Expression & lt; Func & lt; TObject, bool & gt; Difference from Func & lt; TObject, bool & gt;, functobject

Difference between Expression <Func <TObject, bool> and Func <TObject, bool>: functobject

Func <TObject, bool> YesDelegate(Delegate)

Expression <Func <TObject, bool> YesExpression

After Expression is compiled, it becomes delegate to run. For example

Expression <Func <int, bool> ex = x => x <100;

Func <int, bool> func = ex.Compile();

Then you can call func:

Func (5) //-returns true

Func (200) //-returns false

Expressions cannot be called directly.

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Case: full database table query caused by incorrect query code.

The Code logic above is to dynamically generate a LINQ query Condition Based on the condition, and pass the Func type variable as a parameter to the Where method.

In fact, the parameter type required by Where is Expression <Func <TSource, bool>.

Solution:

Do not use Func <TSource, bool> or Expression <Func <TSource, bool>.