2.1.3 Data Model

It is highly recommended to mark the Use Data Model from the Properties sections and use the FAB Data Model Node in building up the fields, structures and tables list. The fields from the FAB Data Model Node will still have to be assigned to the Bound Field of the relevant control element. This will in turn create the same field list in the Fields Area Section like what has been exhibited in the above example.

FAB Data Model Node is similar to the Fields with the following additional characteristics:

1. Allows hierarchical/nested data model that provides a more logical definition.
   
   Root Node
   
   1. Customer - Individual field of type string
   2. Orders - Table for Order header
      1. OrdersStruct - Structure holding the Order header fields
      2. OrderItems - Table for Order items
         1. OrderItemsStruct - Structure holding the Order items fields
2. Fields can be referenced to SAP Data Elements
   
3. More fine-grained definition of model field properties (example field OrderDate is a Date in one part of the model, but String in another part).
   
   

Advantages of using the FAB Data Model Node

• Efficient runtime execution resulting to optimised performance
• Provides a variable CR_DATA in most FAB user-exits that allow much easier interrogation and setting of data in the app at run-time. Instead of working primarily with the [Field Name / Field Value] pairs, it works directly with ABAP nested structure to use exact field names and data types which promotes easier access and coding.
  
  
• FAB auto-generates a nested structure GS_DATA into the definition of the Implementation Class defined in the properties. This can be used for simpler use of the CR_DATA (Type ANY) by simply performing MOVE-CORRESPONDING CR_DATA TO GS_DATA in your implementations. If changing the data use MOVE-CORRESPONDING GS_DATA TO CR_DATA
  
• FAB User exits can directly modify the data upon an Action at run-time and reflect this in the front-end app immediately. Use the structure and technique mentioned in the previous point.
• Within JavaScript too it is easier to get/set data in the model. The data in the app at run-time has the same structure as represented in the FAB/ABAP Data Model Note only that it is in JSON format. Here we know of it more as the ‘Model’, and we can access it via standard JavaScript Code or more efficiently use the FAB delivered functions.
  

  For example: getField(“Orders”) will retrieve the array of Orders
  
  

  Here the first Order contains 2 OrderItems and the second as 3.
  
  

  You can access the OrderItems of the a particular index using the syntax getField("Orders/0/OrderItems")
  

  

How to use the FAB Data Model Node.

1. Mark the Use Data Model in the properties of the application
2. Right click on the Project and select Add Data Model
   
   
3. Right click on the Root Node and select either of the following:
   -Add Field - to add individual fields
   -Add Structure Type Node - to add structures
   -Add Table Type Node - to add table types
   -Adopt from Fields - choose this option to copy the Fields into the Data Model Root Node
   
4. Assign the Data Model field into the Bound Field of the control
   
   
5. Access the fields in Javascript using the FAB delivered functions and in FAB User Exits by referring to the variable CR_DATA

Note: If the Data Model is not selected in an app, and the option 'DoNotSave' is checked in the bound field of an input field, the data entered onto that particular field doesn't get saved in the backend table /IQX/FORMS_INST.