I am currently working with SAPUI5 and developing a extension for the Web Client using the OData Model V4 for data retrieval. However, I am having trouble concerning data binding of a child collection. The datastructure I want to access (which partially works, except for the collection) looks as follows:

{
    "Code": "5",
    "OBJ_CUST_ADDRCollection": [
        {
            "Code": "5",
            "U_Address": "Construction site",
            "U_Street": "Sample Street 20",
            "U_City": "New York",
            "U_ZipCode": "1234",
            "U_CntctName": "John Doe"
        }
        //This array usually contains multiple entries which have the same schema as the one above.
    ]
}

My model’s configuration looks as follows:

export const bpModel: ODataModel = new ODataModel({
        serviceUrl: `/b1s/v2/`,
        synchronizationMode: "None",
        operationMode: "Server",
        autoExpandSelect: true,
        earlyRequests: true,
        groupProperties : {
            UpdateGroup : {"submit" : "API"}
        },
        updateGroupId : updateGroupId
    });

To retrieve a specific entity, I have used an element binding to bind the bpModel to my view (the key is ‘5’ in this instance):

view.bindElement({
  path: `/OBJECT_CUSTOMER('${routingParams.customerObjCode}')`,
  model: bpModelName
});

I am using a fragment (for better readability) in my view, which contains the data binding to the collection “OBJ_CUST_ADDRCollection”:

<core:FragmentDefinition 
    xmlns="sap.m"
    xmlns:mvc="sap.ui.core.mvc"
    xmlns:core="sap.ui.core">

        <VBox width="100%">
            <Title text="{i18n>objectAddresses}" class="sapUiSmallMarginBottom"/>
            <Table id="objAddresses" 
                mode="MultiSelect" 
                class="sapUiSmallMarginBottom"
                items="{
                    path: 'OBJ_CUST_ADDRCollection',
                    model: 'BP'
                }"
                sticky="HeaderToolbar,InfoToolbar,ColumnHeaders">
                <headerToolbar>
                    <OverflowToolbar>
                        <ToolbarSpacer/>
                        <Button icon="sap-icon://add" press="addAddress"/>
                        <Button icon="sap-icon://delete" press="deleteAddresses"/>
                        <Button icon="sap-icon://action-settings" press="changeObjAddressSettings"/>
                    </OverflowToolbar>
                </headerToolbar>
                <columns>
                    <Column>
                        <Text text="{i18n>objectAddressesID}"/>
                    </Column>
                    <Column>
                        <Text text="{i18n>objectAddressesStreetPOBox}"/>
                    </Column>
                    <Column>
                        <Text text="{i18n>objectAddressesLocation}"/>
                    </Column>
                    <Column>
                        <Text text="{i18n>objectAddressesZipCode}"/>
                    </Column>
                    <Column>
                        <Text text="{i18n>objectAddressesCntctAtLoc}"/>
                    </Column>
                </columns>
                <items>
                    <ColumnListItem>
                        <cells>
                            <Text text="{BP>U_Address}" />
                            <Text text="{BP>U_Street}" />
                            <Text text="{BP>U_City}" />
                            <Text text="{BP>U_ZipCode}" />
                            <Text text="{BP>U_CntctName}" />
                        </cells>
                    </ColumnListItem>
                </items>
            </Table>
        </VBox>
</core:FragmentDefinition>

But whenever this fragment (and the corresponding view) is loaded, I encounter the error “Failed to enhance query options for auto-$expand/$select as the child binding has query options, but its path ‘OBJ_CUST_ADDRCollection’ points to a structural property – {“$select”:[“U_Address”,”U_Street”,”U_City”,”U_ZipCode”,”U_CntctName”]} sap.ui.model.odata.v4.lib._Helper”. When checking and manually testing the actual GET request sent by the OData model, I can see that the query parameter $select is used, which caused the request to fail. When I omitted this parameter (in my tests with Insomnia) the request worked.

How do I resolve this error?

At this point I have tried multiple things:

• Setting “autoExpandSelect” to false. This caused the issue to disappear and the collection’s contents were displayed correctly. Yet, this isn’t a solution to me, as I intend to use a deep create later on and “autoExpandSelect: true” is required for this.
• Changing the items aggregation slightly, by adding a “parameters” object containing $select: [ ] and $$ownRequest: true. The only thing this changed for me was, that my batch-request contained another request for the collection itself. The issue concerning $select still persists though.
• Using a Service Layer Extension written in JavaScript. This option gave me a bit more freedom concerning the design of the endpoint, but I wasn’t able to access it with batch-requests. I had to set the groupId to $direct and autoExpandSelect to false for data to be displayed. This did work in the end, but also isn’t ideal. Firstly, the performance seems to be far worse when using a custom endpoint. Secondly, deep create still won’t work due to autoExpandSelect being set to false.