Not able to write proper function in asp.net mvc 3.0

Question

i have one method and it will return IQueryable value

public IQueryable<TabMasterViewModel> Query(Expression<Func<TabMaster, bool>> whereCondition)
{
    IQueryable<TabMaster> tabmasters = _tabmasterRepository.GetQueryable().Where(whereCondition);
    IQueryable<TabMasterViewModel> tabmasterview;
    AutoMapper.Mapper.CreateMap<TabMaster, TabMasterViewModel>()
        .ForMember(dest => dest.colID, opt => opt.MapFrom(src => src.colID));
    tabmasterview = AutoMapper.Mapper.Map(tabmasters, tabmasterview);
    return tabmasterview;
}

and the GetQueryable is like

public IQueryable<T> GetQueryable()
{
    return this.ObjectSet.AsQueryable<T>();
}

but the following line

tabmasterview = AutoMapper.Mapper.Map(tabmasters, tabmasterview);

is giving me an error

Use of unassigned local variable 'tabmasterview'

please suggest me, where is am i wrong?

Vijay Sirigiri · Accepted Answer · 2011-06-10 08:58:09Z

1

To fix the compiler error all you have to do is

 IQueryable<TabMasterViewModel> tabmasterview = null;

But the second argument you are passing to AutoMapper.Mapper.Map(tabmasters, tabmasterview) is always null as tabMasterview has not been intialized. If that is intended you could as well pass "null".

public IQueryable<TabMasterViewModel> Query(Expression<Func<TabMaster, bool>> whereCondition)
        {
            IQueryable<TabMaster> tabmasters = _tabmasterRepository.GetQueryable().Where(whereCondition);

            AutoMapper.Mapper.CreateMap<TabMaster, TabMasterViewModel>()
                  .ForMember(dest => dest.colID, opt => opt.MapFrom(src => src.colID));
            return AutoMapper.Mapper.Map<IQueryable<TabMaster>,  IQueryable<TabMasterViewModel>> (tabmasters);            
        }

EDIT:

The above code answers your question related to compiler error. As for your comments about the runtime error.. modify this line

return AutoMapper.Mapper.Map<IQueryable<TabMaster>,  IQueryable<TabMasterViewModel>> (tabmasters);

to

return AutoMapper.Mapper.Map<IQueryable<TabMaster>,  IEnumerable<TabMasterViewModel>> (tabmasters).AsQueryable<TabMasterViewModel>();

edited Jun 10, 2011 at 8:58

answered Jun 10, 2011 at 7:06

Vijay Sirigiri

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5 Comments

imdadhusen Over a year ago

runtime error like: Unable to cast object of type 'System.Collections.Generic.List1[Models.TabMasterViewModel]' to type 'Linq.IQueryable1[Models.TabMasterViewModel]'. my updated code like 'public IQueryable<TabMasterViewModel> IQueryable<TabMaster> tabmasters = _tabmasterRepository.GetQueryable().Where(whereCondition); IQueryable<TabMasterViewModel> tabmasterview = null; AutoMapper.Mapper.CreateMap<TabMaster, TabMasterViewModel>() .ForMember(dest => dest.colID, opt => opt.MapFrom(src => src.colID)); tabmasterview = AutoMapper.Mapper.Map(tabmasters, tabmasterview); return tabmasterview;

Vijay Sirigiri Over a year ago

Yes. Check the updated code. Basically you are asking the AutoMapper to map an IQuerable of TabMaster's to Iquerable TabMasterViewModel.

imdadhusen Over a year ago

same error comes again: Unable to cast object of type 'System.Collections.Generic.List1[CAFM.Business.Models.TabMasterViewModel]' to type 'System.Linq.IQueryable1[CAFM.Business.Models.TabMasterViewModel]'.

Vijay Sirigiri Over a year ago

I'd added code under edit section which should solve the run-time issue.

imdadhusen Over a year ago

Hi dude you are absolutely right and now i am getting 100% success. Thanks a lot. my vote is +1

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