Monthly Archives: September 2022

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Spring Data MongoDB MappingInstantiationException

Polymorphic fields with MongoDB and Spring Data

Depending on your needs using polymorphism might benefit different aspects of the project. For example, having a limited class hierarchy might make your code cleaner and more expressive in contrast to a single class having nullable fields or a type label. And it only seems natural to use it with document-oriented databases like MongoDB. But if you want to have a document with polymorphic fields using MongoDB and Spring Data you might face an exception similar to this: MappingInstantiationException: Failed to instantiate ...FieldType using constructor NO_CONSTRUCTOR with arguments. Let’s see why this happens and how to fix that issue properly.

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