实体框架 - 选择特定的列(Entity Framework - Selecting specifi

我有一个链接一个地方和排序依据子句两个表查询成功，但我想添加到只选择特定的列，而不是让一切恢复。

PART 1当我尝试这个我上线的OrderBy语法错误，如果我删除的排序依据行语法错误移动到哪里行。

错误3无法隐式转换类型“System.Linq.IOrderedQueryable”到“System.Linq.IQueryable”。一个显式转换存在（是否缺少强制转换？）

            IQueryable<VendorProfile> query = _db.VendorProfiles
            .Include("VendorCategories")
            .Include("VendorsSelected")
            .Select(s => new  { s.ProfileID, s.Name, s.CompanyName, s.City, s.State, s.DateCreated, s.VendorsSelected, s.VendorCategories })
            .Where(x => x.VendorsSelected.Select(s => s.UserName).Contains(HttpContext.Current.User.Identity.Name))
            .OrderBy(x => x.DateCreated);

       if (criteria.name != string.Empty)
            query = query.Where(v => v.Name.Contains(criteria.name));
        if (criteria.company != string.Empty)
            query = query.Where(v => v.CompanyName.Contains(criteria.company));
        if (criteria.startDate != null && criteria.endDate != null)
            query = query.Where(v => v.DateCreated > criteria.startDate && v.DateCreated < criteria.endDate);
        if (criteria.categories != null && !criteria.categoryMatchAll)
            query = query.Where(v => criteria.categories.AsQueryable().Any(cat => v.VendorCategories.Select(vendCat => vendCat.CategoryID).Contains(cat)));
        if (criteria.categories != null && criteria.categoryMatchAll)
            query = query.Where(v => criteria.categories.AsQueryable().All(cat => v.VendorCategories.Select(vendCat => vendCat.CategoryID).Contains(cat)));
        if (criteria.minorityType != null)
            query = query.Where(v => v.MinotiryOwned == criteria.minorityType);
        if (criteria.diversityClass != null)
            query = query.Where(v => v.DiversityClassification == criteria.diversityClass);

        return query.ToList();

第2部分我也想知道如果我能提取选中的列到视图模型类，所以我厌倦了这一点，我在排序依据线上得到与上述相同的结果

错误4无法隐式转换类型“System.Linq.IOrderedQueryable”到“System.Linq.IQueryable”。一个显式转换存在（是否缺少强制转换？）

Answer 1:

回答

我想你帮我偶然发现的事实，类型不匹配。使得IQueryable的类型和选择新的类型和返回类型相同，使语法快乐。使用VAR不喜欢。

public IEnumerable<BrowseVendorModel> SearchVendors(CustomSearchModel criteria)
{
    IQueryable<BrowseVendorModel> query = _db.VendorProfiles
        .Include("VendorCategories")
        .Include("VendorsSelected")
        .Select(s => new BrowseVendorModel
        {
            ProfileID = s.ProfileID,
            Name = s.Name,
            CompanyName = s.CompanyName,
            City = s.City,
            State = s.State,
            DateCreated = s.DateCreated,
            VendorsSelected = s.VendorsSelected,
            VendorCategories = s.VendorCategories
        })
        .Where(x => x.VendorsSelected.Select(s => s.UserName).Contains(HttpContext.Current.User.Identity.Name))
        .OrderBy(x => x.DateCreated);

    if (criteria.name != string.Empty)
        query = query.Where(v => v.Name.Contains(criteria.name));
    if (criteria.company != string.Empty)
        query = query.Where(v => v.CompanyName.Contains(criteria.company));
    if (criteria.startDate != null && criteria.endDate != null)
        query = query.Where(v => v.DateCreated > criteria.startDate && v.DateCreated < criteria.endDate);
    if (criteria.categories != null && !criteria.categoryMatchAll)
        query = query.Where(v => criteria.categories.AsQueryable().Any(cat => v.VendorCategories.Select(vendCat => vendCat.CategoryID).Contains(cat)));
    if (criteria.categories != null && criteria.categoryMatchAll)
        query = query.Where(v => criteria.categories.AsQueryable().All(cat => v.VendorCategories.Select(vendCat => vendCat.CategoryID).Contains(cat)));
    if (criteria.minorityType != null)
        query = query.Where(v => v.MinotiryOwned == criteria.minorityType);
    if (criteria.diversityClass != null)
        query = query.Where(v => v.DiversityClassification == criteria.diversityClass);

    return query;
}