Why Does Entity Framework Throw 'The entity type is not part of the model for the current context' and How Can I Fix It?

Model Mapping Error in Entity Framework

When using the Code-First approach in Entity Framework, it is crucial to ensure that the model is correctly mapped to the database. One common error encountered is "The entity type is not part of the model for the current context."

This error typically occurs when the DbContext is not aware of the entity type being accessed or modified. To resolve this issue, you need to explicitly map the entity to the database table in the DbContext.

For the provided code, the solution lies in overriding the OnModelCreating method in the custom DimensionWebDbContext class:

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

By specifying the table name in the ToTable method, you are instructing the DbContext that the Estate entity should be mapped to the "Estate" table in the database.

Without this explicit mapping, Entity Framework assumes that the entity maps to a table with the same name as its class name (Estate in this case). Since the database has not yet been initialized, it does not contain a table with that name, leading to the error.

By correctly mapping the entity, Entity Framework can identify the table to interact with, resolving the error and allowing the insertion and modification of entities from the repository.

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