Why Does Entity Framework Throw 'The entity type is not part of the model for the current context'?

Understanding "The entity type is not part of the model for the current context" Exception

In Entity Framework, when attempting to access or modify an entity, one may encounter the exception, "The entity type is not part of the model for the current context." This error typically arises when Entity Framework cannot find the specified entity type in the context's model, resulting in the inability to perform operations on that entity.

Root Cause

The root cause of this exception often lies in a disconnect between the entities defined in the code and the entities recognized by the context. In the provided code sample, the "Estate" entity appears to be defined as a class, but without explicit mapping, Entity Framework may not be aware of its existence within the model.

Solution

To resolve this issue, you can provide explicit mapping for the "Estate" entity in the context's "OnModelCreating" override method:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Estate>().ToTable("Estate");
}

This mapping informs Entity Framework that the "Estate" entity should be associated with a database table named "Estate."

PostgreSQL Compatibility

For PostgreSQL compatibility, ensure that the database initializer is set correctly. In the provided code, the following setting may be required:

Database.SetInitializer<DimensionWebDbContext>(null);

Custom Entity Mappings

Instead of hardcoding the mappings in "OnModelCreating," you can also utilize separate "EntityTypeConfiguration" classes for more structured and extensible entity mappings.

By explicitly mapping entities, you establish a clear and maintainable relationship between your code and the underlying database, avoiding the "The entity type is not part of the model" error.

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