Question

我使用基于https://stackoverflow.com/a/27205784/7468628的动态linq创建了一个SelectExcept。

代码：

public static IQueryable SelectExcept<TSource, TResult>(this IQueryable<TSource> source, List<string> excludeProperties)
    {

        var sourceType = typeof(TSource);
        var allowedSelectTypes = new Type[] { typeof(string), typeof(ValueType) };
        var sourceProperties = sourceType.GetProperties(BindingFlags.Public | BindingFlags.Instance).Where(p => allowedSelectTypes.Any(t => t.IsAssignableFrom(((PropertyInfo)p).PropertyType))).Select(p => ((MemberInfo)p).Name);
        var sourceFields = sourceType.GetFields(BindingFlags.Public | BindingFlags.Instance).Where(f => allowedSelectTypes.Any(t => t.IsAssignableFrom(((FieldInfo)f).FieldType))).Select(f => ((MemberInfo)f).Name);

        var selectFields = sourceProperties.Concat(sourceFields).Where(p => !excludeProperties.Contains(p)).ToArray();

        var dynamicSelect =
                string.Format("new( {0} )",
                        string.Join(", ", selectFields));

        return selectFields.Count() > 0
            ? source.Select(dynamicSelect)
            : Enumerable.Empty<TSource>().AsQueryable<TSource>();
    }

这适用于字段，但从我的对象是表中的对象并与另一个表连接的那一刻起，我在使用SelectExcept时失去了连接值。我怎样才能保持这种联合价值？

Answer 1

嗯，我找到了答案，所以如果有人想知道如何修复它，那就是：

 public static IQueryable SelectExcept<TSource, TResult>(this IQueryable<TSource> source, List<string> excludeProperties)
    {

        var sourceType = typeof(TSource);
        var allowedSelectTypes = new Type[] { typeof(string), typeof(ValueType), typeof(object) };
        var sourceProperties = sourceType.GetProperties(BindingFlags.Public | BindingFlags.Instance).Where(p => allowedSelectTypes.Any(t => t.IsAssignableFrom(((PropertyInfo)p).PropertyType))).Select(p => ((MemberInfo)p).Name);
        var sourceFields = sourceType.GetFields(BindingFlags.Public | BindingFlags.Instance).Where(f => allowedSelectTypes.Any(t => t.IsAssignableFrom(((FieldInfo)f).FieldType))).Select(f => ((MemberInfo)f).Name);
        var selectFields = sourceProperties.Concat(sourceFields).Where(p => !excludeProperties.Contains(p)).ToArray();

        var dynamicSelect =
                string.Format("new( {0} )",
                        string.Join(", ", selectFields));

        return selectFields.Count() > 0
            ? source.Select(dynamicSelect)
            : Enumerable.Empty<TSource>().AsQueryable<TSource>();
    }

您需要选定类型的typeof（对象），否则它不会收集您自己定义的类的字段。

SelectExcept删除已连接的表

1 个答案: