转换表达式 <Func<TProperty> &gt;到功能 <TObject, TProperty> 在哪里知道TObject

Question

I'm trying to convert an:

Expression<Func<TProperty>>

to a

Func<TObject, TProperty>

Where TObject is known and exposes the property expressed by the Expression. For this I imagine have to manipulate the Expression, combine it with the TObject type parameter in a new Expression, and compile.

Edit: Example input and output

class SomeType
{
   public int Number { get; set; }

   public Func<TObject, TProperty> FuncConverter<TObject, TProperty>(Expression<Func<TProperty>>)
   {
       // ???      
   }

   public void test()
   {
       Func<SomeType, int> outputFunc = FuncConverter<SomeType, int>(inputExpression);
   }
}

An expression I expect as input:

Expression<Func<int>> inputExpression = () => Number;

This expression points to the Number property on SomeType

A Func delegate that I expect as output:

Func<SomeType, int> outputFunc = type => type.Number;

End Edit

The problem is, I have no idea to how to do that. I would really appreciate some (references to) accessible information on manipulating Lambda expressions as I have not yet come across any.

Answer 1

I found an answer to my question:

Func<TObject, TProp> Converter<TObject, TProp>(Expression<Func<TProp>> propertyExpression )
    {
        MemberExpression member = propertyExpression.Body as MemberExpression;

        // Get the Property information of the propertyExpression memberExpression
        var property = member.Member as PropertyInfo;

        // Get the Declaring type information from member expression (equivalent to TObject)
        var type = member.Member.DeclaringType;

        // Define the source Parameter for the new Func delegate
        var param = Expression.Parameter(type, "source");
        var source = Expression.Convert(param, type);

        // Get the property on the source
        var get = Expression.MakeMemberAccess(source, property);
        var convert = Expression.Convert(get, typeof(TProp));

        // Construct the Expression
        var lambda = Expression.Lambda<Func<TObject, TProp>>(convert, param);

        // Compile to get the Func delegate type
        return lambda.Compile();
    }

I found the information here: link

Slightly adapted it to solve my problem. Thanks to all commenters...