Return an object built from various models, web api, EntityFramework 6

Question

Im currently building a web api 2 API using Entity Framework 6. All was going well as a lot of the api calls are just straight through to a single table and return the object as a JSON.

Now my headaches have come with trying to build a single object from various models. I am using Code first.

A Simplified version of the object i want to return is this

{ Name : Brand.Name, CategoryScores : [{CategoryId : 'x', Score : 'x'}]}

These are my current models

[Table("Brands")]
public class BrandModel
{

    [Key]
    public string BrandId { get; set; }
    public string BrandName { get; set; }
}

[Table("CategoryScores")]
public class CategoryScoresModel
{

    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public Guid Id { get; set; }
    public string BrandId { get; set; }
    public string TraqCategoryScore { get; set; }}

public class TraqIndexDTO
{
    public string BrandName { get; set; }
    public IEnumerable<CategoryScoresDTO> CategoryScores { get; set; }

}

public class CategoryScoresDTO
{
    public string CategoryId { get; set; }
    public string TraqCategoryScore { get; set; }
}

Controller the logic in here will be moved out once its working

private AuthContext db = new AuthContext();

public IHttpActionResult Get()
    {
        //var results = this.repository.SelectAll();
        return Ok(GetTraqIndex());
    }
public IEnumerable<TraqIndexDTO> GetTraqIndex()
    {
        var traqIndex = from b in db.Brand
                        select new TraqIndexDTO()
                        {
                            BrandName = b.BrandName,
                            CategoryScores = getCatgoryScoresByBrandId(b.BrandId)
                        };

        return traqIndex;
    }

public IEnumerable<CategoryScoresModelDTO>getCatgoryScoresByBrandId(string brandId)
    {
        var scores = from s in db.CategoryScoresModel
                     where s.BrandId == brandId
                     select new CategoryScoresDTO() {
                         CategoryId = s.CategoryId,
                         TraqCategoryScore = s.TraqCategoryScore
                     };

        return scores;
    }

Currently I am getting this error " getCategoryScoresByBrandId(System.String)' method, and this method cannot be translated into a store expression.""

Any help and guidance or a good example to follow would be much appreciated

Thanks Rob

Uriil · Accepted Answer · 2014-12-24 13:43:22Z

1

Modify GetTraqIndex:

public IEnumerable<TraqIndexDTO> GetTraqIndex()
{
    var traqIndex = db.Brand.ToList().Select(b => new TraqIndexDTO()
                    {
                        BrandName = b.BrandName,
                        CategoryScores = getCatgoryScoresByBrandId(b.BrandId).ToList()
                    }).ToList();

    return traqIndex;
}

edited Dec 24, 2014 at 13:43

answered Dec 24, 2014 at 13:32

Uriil

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5 Comments

Rob Paddock Over a year ago

Thanks but BrandName and Category scores now do not exist in the current context

Rob Paddock Over a year ago

Thats ok much appreciate the help but now i get this getCatgoryScoresByBrandId(b.BrandId) as not available in the current context

Rob Paddock Over a year ago

Sorry my mistake type ;)

Rob Paddock Over a year ago

Thank you so much all working, that drove me nearly over the edge.... So the key was ToList ;)

Uriil Over a year ago

@RobPaddock Accept answer then =)

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