Cannot convert implicity type Syste.Linq.IQueryable<<anonymys type int>> to

Question

I have this SQL query:

SELECT project_id,count(project_id) as vote_count 
from Votes 
group by project_id;

Write it in LINQ syntax:

public int GetCountOfVotes()
{
    using (var db = new SafetyFundDbContext(Options))
    {

        var result = db.Votes
            .GroupBy(vote => vote.ProjectId)
            .Select(group => new
            {
                ProjectID = group.Key,
                Count = group.Count()
            });

        return result;
   }          
}

And C# return error :

Where is the problem?

Answer 1

result is an enumerable of an anonymous type, not a single int. Instead you need to return a single value. Since you need the votes for a single project, you need to tell the function which project by passing in the ID:

public int GetCountOfVotes(int projectId)
{
    using (var db = new SafetyFundDbContext(Options))
    {
        return db.Votes
            .Where(vote => vote.ProjectId == projectId)
            .Count();    
   }          
}

If you need votes for all projects, you need to change the return type to a concrete class, for example:

public class ProjectVotes
{
    public int ProjectID { get; set; }
    public int Votes { get; set; }
}

And your method becomes:

public IEnumerable<ProjectVotes> GetCountOfVotes()
{
    using (var db = new SafetyFundDbContext(Options))
    {
        return db.Votes
            .GroupBy(vote => vote.ProjectId)
            .Select(group => new ProjectVotes
            {
                ProjectID = group.Key,
                Votes = group.Count()
            })
            .ToList();
   }          
}