Expression.Like in C#

例如：x => x.Name =“g”

我有这样的代码块

public Expression<Func<TEntity,bool>> SearchExpression()
{
    var c = new ConstantExpression[_paramList.Count];
    var b = new BinaryExpression[_paramList.Count];
    BinaryExpression comparisonExpression = null;

    var entity = Expression.Parameter(typeof(TEntity));

    for (int i = 0; i < _paramList.Count; i++)
    {
        var value = Convert.ChangeType(_paramList[i].Item2 /*"g"*/,_paramList[i].Item3 /*System.String*/);
        c[i] = Expression.Constant(value); //"g"

        // PROBLEM IS HERE
        b[i] = Expression.Equal(Expression.Property(entity,_paramList[i].Item1 /*Name*/,c[i]);
        // PROBLEM IS HERE



    }
    _paramList.Clear();
    comparisonExpression = b.Aggregate(Expression.And);
    return Expression.Lambda<Func<TEntity,bool>>(comparisonExpression,entity);
}

像魅力一样工作,但我需要Expression.Like(喜欢“g”不等于“g”)

Expression.Like(Expression.Property(entity,_paramList[i].Item1),c[i])

但是C#表达式树不支持Like方法

更新：

我写了这样的东西：

Expression.Call(Expression.Property(entity,typeof(String).getmethod("Contains"),new Expression[] { c[i] });

但我需要BinaryExpression而不是MethodCallExpression

解决方法

您可以通过在方法调用上添加equals表达式来使代码工作,如下所示：

b[i] = Expression.Equal(
        Expression.Call(Expression.Property(entity,typeof (String).getmethod("Contains"),new Expression[] {c[i]}),Expression.Constant(true));

在伪代码中,它读作：

b[i] = entity => entity.someProperty.Contains(c[i]) == true;

这将为您返回二进制表达式.