public static Expression GetOrderByMethod <T>(this Expression expression,
ODataQueryOptions <T> options, ODataSettings oDataSettings = null)
{
if (NoQueryableMethod(options, oDataSettings))
{
return(null);
}
return(expression.GetQueryableMethod
(
options.Context,
options.OrderBy?.OrderByClause,
typeof(T),
options.Skip?.Value,
GetPageSize()
));
int?GetPageSize()
{
if (oDataSettings?.PageSize == null && options.Top == null)
{
return(null);
}
if (options.Top == null)
{
return(oDataSettings.PageSize);
}
else if (oDataSettings?.PageSize == null)
{
return(options.Top.Value);
}
return(options.Top.Value < oDataSettings.PageSize
? options.Top.Value
: oDataSettings.PageSize);
}
}
private static bool NoQueryableMethod(ODataQueryOptions options, ODataSettings oDataSettings) => options.OrderBy is null && options.Top is null && options.Skip is null && oDataSettings?.PageSize is null;
/// <summary>
/// Returns a lambda expresion for order and paging expressions
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="options"></param>
/// <param name="oDataSettings"></param>
/// <returns></returns>
public static Expression <Func <IQueryable <T>, IQueryable <T> > > GetQueryableExpression <T>(this ODataQueryOptions <T> options, ODataSettings oDataSettings = null)
{
if (NoQueryableMethod(options, oDataSettings))
{
return(null);
}
ParameterExpression param = Expression.Parameter(typeof(IQueryable <T>), "q");
return(Expression.Lambda <Func <IQueryable <T>, IQueryable <T> > >
(
param.GetOrderByMethod(options, oDataSettings), param
));
}
