用值展平表达式参数[重复]

我想到了这个,它似乎起了作用:

protected class ParameterReplacer : ExpressionVisitor
{
    private ParameterExpression parameterExpression;
    private string newValue;

    public ParameterReplacer(ParameterExpression parameterExpression, string newValue)
    {
        this.parameterExpression = parameterExpression;
        this.newValue = newValue;
    }

    public override Expression Visit(Expression node)
    {
        if (node == parameterExpression)
            return Expression.Constant(this.newValue);

        return base.Visit(node);
    }
}

在我的代码中,我是这样使用的:

var replacer = new ParameterReplacer(FilterExp.Parameters[1], Filter);
var newBody = replacer.Visit(FilterExp.Body);
var exp = Expression.Lambda<Func<T, bool>>(newBody, FilterExp.Parameters[0]);
return SourceData.Where(exp);