C＃是否有DataBinder.Eval的快速​​版本？

如何解决C＃是否有DataBinder.Eval的快速​​版本？

| 我正在寻找是否存在ASP.NET的System.Web.UI.DataBinder.Eval（）的快速版本？ 理想情况下，可以编译为Func的东西可以稍后缓存并调用，例如：

Func<object,string> expr = CompileDataBinder(typeof(Model),\"model.Pocoproperty.Name\");
string propertyName = expr(model);

有人知道这种野兽是否存在吗？ 附言我没有使用ASP.NET，并且希望它能在正常的C＃中工作     

解决方法

我看的越多，我想说的越多：

Func<Model,string> expr = model => model.PocoProperty.Name;

如果您需要基于字符串的字符串，那么

Expression

API很公平。

class Program
{
    static void Main(string[] args)
    {
        Func<object,string> expr = CompileDataBinder(typeof(Model),\"PocoProperty.Name\");

        var model = new Model { PocoProperty = new ModelPoco { Name = \"Foo\" } };

        string propertyName = expr(model);
    }
    static Func<object,string> CompileDataBinder(Type type,string expr)
    {
        var param = Expression.Parameter(typeof(object));
        Expression body = Expression.Convert(param,type);
        var members = expr.Split(\'.\');
        for (int i = 0; i < members.Length;i++ )
        {
            body = Expression.PropertyOrField(body,members[i]);
        }
        var method = typeof(Convert).GetMethod(\"ToString\",BindingFlags.Static | BindingFlags.Public,null,new Type[] { body.Type },null);
        if (method == null)
        {
            method = typeof(Convert).GetMethod(\"ToString\",new Type[] { typeof(object)},null);
            body = Expression.Call(method,Expression.Convert(body,typeof(object)));
        }
        else
        {
            body = Expression.Call(method,body);
        }

        return Expression.Lambda<Func<object,string>>(body,param).Compile();
    }
}

class Model
{
    public ModelPoco PocoProperty { get; set; }
}
class ModelPoco
{
    public string Name { get; set; }
}

    ,以下是一些应该帮助您入门的内容：

using System;
using System.Diagnostics;
using System.Linq;
using System.Linq.Expressions;


class Person
{
    public int Id { get; set; }
    public FullName FullName { get; set; }
}

class FullName
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}


class Program
{
    static void Main(string[] args)
    {
        Person model = new Person
        {
            Id = 123,FullName = new FullName
            {
                FirstName = \"Duncan\",LastName = \"Smart\",}
        };

        var nameBinder = CompileDataBinder<Person,string>(\"model.FullName.FirstName\");
        string fname = nameBinder(model);
        Debug.Assert(fname == \"Duncan\");

        // Note how here we pretend we don\'t know TProp type
        var idBinder = CompileDataBinder<Person,object>(\"model.Id\");
        object id = idBinder(model);
        Debug.Assert(id.Equals(123));
    }

    static Func<TModel,TProp> CompileDataBinder<TModel,TProp>(string expression)
    {
        var propNames = expression.Split(\'.\');

        var model = Expression.Parameter(typeof(TModel),\"model\");

        Expression body = model;
        foreach (string propName in propNames.Skip(1))
            body = Expression.Property(body,propName);
        //Debug.WriteLine(prop);

        if (body.Type != typeof(TProp))
            body = Expression.Convert(body,typeof(TProp));

        Func<TModel,TProp> func = Expression.Lambda<Func<TModel,TProp>>(body,model).Compile();
        //TODO: cache funcs
        return func;
    }
}