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Accessing_Data_in_Controller_Code_17b30ac.md

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view on: demo kit nightly build | demo kit latest release

Accessing Data in Controller Code

In the OData V4 model, bindings are used to access and modify back-end data also if the data is accessed or modified in controller code.

You can create bindings that are independent of controls using the factory methods sap.ui.model.odata.v4.ODataModel#bindContext , sap.ui.model.odata.v4.ODataModel#bindList , and sap.ui.model.odata.v4.ODataModel#bindProperty .

Contexts

sap.ui.model.odata.v4.Context is central for CRUD operations in the controller code. sap.ui.model.odata.v4.Context provides the following functions:

  • requestObject: Returns a promise on the value for the given path relative to the context.

  • requestProperty: Returns a promise on the property value(s) for the given path(s) relative to the context. The value(s) will be requested from the back end if necessary.

  • getObject: Returns the value for the given path relative to this context

  • getProperty: Returns the property value for the given path relative to this context.

  • setProperty: Sets a new value for the property identified by the given path.

  • delete: Deletes the record.

Lists

A list binding is obtained either with sap.ui.model.odata.v4.ODataModel#bindList, or by getting an existing list binding bound to a control. Entities of the list can be requested using sap.ui.model.odata.v4.ODataModel.ODataListBinding#requestContexts. The function returns a promise resolving with an array of the requested contexts. The data of each context can be accessed using the requestObject, requestProperty, getObject, and getProperty methods of sap.ui.model.odata.v4.Context. To modify the data, sap.ui.model.odata.v4.Context#setProperty can be used. For retrieving all available contexts without sending any request, sap.ui.model.odata.v4.ODataListBinding#getAllCurrentContexts can be used.

var oList = oModel.bindList("/SalesOrderList");

oList.requestContexts(10, 20).then(function (aContexts) {
    aContexts.forEach(function (oContext) {
        // As we have fetched the data already, we can access "Note" through getProperty
        var sNote = oContext.getProperty("Note"); 
        if (!sNote) {
            oContext.setProperty("Note", "No notes");
        }
    });
});

New entities can be created with sap.ui.model.odata.v4.ODataModel.ODataListBinding#create . It is not required to read existing records before.

var oList = oModel.bindList("/SalesOrderList"),
    oNewContext = oList.create();

Relative Access

To access a list relative to an existing sap.ui.model.odata.v4.Context, use #getObject if that list is already loaded on the client by that context's binding. For example, when all items have been expanded in a list binding of sales orders,oSalesOrderContext.getObject("SO_2_SOITEM") would return them. Note that #requestObject cannot be used to fetch additional entities. To access a list that is not already loaded on the client, you need to create a new relative list binding as follows. You can also $expand further navigation properties; see sap.ui.model.odata.v4.ODataModel#bindList .

 // assuming oContext already exists
const oListBinding = oContext.getModel().bindList("SO_2_SOITEM", oContext, [
        new Sorter("ItemPosition")
    ], [
        new Filter("Quantity", FilterOperator.GT, "0")
    ], {
        $expand : {SOITEM_2_SCHDL : {$select : ["Quantity"]}},
        $select : ["ItemPosition"]
    });
const aContexts = await oListBinding.requestContexts();
// now access aContexts[0].getObject().ItemPosition etc.

Single Entities

A context binding is obtained either with sap.ui.model.odata.v4.ODataModel#bindContext, or by getting an existing context binding from the control tree. Data can be accessed through the bound context, see sap.ui.model.odata.v4.ODataContextBinding#getBoundContext . Using sap.ui.model.odata.v4.ODataContextBinding#requestObject is a shortcut for oBinding.getBoundContext().requestObject(). sap.ui.model.odata.v4.Context#setProperty is used to modify data.

Note:

Relative bindings need to be resolved, meaning that a context must have been set before data access is possible.

var oContextBinding = oModel.bindContext("/SalesOrderList('0500000000')");

oContextBinding.requestObject("Note").then(function (sNote) {
    if (!sNote) {
        oContextBinding.getBoundContext().setProperty("Note", "No notes");
    }
});

Relative Access

To access a single entity relative to an existing sap.ui.model.odata.v4.Context, use #getObject if that entity is already loaded on the client by that context's binding. Note that #requestObject cannot be used to fetch additional entities. To access a single entity that is not already loaded on the client, you need to create a new relative context binding as follows. You can also $expand further navigation properties; see sap.ui.model.odata.v4.ODataModel#bindContext .

// assuming oContext already exists
const oContextBinding = oContext.getModel().bindContext("toOther", oContext, {
    $expand : {"toYetAnother" : {$select : ["A", "B", "C"]},
    $select : ["AProperty", "AnotherProperty", "YetAnotherProperty"]
});
const oOtherEntity = await oContextBinding.getBoundContext().requestObject();
// now access oOtherEntity.AProperty, oOtherEntity.toYetAnother.A etc.

Single Properties

The access to single properties may either be done using a context binding as described above in the Single Entities section, or by using a property binding. The property binding is obtained with sap.ui.model.odata.v4.ODataModel#bindProperty , or by getting an existing property binding bound to a control. The value can be requested using sap.ui.model.odata.v4.ODataPropertyBinding#requestValue. A synchronous access is possible with sap.ui.model.odata.v4.ODataPropertyBinding#getValue, if the value is already available.

The value of a property binding can be modified using sap.ui.model.odata.v4.ODataPropertyBinding#setValue.

var oNote = oModel.bindProperty("/SalesOrderList('0500000000')/Note");
 
 
oNote.requestValue().then(function (sValue) {
    // do something with sValue
    // Note: We cannot use setValue as oNote is an absolute property binding
});

Relative Access

To access single properties relative to an existing sap.ui.model.odata.v4.Context, use #getProperty for access to already loaded properties, or #requestProperty in order to fetch additional properties not yet loaded on the client. You can also use #getObject to access the complete data the context points to or any part thereof, but #requestObject cannot be used to fetch additional properties. The value of a property can be modified using #setProperty.