Get another class from LINQ to SQL query

Question

I am a little weak in LINQ to SQL so will try to explain my problem.

I have a method as follows (simplified to explain it better):

public static List<ic_ProductData> GetCompleteSimilarProductsWithApplyButton(InfoChoiceAdminDataContext db)
{

    var products = (from
                        p in db.ic_ProductDatas
                    join proddef in db.ic_ProductDefs on p.ProductDefId equals proddef.ProductDefId

                    select p
                        ).ToList();

    return products;
}

ic_ProductData and ic_ProductDefs are tables in my database

The ic_ProductData class contains a manually created property as:

public ic_ProductDef RelatedProductDef { get; set; }

I want to modify the above LINQ to SQL query so that I can populate this property.

Please note I do not want another call to the database.

Also there are a lot of properties in ic_ProductData so I want to avoid mapping each and every property

Something to the effect of the following (obviously the below is wrong):

public static List<ic_ProductData> GetCompleteSimilarProductsWithApplyButton(InfoChoiceAdminDataContext db)
{

    var products = (from
                        p in db.ic_ProductDatas
                    join proddef in db.ic_ProductDefs on p.ProductDefId equals proddef.ProductDefId
                    //trying to change here
                    select new ic_ProductData
                    {
                        //do something with p here so that all the properties of new object gets filled
                        // avoid mapping of properties here
                        RelatedProductDef = proddef
                    }
                        ).ToList();

    return products;
}

With my limited knowledge I am stuck here.

Please help!

Thanks in advance!

Tom Wuyts · Accepted Answer · 2015-11-26 13:11:10Z

2

You can do something like this:

var query = (from p in db.ic_ProductDatas
                join proddef in db.ic_ProductDefs on p.ProductDefId equals proddef.ProductDefId
                select new 
                {
                    ProductData = p,
                    Def = proddef
                }).ToList();

List<ic_ProductData> products = new List<ic_ProductData>();
foreach( var product in query)
{
  product.ProductData.RelatedProductDef = product.Def;
  products.Add(product);
}

Basicly, you first need to do the one query to the database, this returns an anonymous type containing both your product and its Def. Finally, you loop (in memory, no db-calls!) over these, creating your final objects with their RelatedProductDef properties populated.

edited Nov 26, 2015 at 13:11

answered Nov 26, 2015 at 13:06

Tom Wuyts

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3 Comments

ViRuSTriNiTy Over a year ago

.ToList() is unnecessary as the statement returns an System.Linq.IQueryable<> which can be used in the foreach loop instead

Tom Wuyts Over a year ago

@ViRuSTriNiTy it is indeed unnecessary, I do find its impact (in performance) to be minimal however.

samar Over a year ago

@Tom Wuyts This seems to be a good solution. Will give it a shot! Will update you on this soon. Up vote from me.

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