public static async Task <PagedListResult <TOutput> > PaginateListResultAsync <TInput, TOutput>(
this IQueryable <TInput> queryable,
OffsetBasedContinuationToken continuationToken,
int pageSize,
Func <TInput, TOutput> conversion)
{
int offset = Math.Clamp(continuationToken.Offset, 0, int.MaxValue);
var data = await queryable.Skip(offset)
.Take(pageSize + 1)
.ToListAsync();
var list = data.Select(x => conversion(x))
.Where(x => x != null)
.ToList();
OffsetBasedContinuationToken?token = null;
if (list.Count > pageSize)
{
token = new OffsetBasedContinuationToken
{
Offset = offset + pageSize,
};
list.RemoveAt(list.Count - 1); // keep it for the next page
}
return(new PagedListResult <TOutput> {
Items = list, ContinuationToken = token?.IntoToken()
});
}
public static async Task <CursorListResult <TOutput> > CursorQueryAsync <TInput, TOutput>(
this IQueryable <TInput> queryable,
string?cursor,
int pageSize,
Func <TInput, TOutput> conversion)
where TInput : notnull
where TOutput : notnull
{
int offset = 0;
if (cursor != null)
{
var token = new OffsetBasedContinuationToken(cursor);
offset = Math.Clamp(token.Offset, 0, int.MaxValue);
}
var data = await queryable.Skip(offset)
.Take(pageSize + 1)
.ToListAsync();
var list = data
.Select(x => conversion(x))
.ToList();
if (list.Count > pageSize)
{
var token = new OffsetBasedContinuationToken
{
Offset = offset + pageSize,
};
list.RemoveAt(list.Count - 1); // keep it for the next page
return(new CursorListResult <TOutput>(list, token.IntoToken()));
}
else
{
return(new CursorListResult <TOutput>(list, null));
}
}