OpenEdge Development: Mobile Applications - Product ...

Chapter 4: Creating Mobile Apps using JSDOs
For a non-built-in invoke operation that completes successfully, the response property
references an object that contains properties with the values of any output parameters
and return value returned by the ABL routine. A property for an ABL output parameter
has the same name (and letter case) as the corresponding output parameter, and has
a JavaScript data type that maps to the ABL data type of the output parameter (see
Appendix A, “ABL to JavaScript Data Type Mapping”). Any return value from the
routine is returned as the OpenEdge-defined property, _retVal, also with a
ABL-mapped JavaScript data type.
For a Mobile operation that completes with one or more ABL errors, the response
property references an object that contains two OpenEdge-defined properties:
• _retVal — A String with the value of any ABL RETURN ERROR string or
ReturnValue property for a thrown AppError object
• _errors — An array of JavaScript objects, each of which contains properties with
the ABL error message string and error number for one of possibly many
ABL-returned errors.
Note: In the current OpenEdge release, this array always returns one object only
for the first ABL error (the equivalent of ERROR-STATUS:GET-MESSAGE(1) in
ABL).
For more information on the request object and its available properties, see its
reference entry in Appendix B, “OpenEdge JavaScript Class and Object Reference”.
General error handling for Mobile operations
For any Mobile operation that completes with an error of any kind (ABL, Mobile Web
application, or network), the success property of the returned request object (and the
success parameter of the event handler) is set to false. As noted in the previous
section, any ABL errors can be found in the object returned by the response property.
All other Web application and network errors can be inspected using the xhr property
of the request object. For more information on the XMLHttpRequest object that this
property references, see the software development documentation for your Web
browser or mobile device.
Note that for a Mobile create, update, or delete operation, if any error, at any point
causes the operation to complete unsuccessfully, the record in JSDO local storage is
reverted prior to any change that caused the operation to be executed. So, for example,
a failed create operation causes the added record to be removed from local storage.
The record object that was originally added for the operation is then available for your
re-use as the jsrecord property of the request object (or the record parameter if the
event handler). A similar reversion occurs for the update and delete operations, with
the field values of any updated record reverted to their original values, and any deleted
record added back to local storage.
Properties of a JSDO
Every JSDO has several properties to manage its state. We have already introduced
the table reference properties that provide access to temp-table data loaded into JSDO
local storage, and the record property, which provides access to individual record
objects on a given table reference (see the “How JSDO local storage works” section on
page 93).
102 OpenEdge ® Development: Mobile Applications