Displayfieldname from MXDs rest query should include in the Return Fields

[AlirezaAhmadi]

Question: Why ESRI does not include Displayfieldname that is set in layer's MXD in the result of the list of Return Fields?
In my application if I do not include the Displayfieldname in the Return Fields of my Rest Query, my datagrid that is bound based on Displayfieldname fails.

[JenniferNery]

That is correct, QueryTask results only include fields that are specified in the Query.OutFields.

Are you using DataGrid or FeatureDataGrid? How does your binding statement look like? You can probably set a FallBackValue so that this does not fail.

{Binding Attributes[STATE_NAME], FallbackValue=NotAvailable}