无法从IEnumerable <t>转换为IEnumerable <t> </t> </t>

时间:2014-11-09 04:42:20

标签: c# linq generics ienumerable mscorlib

我最近一直处于前端编程的世界,但我正在为我正在进行的项目重新投入C#。我正在定义一些模型和通用功能,并收到以下错误:

  

错误3参数2:无法从'System.Collections.Generic.IEnumerable<T> [c:\ Program Files(x86)\ Reference Assemblies \ Microsoft \ Framework.NETFramework \ v4.5 \ mscorlib.dll]'转换为'System.Collections.Generic.IEnumerable<T> [c:\ Program Files(x86)\ Reference Assemblies \ Microsoft \ Framework.NETFramework \ v4.5 \ mscorlib.dll]'

错误来自以下函数中的return语句:

public static PagedResult<T> Create<T, TEntity>(IOrderedQueryable<TEntity> query, PagedRequest pagedRequest, Func<TEntity, T> converter)
        where T : class
    {
        var count = query.Count();

        if (pagedRequest.SortInfo.Fields.Any())
        {
            var firstPass = true;
            foreach (var sortOrder in pagedRequest.SortInfo.Fields)
            {
                if (firstPass)
                {
                    firstPass = false;
                    query = sortOrder.Direction == SortDirection.Ascending
                                ? query.OrderBy(sortOrder.Field) :
                                  query.OrderByDescending(sortOrder.Field);
                }
                else
                {
                    query = sortOrder.Direction == SortDirection.Ascending
                                ? query.ThenBy(sortOrder.Field) :
                                  query.ThenByDescending(sortOrder.Field);
                }
            }
        }

        query = (IOrderedQueryable<TEntity>) query.Skip((pagedRequest.Page - 1) * pagedRequest.PageSize).Take(pagedRequest.PageSize);

        var list = new List<T>();
        foreach (var entity in query)
        {
            list.Add(converter(entity));
        }

        return Create(pagedRequest, list.AsEnumerable(), count);
    }

和创建功能:

static public PagedResult<T> Create(PagedRequest request, IEnumerable<T> data, long totalCount)
    {
        var result = new PagedResult<T> {Status = ResultStatus.Successful, Data = data.ToArray()};

        result.Count = result.Data.Count();
        result.TotalCount = totalCount;

        result.Page.Index = request.Page;
        result.Page.Size = request.PageSize;
        if (result.Page.Size > 0)
        { result.Page.Count = (long)Math.Ceiling((double)totalCount / result.Page.Size); }

        return result;
    }

似乎无法让编译时错误消失。有人对如何解决这个问题有任何想法吗?

1 个答案:

答案 0 :(得分:0)

感谢@JeffMercado,解决方案非常简单。

我的第二个Create函数的方法签名必须是:

static public PagedResult<T> Create<T>(PagedRequest request, IEnumerable<T> data, long totalCount)

而不是:

static public PagedResult<T> Create(PagedRequest request, IEnumerable<T> data, long totalCount)
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