How to Avoid 'Cannot insert explicit value for identity column' Errors When Manually Setting Primary Keys in Entity Framework?

Addressing Manual Primary Key Entry Issues in Entity Framework

Manually assigning primary keys in Entity Framework can lead to database-generated key errors. This article outlines a solution using attributes to avoid these problems.

Directly using the [NotMapped] attribute is discouraged. While DatabaseGeneratedOption.None seems like a viable alternative to prevent automatic key generation, it often throws a "Cannot insert explicit value for identity column" error.

The solution involves enabling explicit insertion into identity columns using the IDENTITY_INSERT table option:

<code class="language-sql">ALTER TABLE Event SET IDENTITY_INSERT ON;</code>

This resolves the conflict. Alternatively, attributes provide a cleaner approach:

<code class="language-csharp">using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

[Key]
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public int EventID { get; set; }</code>

This attribute-based method is compatible with Entity Framework Core. By employing either DatabaseGeneratedOption.None or the attribute approach, developers can effectively manage manual primary key assignments within Entity Framework.

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