无法创建常量值类型。(Unable to create a constant value of type . Only primitive types or enumeration types are

无法创建常量值类型。(Unable to create a constant value of type . Only primitive types or enumeration types are supported in this context)

我有以下方法进行通用检查，

public virtual bool CheckExist(T entity) { var context = new eTRdataEntities(); IQueryable<T> dbQuery = context.Set<T>(); if (dbQuery.Any(e => e == entity)) { return true; } return false; }

但是它返回异常：

无法创建常量值类型。 在此上下文中仅支持原始类型或枚举类型。

请指教，

非常感谢，

I have the following method for a generic check exist,

public virtual bool CheckExist(T entity) { var context = new eTRdataEntities(); IQueryable<T> dbQuery = context.Set<T>(); if (dbQuery.Any(e => e == entity)) { return true; } return false; }

However it returns the exception:

Unable to create a constant value of type . Only primitive types or enumeration types are supported in this context.

Please advice,

Many Thanks,

最满意答案

尝试通过接受方法名称旁边的类型T来更改代码，如下所示：

public virtual bool CheckExist<T>(T entity) { var context = new eTRIKSdataEntities(); IQueryable<T> dbQuery = context.Set<T>(); if (dbQuery.Any(e => e == entity)) { return true; } return false; }

您可能还希望仅将类型限制为类，如下所示：

public virtual bool CheckExist<T>(T entity) where T : class { var context = new eTRIKSdataEntities(); IQueryable<T> dbQuery = context.Set<T>(); if (dbQuery.Any(e => e == entity)) { return true; } return false; }

Try changing the code by taking in the type T next to the method name, like this:

public virtual bool CheckExist<T>(T entity) { var context = new eTRIKSdataEntities(); IQueryable<T> dbQuery = context.Set<T>(); if (dbQuery.Any(e => e == entity)) { return true; } return false; }

You may also want to restrict the type to classes only, like this:

public virtual bool CheckExist<T>(T entity) where T : class { var context = new eTRIKSdataEntities(); IQueryable<T> dbQuery = context.Set<T>(); if (dbQuery.Any(e => e == entity)) { return true; } return false; }