e5}' });

log(users.count);

execute(commandName, parameters)

Executes the Schema Command with provided name. The parameters object is used to provide command parameter values.

Returns an object with properties containing out schema command parameters. The integer Schema Command execution result is represented as result property of the result object.

Example:

var result = lda.execute('CustomSchemaCommand', { EntityId: '{3217032b-47db-400a-9a6e-012cbdf1e1e5}', EntityName: 'TestValue' } );

log(JSON.stringify(result));