Fix Filter and Orderby in Expand applied on bound functions

[KenitoInc]

Issues

This pull request fixes #1162 .

Description

If we don't have an entity set path, the OperationSegment created doesn't have a TargetEdmNavigationSource. This cause the TargetNavigationSource in ODataPathInfo to be null.

For bound operation, this PR sets the TargetNavigationSource using the TargetEdmNavigationSource of the previous segment. e.g
Take the request Get ~/People/My.Function.GetPeopleWithDogs($filter=ID eq 1)
If GetPeopleWithDogs operation segment doesn't have a TargetEdmNavigationSource, we use the TargetEdmNavigationSource from the People entityset segment

Checklist (Uncheck if it is not completed)

• Test cases added
• Build and test with one-click build and test script passed

Additional work necessary

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[habbes]

Could previous.TargetEdmNavigationSource also be null, or that isn't an issue?

[habbes]

What if the return type of the of the operation does not match the navigation source of the previous segment?
For example, what if we have something like Customers/NS.GetTopOrders()?$expand=Products($filter=Category eq 'Electronics') where GetTopOrders returns a collection of Order entities from an Orders entity set, which is different from Customers entity set?

[xuzhg]

I don't think we should delegate the targetNS to the NS of preview segment.
we'd figure out why ODL needs the targetNS? If the last operation doesn't have the targetNS, can we use the return type of the operation to do something? I do think we use the TargetNS to calculate the context URL, if we don't have the NS, we should use the type to generate the Context URL. @mikepizzo

[paulodero]

FirstOrDefault() would return null if no element if found and therefore the Ln57 would through an error. If we are certain about getting an element, then FirstOrDefault() would be unnecessary, using First() would suffice. Better still we can use Single() to retrieve the element if we are always expecting a single element.

[xuzhg]

I don't think we should delegate the targetNS to the NS of preview segment.
we'd figure out why ODL needs the targetNS? If the last operation doesn't have the targetNS, can we use the return type of the operation to do something? I do think we use the TargetNS to calculate the context URL, if we don't have the NS, we should use the type to generate the Context URL. @mikepizzo

[gathogojr]

@KenitoInc Without even getting into whether this is the right fix, previous.TargetNavigationSource is null if previous is a KeySegment - e.g. for the case where the function is bound to an entity. On the other hand, (previous as KeySegment).NavigationSource is not null.

[gathogojr]

This is where you'd check if previous is null to avoid doing a lot of work for nothing...

[KenitoInc]

I think there was a clear reason why by design, applying query options ($filter applied on $expand) required an EntitySetPath.
The proposed fix in this PR was to assist in scenarios where the customer doesn't specify the EntitySetPath.
I have looked at various solutions and I am unable to come up with a fix because of the following reasons:
• The function only specifies a return type (IEdmType) not the return entity set
• It not possible to get the correct entityset from an edmtype since we could have multiple entitysets from one edmtype.

It’s from the EntitySet that we get the TargetNavigationSource to use in creating the BindingState during semantic binding by SelectExpandBinder, FilterBinder etc.