OpenEdge Development: Mobile Applications - Product ...

Chapter 4: Creating Mobile Apps using JSDOs
Methods of a JSDO and the JSRecord object
Every JSDO has a number of methods, many of which interact with JSDO local
storage. Some are called on the JSDO itself, while most are called on a JSDO table
reference. Most execute synchronously, but some execute asynchronously as noted.
For more information, see the “Asynchronous and synchronous execution” section on
page 98. A few JSDO methods are also available on a JSRecord object.
A JSDO includes methods for:
• Executing built-in Mobile operations and calling their implementing AppServer
routines:
– fill( ) — Executes the read operation of a Mobile resource, loading the
temp-table records sent from the AppServer into JSDO local storage
according to the resource data model; the first record of every loaded
temp-table reference is set as its working record.
– saveChanges( ) — Executes the create, update, or delete operation of a
Mobile resource for each record that has changed in JSDO local storage
since the last execution of the fill( ) or saveChanges( ) method; no
working records for any table references in local storage are set.
These methods are always called on the JSDO and execute asynchronously.
• Executing non-built-in Mobile invoke operations and calling their implementing
AppServer routines. There is a uniquely named JSDO method defined for each
invoke operation in the Mobile resource; these methods have no effect on JSDO
local storage.
These methods are always called on the JSDO and, by default, execute
asynchronously, but can optionally execute synchronously. To pass input
parameters to the implementing ABL routine, you pass an input object to the
invocation method that contains properties with the values for any ABL input
parameters. A property for an ABL input parameter has the same name (and letter
case) as the corresponding input parameter, and has a JavaScript data type that
maps to the ABL data type of the input parameter (see Appendix A, “ABL to
JavaScript Data Type Mapping”)
• Updating JSDO local storage:
– add( ) — Called on a JSDO table reference, this method creates a new
record object for the temp-table in JSDO local storage; the new record is set
as the working record for the table reference.
– addRecords( ) — Called either on a JSDO or on a JSDO table reference,
this method updates JSDO local storage with record objects obtained from
an object passed as a parameter to the method that follows the same
schema as JSDO local storage; has no effect on existing working record
settings.
96 OpenEdge ® Development: Mobile Applications