如果使用 EF Core 的自动映射程序，则不会正确返回 OData @count$top

Question

我正在使用此链接提供的解决方案：自动映射器不适用于实体 EF Core

我的问题是在使用$top时，@odata.count 始终返回 $top 中通知的数字，但应返回总记录的数量。

我知道ODataQueryOptions有一个属性"Count"，但我不知道是否可以用它来解决问题

我在他的问题中使用了以下代码 Дмитрий Краснов 包括伊万·斯托耶夫的解决方案：

有实体：

public class LessonCatalog {
public string Name { get; set; }
public int? ImageId { get; set; }
public virtual Image Image { get; set; }
public virtual ICollection<Lesson> Lessons { get; set; }
}
public class Lesson {
public string Name { get; set; }
public string Description { get; set; }
public int? ImageId { get; set; }
public virtual Image Image { get; set; }
public int LessonCatalogId { get; set; }
public virtual LessonCatalog LessonCatalog { get; set; }
}
Views:
public class LessonView {
public string Name { get; set; }
public string Description { get; set; }
public int? ImageId { get; set; }
public ImageView Image { get; set; }
public int LessonCatalogId { get; set; }
public LessonCatalogView LessonCatalog { get; set; }
}
public class LessonCatalogView {
public string Name { get; set; }
public int? ImageId { get; set; }
public ImageView Image { get; set; }
public IEnumerable<LessonView> Lessons { get; set; }
}

我的地图：

CreateMap<LessonCatalog, LessonCatalogView>()
.ForMember(dest => dest.Image, map => map.ExplicitExpansion())
.ForMember(dest => dest.Lessons, map => map.ExplicitExpansion());
CreateMap<Lesson, LessonView>()
.ForMember(dest => dest.LessonCatalog, map => map.ExplicitExpansion());
In my repository:
protected readonly DbContext _context;
protected readonly DbSet<TEntity> _entities;
public Repository(DbContext context) {
_context = context;
_entities = context.Set<TEntity>();
}
public IEnumerable<TView> GetOData<TView>(ODataQueryOptions<TView> query,
Expression<Func<TEntity, bool>> predicate = null) {
IQueryable<TEntity> repQuery = _entities.AsQueryable();
IQueryable res;
if (predicate != null) repQuery = _entities.Where(predicate);
if (query != null) {
string[] expandProperties = GetExpands(query);
//!!!
res = repQuery.ProjectTo<TView>(Mapper.Configuration, null, expandProperties);
//!!!
var settings = new ODataQuerySettings();
var ofilter = query.Filter;
var orderBy = query.OrderBy;
var skip = query.Skip;
var top = query.Top;
if (ofilter != null) res = ofilter.ApplyTo(res, settings);
if (orderBy != null) res = orderBy.ApplyTo(res, settings);
if (skip != null) res = skip.ApplyTo(res, settings);
if (top != null) res = top.ApplyTo(res, settings);
} else {
res = repQuery.ProjectTo<TView>(Mapper.Configuration);
}
return (res as IQueryable<TView>).AsEnumerable();
}

如果我的查询结果有 1007 条记录，并且我使用

…$count=true&$top=5

计数的结果应为

"@odata.count": 1007

但相反，结果总是

"@odata.count": 5

使用 SQL Server 配置文件，我可以看到"选择计数"包括"顶部"。那么，如何避免这种情况发生呢？

Answer 1

我得到了Github Guy的帮助(感谢@Gennady Pundikov(，现在可以回答这个问题了。

我更改了 GetOData 方法以在应用其他设置之前获取计数：

public IEnumerable<TView> GetOData<TView>(ODataQueryOptions<TView> query,
Expression<Func<TEntity, bool>> predicate = null) {
IQueryable<TEntity> repQuery = _entities.AsQueryable();
IQueryable res;
if (predicate != null) repQuery = _entities.Where(predicate);
if (query != null) {
string[] expandProperties = GetExpands(query);
//!!!
res = repQuery.ProjectTo<TView>(Mapper.Configuration, null, expandProperties);
//!!!
var settings = new ODataQuerySettings();
var ofilter = query.Filter;
var orderBy = query.OrderBy;
var skip = query.Skip;
var top = query.Top;
if (ofilter != null) res = ofilter.ApplyTo(res, settings);
if (query.Count?.Value == true)
{
// We should calculate TotalCount only with filter
// http://docs.oasis-open.org/odata/odata/v4.0/odata-v4.0-part2-url-conventions.html#_Toc371341773
// 4.8 Addressing the Count of a Collection
// "The returned count MUST NOT be affected by $top, $skip, $orderby, or $expand.
query.Request.ODataFeature().TotalCount = ((IQueryable<TView>)res).LongCount();
}
if (top != null) res = top.ApplyTo(res, settings);
if (orderBy != null) res = orderBy.ApplyTo(res, settings);
if (skip != null) res = skip.ApplyTo(res, settings);
} else {
res = repQuery.ProjectTo<TView>(Mapper.Configuration);
}
return (res as IQueryable<TView>).AsEnumerable();
}