[SOLVED]: Sorting does not work with dynamic column

Question

4.33/5 (3 votes)

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I have one generic function like:

C#

public TabMasterListViewModel GetTabMasterList(string OrderByColumn, string OrderType, int PageSize, int CurrentPage)
        {
            try
            {
                if ((CurrentPage == 0) || (PageSize == 0))
                    return null;

                IQueryable<TabMaster> query = _tabmasterRepository.GetQueryable();
                TabMasterListViewModel model = new TabMasterListViewModel();
                model.TotalItemCount = query.Count();
                if (model.TotalItemCount == 0)
                    return null;
                model.TotalPageCount = (int)Math.Ceiling((double)model.TotalItemCount / (double)PageSize);
                if (model.TotalPageCount != 1)
                {
                    if (OrderType.ToUpper() == "ASC")
                        query = query.OrderBy(x => x.colID).Skip((CurrentPage - 1) * PageSize).Take(PageSize);
                    else
                        query = query.OrderByDescending(x => x.colID).Skip((CurrentPage - 1) * PageSize).Take(PageSize);
                }
                model.ThisPageItemCount = query.Count();
                model.TabMasterList = new List<TabMasterViewModel>();
                AutoMapper.Mapper.CreateMap<TabMaster, TabMasterViewModel>()
                    .ForMember(dest => dest.colID, opt => opt.MapFrom(src => src.colID));
                model.TabMasterList = AutoMapper.Mapper.Map(query.ToList(), model.TabMasterList);

                return model;
            }
            catch (System.Exception e)
            {
                this.LogError("Error getting the TabMaster list", e);
                return null;
            }
        }

if i am use following line

C#

query = query.OrderBy(x => x.colID).Skip((CurrentPage - 1) * PageSize).Take(PageSize);

then sorting is complete working as aspect.
if i am using OrderByColumn in following line, then sorting dose not work.

C#

if (OrderType.ToUpper() == "ASC")
                        query = query.OrderBy(x => OrderByColumn).Skip((CurrentPage - 1) * PageSize).Take(PageSize);
                    else
                        query = query.OrderByDescending(x => OrderByColumn).Skip((CurrentPage - 1) * PageSize).Take(PageSize);

Please suggest what i am missing?

Thanks,
Imdadhusen

Posted 10-Jun-11 1:51am

Sunasara Imdadhusen

Updated 10-Jun-11 3:05am

v2

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2 solutions

Solution 1

This is because OrderByColumn is just a string. It is unrelated to the values that you are sorting: expression x => OrderByColumn returns the same value for all instances of x, so it makes sense that the sort does not work.

Making it work is a more interesting question: if you are good at reflection[^], you can skip the rest of this answer. If you don't like reflection, you can still do it: replace your sort expression with query.OrderBy(x => ChooseColumn(x, OrderByColumn)), and implement ChooseColumn as follows:

public object ChooseColumn(string columnName, TabMaster x) {
    switch(columnName) {
        case "MyColumn1": return x.MyColumn1;
        case "MyColumn2": return x.MyColumn2;
        case "MyColumn3": return x.MyColumn3;
        default: throw new InvalidOperationException("Unknown: "+columnName);
    }
}

Posted 10-Jun-11 2:45am

dasblinkenlight

Comments

Sunasara Imdadhusen 10-Jun-11 9:03am

good one, but suppose i have 100+ columns then?

dasblinkenlight 10-Jun-11 9:20am

If it's 100+ columns, your best choice is to become good at reflection: that's what the landman-code guy did :-)

Sunasara Imdadhusen 10-Jun-11 9:04am

my vote of 5.

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Sunasara Imdadhusen · Accepted Answer · 2011-06-10T03:03:00

Solution 2

Here is the Excellent solution for the same

http://landman-code.blogspot.com/2008/11/linq-to-entities-string-based-dynamic.html[^]

Posted 10-Jun-11 3:03am

Sunasara Imdadhusen

[SOLVED]: Sorting does not work with dynamic column

2 solutions

Solution 1

Solution 2

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[SOLVED]: Sorting does not work with dynamic column

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Solution 2

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