Many-to-many relationships in EF Core 2.0 – Part 4: A more general abstraction

In the last few posts we saw how to hide use of the join entity from two entities with a many-to-many relationship. This post doesn’t add any additional functionality, it just abstracts some of what we saw so it can be re-used more easily.

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Many-to-many relationships in EF Core 2.0 – Part 3: Hiding as ICollection

In the previous post we ended up with entities that hide the join entity from the public surface. However, it was not possible to add or removed entities through this public surface. To enable this we need an ICollection implementation that acts as a true facade over the real join entity collection and delegates all responsibilities to that collection.

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Many-to-many relationships in EF Core 2.0 – Part 2: Hiding as IEnumerable

In the previous post we looked at how many-to-many relationships can be mapped using a join entity. In this post we’ll make the navigation properties to the join entity private so that they don’t appear in the public surface of our entity types. We’ll then add public IEnumerable properties that expose the relationship for reading without reference to the join entity.

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Many-to-many relationships in EF Core 2.0 – Part 1: The basics

As of EF Core 2.0, many-to-many relationships without an explicitly mapped join table are not supported. However, all is not lost. In this series of posts I will show:

  • Mapping many-to-many relationships with a join entity/table
  • Abstracting/hiding the join entity
    • In a simple way for read-only access to the relationship
    • In a more involved way that allows entities to be added and removed from each end

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EF 6.1: Creating indexes with IndexAttribute

Since EF 4.3 it has been possible to use CreateIndex and DropIndex in Code First Migrations to create and drop indexes. However this had to be done manually by editing the migration because the index was not included anywhere in the Code First model. Now with EF 6.1 it is possible to add index specifications to the model such that creating and dropping indexes can be handled automatically by Migrations. Continue reading

Database initializer and Migrations Seed methods

Entity Framework contains two different methods both called Seed that do similar things but behave slightly differently. The first was introduced in EF 4.1 and works with database initializers. The second was introduced in EF 4.3 as part of Code First Migrations. This post describes how these two methods are used, when they are called, and how they differ from each other. Continue reading