Resolving the Unable to find field aEntity.externalId in BEntity Error in Hibernate Search

Описание: This guide addresses the common error in Hibernate Search related to indexed ManyToOne relationships and how to effectively resolve it.
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This video is based on the question https://stackoverflow.com/q/63789996/ asked by the user 'Aymen Kanzari' ( https://stackoverflow.com/u/4739210/ ) and on the answer https://stackoverflow.com/a/63790648/ provided by the user 'yrodiere' ( https://stackoverflow.com/u/6692043/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Resolving the Unable to find field aEntity.externalId in BEntity Error in Hibernate Search

When working with Hibernate Search and indexed entities, you might encounter an issue while trying to search into a ManyToOne relationship. Specifically, an error like "Unable to find field aEntity.externalId in BEntity" can pop up unexpectedly. This can be especially confusing if you're unfamiliar with how Hibernate handles indexing for related entities. In this post, we will break down the problem and provide clear solutions to resolve the error you are facing.

Understanding the Problem

The issue arises from your entity mapping when trying to leverage the @ IndexedEmbedded annotation to access the externalId field of the AEntity class from the BEntity class. Here’s a brief overview of your setup:

AEntity has a OneToMany relationship with BEntity and is indexed.

BEntity references AEntity through a ManyToOne relationship and is also indexed.

When you execute a search query that looks for aEntity.externalId, the Hibernate Search framework can't find it, throwing the error mentioned.

The Root of the Issue

The main reason behind this error is that the document ID field, which is externalId in your case, isn't included by @ IndexedEmbedded automatically. This can create confusion since you might expect it to work with minimal configuration.

Solutions to the Problem

Solution 1: Define a Separate Field

One of the best practices is to define a separate field for your entity ID instead of relying on the document ID. This gives you greater flexibility in indexing and querying. Here’s how you can do that:

Modify your AEntity class to include @ Field and @ DocumentId:

[[See Video to Reveal this Text or Code Snippet]]

Keep your BEntity unchanged unless necessary.

This change ensures that externalId is indexed and easily accessible in your search queries.

Solution 2: Use includeEmbeddedObjectId

If you prefer to use the document ID field directly, you can leverage the includeEmbeddedObjectId attribute to include it in your indexed data:

Modify your BEntity as follows:

[[See Video to Reveal this Text or Code Snippet]]

With this annotation, Hibernate will include the embedded object ID of AEntity when indexing the fields of BEntity, making it accessible for search queries.

Important Note: Reindex Your Data

After making any of the changes, do not forget to reindex your data. This step is crucial for the changes to take effect and your application to function correctly without errors upon searching.

Conclusion

Encountering the "Unable to find field aEntity.externalId in BEntity" error in Hibernate Search can be frustrating, but with a clear understanding of how to structure your entities and which annotations to use, you can resolve the issue efficiently. By defining a separate field for your ID or using includeEmbeddedObjectId, you can successfully navigate the intricacies of Hibernate Search and optimize your entity relationships.

Now, you can confidently work with your indexed ManyToOne relationships in Hibernate Search without running into this annoying error!