How to handle component link circular reference in DXA 2.0?

Question

I have Book schema, that has a component link to similar books. One of the similar books, has a component link back to original component. In such way I got circular reference.

When publishing this component with DXA 2.0 TBBs expandLinkDepth parameter handles it nicely, and as result I got only couple of levels included in JSON.

However my main issue is on webapp side, it is failing during model mapping.

Book model has next property:

[SemanticProperty("s:similar_books")]
public List<Book> SimilarBooks { get; set; }

Default DataModelBuilder successfully maps couple of levels of Books to my property, however the last level that was restricted by TBB expandLinkDepth is failing with such message:

Unable to map field 'SimilarBooks' to property Book.SimilarBooks of type ...

It fails on this line of BuildEntityModel method of DefaultModelBuilder, because SchemaId is null.

SemanticSchema semanticSchema = SemanticMapping.GetSchema(entityModelData.SchemaId, localization);

Probably we can enhance DXA to avoid exception, however:

How should we handle such circular reference situations in general with DXA Models?

Thanks!

Answer 1

Although this sounds like a defect in the DXA Framework in general, I think a work-around is possible, since you mentioned you don’t need more than one level expansion:

Create a new View Model Type, say SimilarBook, which maps to the same Schema/Properties as Book, but don’t let if have a SimilarBooks property.

Let the Books.SimilarBooks propery be of type List<SimilarBook>. This effectively breaks the recursive nature of the association.