Generate valid id/read/edit links for expanded non-contained resource with a contained navigation source

[gathogojr]

This pull request fixes OData/odata.net#2273.

Description

In the described scenario, a Site entity type has a contained Plants navigation property. The Plant entity type in turn has a contained Pipelines navigation property. The Pipeline entity type in turn has a non-contained single-valued Plant navigation property.

The non-contained Plant navigation property is bound to the Plants contained entity set via the Edm path Sites/Plants:

namespace Core
{
    public abstract class EntityBase
    {
        [Key]
        public int Id { get; set; }
        public string Name { get; set; }
        public Dictionary<string, object>? Attributes { get; set; }
    }

    public class Site : EntityBase
    {
        [Contained]
        public IEnumerable<Plant>? Plants { get; set; }
    }

    public class Plant : EntityBase
    {
        public Site Site { get; set; }
        [Contained]
        public IEnumerable<PipelineBase> Pipelines { get; set; }
    }

    public abstract class PipelineBase : EntityBase
    {
        public Plant Plant { get; set; }
    }
}

namespace Plant1
{
    public class Pipeline : PipelineBase
    {
        public int? Length { get; set; }
    }
}

The Sites entity set and the navigation property bindings are as follows:

<EntitySet Name=""Sites"" EntityType=""Core.Site"">
    <NavigationPropertyBinding Path=""Plants/Pipelines/Plant"" Target=""Sites/Plants""/>
    <NavigationPropertyBinding Path=""Plants/Site"" Target=""Sites""/>
</EntitySet>

If the $format or Accept request headers specify odata.metadata=full, and we attempt to expand the Plant navigation property, i.e., /Sites(1)/Plants(1)/Pipelines(1)?$expand=Plant - where Plant is non-contained, failure to use the link builder to build the id/read/edit links results into invalid links since we generate the links by appending /Plants(1) to the parent Pipeline resource id - /Sites(1)/Plants(1)/Pipelines(1) => /Sites(1)/Plants(1)/Pipelines(1)/Plants(1). This link is invalid since there's no Plants navigation property on Pipeline entity type.

The following line causes us not to use the link builder to generate the id/read/edit links if the resourceContext.NavigationSource is a contained entity set:

AspNetCoreOData/src/Microsoft.AspNetCore.OData/Formatter/Serialization/ODataResourceSerializer.cs

Line 584 in d94daad

if (!(resourceContext.NavigationSource is IEdmContainedEntitySet))

This PR fixes the issue by causing the link builder to be used if resourceContext.NavigationSource is a contained entity set and an expanded non-contained resource is being written. A navigation property binding should exist and a navigation link builder should be on hand to build the links.

Tests verify that expected behaviour is observed even when the non-contained navigation property is in a nested expand.

Checklist (Uncheck if it is not completed)

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

[ElizabethOkerio]

This name doesn't really give an overview of what these tests are for.. Use a more descriptive name for this scenario for all the files.

[gathogojr]

@ElizabethOkerio What would you propose?

[ElizabethOkerio]

LinksForExpandedResourcesWithContainedNavSources .. this is too long but something in those lines.

[gathogojr]

@ElizabethOkerio None of the existing directories that categorize tests under it has this level of detail - LinksForExpandedResourcesWithContainedNavSources. The directory name is a just pointer to the kind of tests one should expect under it. I renamed the directory to MetadataProperties which in essence is what the fix is all about. The tests are a combination of many scenarios (contained properties, non-contained properties, expanded navigation properties, nested expansion, etc.) - and tests for more scenario could be added with time. The key thing we're testing is that the generated metadata properties (@odata.id, @odata.editLink, @odata.associationLink, @odata.navigationLink, etc.) are valid.

[habbes]

Here there's no type segment?

[gathogojr]

@habbes There shouldn't be a type segment there. The Site navigation property is not initialized to a derived type as is the case for the Pipelines navigation property.