.net bug收集

Dear 丶 2021-09-20 17:22 291阅读 0赞

### 1. 使用\[owned\]时出错 ###

一个model里面定义了一个\[owned\]的属性，例如：

public class Order
    {
        public int Id { get; set; }
        public StreetAddress ShippingAddress { get; set; }
    }
    
    [Owned]
    public class StreetAddress
    {
        public string Street { get; set; }
        public string City { get; set; }
    }

然后在通过api创建Order数据时报错如下：

System.InvalidOperationException: The entity of type 'Order' is sharing the table 'Order' with entities of type 'StreetAddress', but there is no entity of this type with the same key value '{Id: 7a69feac-6d28-4e2c-767a-08d7418bf87a}' that has been marked as 'Added'.
       at Microsoft.EntityFrameworkCore.Update.Internal.CommandBatchPreparer.Validate(Dictionary`2 sharedTablesCommandsMap)
       at Microsoft.EntityFrameworkCore.Update.Internal.CommandBatchPreparer.CreateModificationCommands(IReadOnlyList`1 entries, Func`1 generateParameterName)
       at Microsoft.EntityFrameworkCore.Update.Internal.CommandBatchPreparer.BatchCommands(IReadOnlyList`1 entries)+MoveNext()
       at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(DbContext _, ValueTuple`2 parameters, CancellationToken cancellationToken)
       at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.ExecuteAsync[TState,TResult](TState state, Func`4 operation, Func`4 verifySucceeded, CancellationToken cancellationToken)
       at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(IReadOnlyList`1 entriesToSave, CancellationToken cancellationToken)
       at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
       at Microsoft.EntityFrameworkCore.DbContext.SaveChangesAsync(Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)

root cause：

在创建order数据时，没有StreetAddress的信息。原因在于Owned Types还不支持optional 类型（这里的nullable就是optional类型）。为了避免这个错，我们在创建数据时需要填一个空的object，

参考：

[https://entityframeworkcore.com/knowledge-base/48063630/nullable-owned-types-in-ef-core][https_entityframeworkcore.com_knowledge-base_48063630_nullable-owned-types-in-ef-core]

[https://github.com/aspnet/EntityFramework.Docs/issues/466][https_github.com_aspnet_EntityFramework.Docs_issues_466]

### 2.定义的list类型但传人的json不是数组 ###

报错如下：

Cannot deserialize the current JSON object (e.g. {\"name\":\"value\"}) into type 'System.Collections.Generic.List`1[quote.Models.Item]' because the type requires a JSON array (e.g. [1,2,3]) to deserialize correctly.\nTo fix this error either change the JSON to a JSON array (e.g. [1,2,3]) or change the deserialized type so that it is a normal .NET type (e.g. not a primitive type like integer, not a collection type like an array or List<T>) that can be deserialized from a JSON object. JsonObjectAttribute can also be added to the type to force it to deserialize from a JSON object.\nPath 'items.quantity', line 12, position 19."

解决办发是将想创建的json数据当中的object类型改为数组类型，类似如下结构：

[{}]

### 3. 删除数据时报错 ###

The DELETE statement conflicted with the REFERENCE constraint "FK_QuoteItem_Quote_QuoteId". The conflict occurred in database "SampleDB", table "dbo.QuoteItem", column 'QuoteId'.
    The statement has been terminated.

### 4. 定义owned类型的数据的级联删除 ###

not supported because the owned entity type 'Product' cannot be on the principal side of a non-ownership relationship

原因在于这里用来做principal side的属性本身是一个owned type。因此不能用做在定义级联删除时作为主表。

### 5. 循环引用 ###

报错信息如下：

Newtonsoft.Json.JsonSerializationException: Self referencing loop detected for property 'item' with type 'quote.Models.Items'. Path '[0].items[0].product'.

原因在于在定义one to one的关系的时候，定义如下：

public class Item
        {
            [Key]
            [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
            public Guid itemId { get; set; }
    
            public Product Product { get; set; }
    
    
        }
        
    
     public class Product
        {
            [Key]
            [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
            public Guid productId { get; set; }
    
            [ForeignKey("Item")]
            public Guid itemId { get; set; }
    
            public Item Item { get; set;}
        }

当把product表中的Item字段拿掉之后，不再报错。

### 6.owned type的数据没有被一起更新 ###

在调用put api更新数据时，put的api无法更新owned关系的数据。原因在于：

EF Core将owned类型当作没有identity的实体类型对待，因此指向owned类型的属性被视为navigation属性。 将父实体状态设置为“Modified”不会cascade级联到navigation属性。

但是，使用DbContext或DbSet的Update方法可以实现级联，因此，像下面这样使用时无法更新owned类型数据的：

_context.Entry(contactModelFromRequestBody).State = EntityState.Modified;

而应该用：

_context.Update(contactModelFromRequestBody);

或者也可以手动设置owned类型属性的更新状态。例如：

_context.Entry(quote.Customer).State = EntityState.Modified;

参考：[https://entityframeworkcore.com/knowledge-base/46872428/owned-type-property-not-persisting-for-a-modified-entity-in-ef-core][https_entityframeworkcore.com_knowledge-base_46872428_owned-type-property-not-persisting-for-a-modified-entity-in-ef-core]

### 7. Unable to resolve service for type 'xxxxx' while attempting to activate xxxxx ###

root cause: 想在一个类中使用另一个类的方法，但是没有new这个类的实例，而是想使用依赖注入。于是在调用相应的类时报了这个错误。

解决办法，对于要使用依赖注入的类，需要在startup类当中的configureService方法加入类似如下的逻辑：

services.AddScoped<IDependencyOne, DependencyOne>();    <-- I was missing this line!

### 8.执行命令 dotnet ef database update报错 ###

报错如下：

Could not execute because the specified command or file was not found.
    Possible reasons for this include:
      * You misspelled a built-in dotnet command.
      * You intended to execute a .NET Core program, but dotnet-ef does not exist.
      * You intended to run a global tool, but a dotnet-prefixed executable with this name could not be found on the PATH

解决方法，安装对应版本的.net core. 再执行命令：

dotnet tool install --global dotnet-ef

然后重启Powershell，运行成功

9.The instance of entity type 'Invoice' cannot be tracked because another instance with the same key value for \{'Id'\} is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key  
在update一个entity多次时报错：

this.customTableDbContext.Set<TEntity>().Update(entity);
     this.customTableDbContext.SaveChanges();

解决办法是:

this.customTableDbContext.Set<TEntity>().Update(entity);
     this.customTableDbContext.SaveChanges();
    this.customTableDbContext.Entry(entity).State = EntityState.Detached;

update之后将状态设置为Detached

[https_entityframeworkcore.com_knowledge-base_48063630_nullable-owned-types-in-ef-core]: https://entityframeworkcore.com/knowledge-base/48063630/nullable-owned-types-in-ef-core
[https_github.com_aspnet_EntityFramework.Docs_issues_466]: https://github.com/aspnet/EntityFramework.Docs/issues/466
[https_entityframeworkcore.com_knowledge-base_46872428_owned-type-property-not-persisting-for-a-modified-entity-in-ef-core]: https://entityframeworkcore.com/knowledge-base/46872428/owned-type-property-not-persisting-for-a-modified-entity-in-ef-core