dotnet config_error ai_generated true

System.InvalidOperationException: Cannot create a DbSet for 'X' because a DbSet with the same entity type already exists.

ID: dotnet/ef-core-multiple-navigation-sets

Also available as: JSON · Markdown · 中文
90%Fix Rate
90%Confidence
1Evidence
2023-05-10First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
EF Core 6.0 active — — —
EF Core 7.0 active — — —
EF Core 8.0 active — — —

Root Cause

The DbContext class defines two or more DbSet properties that map to the same entity type, causing ambiguity in EF Core's internal model building.

generic

中文

DbContext 类定义了两个或更多映射到同一实体类型的 DbSet 属性，导致 EF Core 内部模型构建产生歧义。

Official Documentation

https://learn.microsoft.com/en-us/ef/core/modeling/entity-types

Workarounds

  1. 95% success Remove the duplicate DbSet property from the DbContext class. Keep only one declaration for the entity type. For example, remove either 'public DbSet<Order> Orders { get; set; }' or 'public DbSet<Order> SalesOrders { get; set; }'. 
    Remove the duplicate DbSet property from the DbContext class. Keep only one declaration for the entity type. For example, remove either 'public DbSet<Order> Orders { get; set; }' or 'public DbSet<Order> SalesOrders { get; set; }'.
  2. 80% success If you need multiple query surfaces, use separate DbContext classes for different bounded contexts. 
    If you need multiple query surfaces, use separate DbContext classes for different bounded contexts.

中文步骤

  1. 从 DbContext 类中移除重复的 DbSet 属性。只保留一个实体类型声明。例如，移除 'public DbSet<Order> Orders { get; set; }' 或 'public DbSet<Order> SalesOrders { get; set; }' 中的一个。
  2. 如果需要多个查询接口，为不同的限界上下文使用单独的 DbContext 类。

Dead Ends

Common approaches that don't work:

  1. 70% fail

    This removes the property from the context entirely, losing the ability to query that entity through that property.

  2. 50% fail

    This duplicates code and does not solve the core issue of duplicate DbSet definitions.