Tip: Missing instructions for your LoopBack 3 use case? Please report a Migration docs issue on GitHub to let us know.
In LoopBack 3, models are the cornerstone. They describe shape of data (schema), provide persistence-related behavior and implement public (REST) API. Besides this core functionality, there are many ways how to extend the built-in behavior.
In LoopBack 4, many things changed but some remain the same. A model class is no longer responsible for everything. We have Models to describe shape of data, Repositories to provide persistence-related behavior and finally Controllers to implement public APIs. Under the hood, repositories are re-using a lot of the same persistence implementation you may know from LoopBack 3, therefore some concepts remain unchanged.
To make the migration guide easier to navigate, we split model-related instructions into several sub-sections.
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Migrating model definitions and built-in APIs describes how to migrate the core of your Models - the model definition, persistence behavior and public API provided by the framework itself.
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Migrating model relations explains how to migrate relations, from the definition of a relation to its public APIs.
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Migrating custom model methods show how to bring over custom methods that are enhancing models with new functionality, adding to the features provided by the framework.
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Migrating remoting hooks explains how to migrate hooks that are executed by the REST API layer.
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Migrating CRUD operation hooks’ shows how to migrate hooks (observers) that are executed by the persistence layer.
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Migrating model mixins provides instructions for migrating mixins - small components that can enhance Model schema, behavior, or both.