Why Does Entity Framework Throw an Error When Inserting into Identity Columns?

Entity Framework Error: Inserting Explicit Values into Identity Columns

Problem:

When using Entity Framework (EF), an error occurs while attempting to insert values into a table with an identity column:

Cannot insert explicit value for identity column in table 'GroupMembers_New' when IDENTITY_INSERT is set to OFF.

Analysis:

EF is designed to automatically generate identity values for columns marked as such in the database. However, the error suggests that the code is attempting to assign an explicit value to the column.

Solution:

To resolve this issue, ensure that the following conditions are met:

1. Update the EDMX file: Verify that the EDMX file accurately reflects the database schema. The "IsDbGenerated" attribute for the identity column should be set to "true" in the designer file. If it's not, add it manually.
2. Avoid explicit value assignment: The code should not explicitly assign a value to the identity column. Instead, allow EF to handle the automatic generation.
3. Database changes: If the database schema has been modified, update the code to reflect those changes. This may involve modifying the EDMX file, regenerating the code, or manually updating the relevant properties.

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