private static Expression GetThenBy(
Expression queryExpression,
OrderingField field)
{
string methodName = field.IsDescending ? nameof(Queryable.ThenByDescending) : nameof(Queryable.ThenBy);
return(Expression.Call(
typeof(Queryable),
methodName,
new System.Type[] { typeof(TDbObject), field.Type },
queryExpression,
Expression.Lambda(ParameterReplacer.RepalceParameter(field.Expression), DbItem)));
}
public static Expression BuildAutoFilter(
Expression mappingExpression,
OrderingFields orderingFields,
TOrder after)
{
var filters = new List <FilterValue>(capacity: orderingFields.Fields.Count);
foreach (OrderingField field in orderingFields.Fields)
{
var value = orderingFields.IsDirect ? after : GetValue(after, field);
filters.Add(new FilterValue
{
Expression = field.Expression,
Value = Expression.Constant(value),
IsLower = field.IsDescending,
});
}
Expression filter = null;
for (var current = 0; current < filters.Count; current++)
{
FilterValue currentValue = filters[current];
Expression currentFilter = null;
for (var prev = 0; prev < current; prev++)
{
FilterValue prevValue = filters[prev];
Expression equal = Expression.Equal(prevValue.Expression, prevValue.Value);
currentFilter = currentFilter != null?Expression.AndAlso(currentFilter, equal) : equal;
}
Expression compare = GreateCompareExpression(currentValue);
currentFilter = currentFilter != null?Expression.AndAlso(currentFilter, compare) : compare;
filter = filter != null?Expression.OrElse(filter, currentFilter) : currentFilter;
}
return(ParameterReplacer.RepalceParameter(filter));
}