OpenEdge Development: Mobile Applications - Product ...

JSDO overview
A Mobile resource can also support non-built-in invoke operations which can be
implemented by any ABL routines defined for the resource on the AppServer except
routines that already implement built-in Mobile operations. Routines that implement
invoke operations can have any signature defined with supported ABL data types. A
JSDO created for a Mobile resource with invoke operations has corresponding
non-built-in invocation methods that map to these invoke operations. Calling an
invocation method on the JSDO calls the implementing ABL routine, passing the
required input parameters and returning its output parameters and any return value to
the Mobile App with no direct effect on JSDO local storage. The Mobile App can do
whatever it needs to do with the results of an invocation method, including merging
them with JSDO local storage, if appropriate.
For more information on coding the implementing ABL routines of Mobile operations on
the AppServer, see Chapter 3, “Creating Mobile Services.”)
How JSDO local storage works
JSDO local storage stores temp-table records as JavaScript record objects according
to the schema of the data model supported by the Mobile resource of the JSDO. If the
data model is for a single temp-table, local storage can contain only record objects for
the specified temp-table.
If the data model is for a ProDataSet, local storage can contain record objects for the
temp-tables defined for the ProDataSet. By default, record objects for a ProDataSet are
maintained in local storage according to any data-relations defined for the ProDataSet.
This means, for example, that when a JSDO method finds a record object of a parent
temp-table, if a method is then called to search through the record objects of a
temp-table that is a child of that parent, the search will find only record objects that are
related to the record object found in the parent; if new record objects are added to the
same child temp-table, they are added with key fields set implicitly in relation to the
parent record object. The JSDO also supports the run-time option (by setting the
useRelationships property) of toggling between honoring these data-relations and
ignoring them when accessing temp-table data in local storage
Table and field references
You can access the data in local storage using table references. A table reference is a
property on the JSDO that references a given JavaScript temp-table object as defined
by the schema of the data model. So, local storage contains one table reference
property for each temp-table referenced in local storage. The name of each property is
the same as the name of a corresponding temp-table defined in the schema selected
to define the Mobile resource in Developer Studio (see Chapter 3, “Creating Mobile
Services”), and it is specified with the same letter case as the temp-table name in the
selected schema.
JSDO methods that operate on local storage operate either on the entire data store, in
which case they are called on the JSDO itself, or on one table reference at a time, in
which case they are called directly on the corresponding table reference property. For
example, given a JSDO referenced by dsOrderEntry whose local storage references
several temp-tables of a ProDataSet, including ttCustomer, two JSDO methods might
be called as follows:
dsOrderEntry.fill( );
dsOrderEntry.ttCustomer.foreach( function ( record-object ) { ... } );
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