实体框架多对多关系。 产品的库存在仓库里

Question

So right now i'm coding a product selection tool for a sales module and i want to show the stock of each product selected for the sale. I have two tables: Products and Warehouses and a table that has a relation between them and the stock of a product in a warehouse.

A query for this would be something along the lines of

productsXwarehouses pxw = dbGateway.productsXwarehouses
.Where(item => item.idproduct=idproduct && item.idWarehouse==idWarehouse).First();

But i would have to do this for each row of the table and it seems really inneficient. I was wondering if maybe there is a better aproach. Thanks!

Thanks!

Answer 1

Try this:

var stock = 
    from pw in dbGateway.productsXwarehouses
    group pw.Product by pw into g
    select new 
    {
        Product = g.Key, 
        TotalStock = g.Sum(w => w.Stock)
    };

I'm assuming that your productsXwarehouses table has a Stock column of type int .

But perhaps an even nicer solution is this:

var stock =
    from product in dbGateway.Products
    select new
    {
        Product = product,
        TotalStock = product.productsXwarehouses.Sum(w => w.Stock)
    };