Entity Framework Insert Update Related Tables Intermediate Table.

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I have a Database first EF model with simple POCO entities.

I receive a new Product or collection of Products and want to do the following
1: Add the new Products to the products table ( seems simple enough to do this in EF from what I read).
2: Add the newly received Products to the Intermediary Table BatchProduct where Batch.ID = BatchProduct.BatchID
2A: If the BatchProduct.BatchID does not exist I want to create it and add my Products to the table.

Is the way my code is written in Example 1 the right way to do this ?

Or should I be setting the product ID's and Batch ID's by themselves ..? and leaving BatchProduct.Batch and BatchProduct.Product alone. As in the Example 2 at the bottom

Example 1:

C#

class Batch
{
  ID {get; set;} // auto-increment in database
  NUMBER {get; set;}
  NAME {get; set;}
}


class PRODUCT
{
  ID {get; set;} // auto-increment in database
  timestamp {get; set;}
  unit {get; set;}

}

class BatchProduct
{
  ID {get; set;}
  BATCHID {get; set;} //[FK in DB]
  PRODUCTID {get; set;} //[FK in DB]

}

using (var db = myDBContext)
{
	BATCH batch = db.BATCHes.SingleOrDefault(b => b.BatchNumber == handshake.Batch);
				
    foreach (PRODUCT product in products) 
    {
	BATCH_PRODUCT batchproduct = new BATCH_PRODUCT();
        db.PRODUCTs.Add(product);
	batchproduct.BATCH = batch;
	batchproduct.PRODUCT = product;
	db.BATCH_PRODUCT.Add(batchproduct);				 
    }
	db.SaveChanges();

}

Example 2:

C#

foreach (PRODUCT product in products) 
{
    BATCH_PRODUCT batchproduct = new BATCH_PRODUCT();
    batchproduct.PRODUCTID = db.PRODUCTs.Add(product).ID;
    batchproduct.BATCHID = batch.ID;
    db.BATCH_PRODUCT.Add(batchproduct);
}
				
db.SaveChanges();

Posted 29-Jul-15 8:58am

stixoffire

Updated 29-Jul-15 9:10am

v3

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Mr Ellipse · Accepted Answer · 2015-07-29T19:19:00

When possible, try to link objects in EF to each other by setting Navigation properties. After all, EF is an Object Relationship Mapper :)

In order to check if a 'related' entity exists already in the database context (to maintain relationship integrity), you are going to have to do some sort of lookup. Use the objects!

This approach works fine for a few hundred objects at a time - but remember EF isn't designed for high volume updates/inserts. If you need maximum throughput, drop back to using underlying ADO.Net classes such as SqlDataReaders or SQLBulkCopy etc.

Below demonstrates how I would approach the situation.

C#

using (var db = myDbContext)
            {
                var batch = db.Batches.SingleOrDefault(b => b.BatchNumber == handShake.Batch);

                if (batch == null)
                {
                    batch = new Batch()
                    {
                        // set new Batch properties
                    };
                }

                foreach (Product product in products)
                {
                    BatchProduct batchproduct = new BatchProduct()
                    {
                        Batch = batch
                    };

                    var existingProduct = db.Products.SingleOrDefault(p => p.ID == product.ID);
                    if (existingProduct != null)
                    {
                        batchproduct.Product = existingProduct;
                    }
                    else
                    {
                        batchproduct.Product = new Product()
                        {
                            // set new Product properties
                        };
                    }
                    db.BatchProducts.Add(batchproduct);
                }
                db.SaveChanges();
            }