How to Manually Set Primary Keys in Entity Framework without Errors?

Avoiding Primary Key Conflicts in Entity Framework's Code-First Approach

In Entity Framework's code-first development, manually specifying primary keys can sometimes conflict with automatic key generation. This often leads to errors when trying to insert data. Let's explore how to avoid these issues.

One method involves disabling automatic key generation:

<code class="language-csharp">modelBuilder.Entity<Event>().Property(e => e.EventID).HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);</code>

However, this can trigger the error:

<code>Cannot insert explicit value for identity column in table 'Events' when IDENTITY_INSERT is set to OFF.</code>

The solution lies in correctly defining the primary key property within your POCO class (e.g., Event). Ensure your property declaration includes both Key and Required attributes:

<code class="language-csharp">[Key, Required]
public int EventID { get; set; }</code>

Alternatively, you can achieve the same result using these attributes:

<code class="language-csharp">[Key]
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public int EventID { get; set; }</code>

This approach is compatible with both Entity Framework and Entity Framework Core, providing a reliable way to manage manually assigned primary keys.

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