/// <summary>
/// 从全量数据生成分页数据
/// </summary>
/// <param name="source">源数据</param>
/// <param name="para">分页数据</param>
/// <returns>分页后的数据</returns>
public static DataResult <T> ToODataResult <T>(this IQueryable <T> source, IODataParameter para)
{
Checker.NotNull(source, nameof(source));
Checker.CheckODataParameter(para, nameof(para));
int count = 0;
if (para.Count)
{
count = source.Count();
}
IList <T> result;
if (para == null)
{
result = source.ToList();
}
else
{
var orders = para.GetOrderings();
result = ODataQuery(source, para.Top, para.Skip, orders).ToList();
}
return(new DataResult <T>()
{
Count = count, Result = result,
});
}
/// <summary>
/// 获得排序字段集合
/// </summary>
/// <param name="para"></param>
/// <returns></returns>
public static IReadOnlyDictionary <string, Direction> GetOrderings(this IODataParameter para)
{
if (para is ODataParameter opara)
{
return(opara.Orderings);
}
return(ODataParameter.ToOrderingDictionary(para.OrderBy));
}
/// <summary>
/// OData查询，支持 top, skip, orderby
/// </summary>
/// <typeparam name="T">数据源类型</typeparam>
/// <param name="query">数据源</param>
/// <param name="para">OData参数</param>
/// <returns></returns>
public static IQueryable <T> ODataQuery <T>(this IQueryable <T> query, IODataParameter para)
{
Checker.NotNull(query, nameof(query));
Checker.CheckODataParameter(para, nameof(para));
var orders = para.GetOrderings();
return(ODataQuery(query, para.Top, para.Skip, orders));
}
/// <summary>
/// 检查 <see cref="IODataParameter"/>
/// </summary>
/// <param name="parameter"></param>
/// <param name="paraName"></param>
public static void CheckODataParameter(IODataParameter parameter, string paraName)
{
NotNull(parameter, paraName);
if (parameter.Top < 0)
{
throw new ArgumentException(TopMustNonNegativeInteger);
}
if (parameter.Skip < 0)
{
throw new ArgumentException(SkipMustNonNegativeInteger);
}
}
/// <summary>
/// 从全量数据生成OData数据
/// </summary>
/// <param name="source"></param>
/// <param name="para">分页数据</param>
/// <param name="cancellationToken"><see cref="CancellationToken"/></param>
/// <returns></returns>
public static async Task <DataResult <T> > ToODataResultAsync <T>(this IQueryable <T> source, IODataParameter para, CancellationToken cancellationToken = default)
{
Checker.NotNull(source, nameof(source));
Checker.CheckODataParameter(para, nameof(para));
int count = 0;
if (para.Count)
{
count = await source.CountAsync(cancellationToken);
}
if (para.Top <= 0)
{
return(new DataResult <T>()
{
Count = count, Result = Enumerable.Empty <T>().ToList(),
});
}
IList <T> result = await source.ODataQuery(para).ToListAsync(cancellationToken);
return(new DataResult <T>()
{
Count = count, Result = result,
});
}
