CODEWITHSUNDEEP
c#.netsqlsql-serverlinq-to-sql
MakkyNZ
MakkyNZ

Reputation: 2255

Linq to SQL SubmitChanges only for specific table

I have been using linq to sql for a little while and often come up against this type of problem....

e.g I have 2 db tables

-Table: Invoice ("Id" int auto-increment, "InvoiceDate" datetime)

-Table: InvoiceItems ("Id" int auto-increment, "InvoiceId" int (FK), "SomeReference" varchar(50))

The "SomeReference" field holds a value that is a combination of the Id from the parent Invoice record and some random characters. eg. "145AHTL"

Before i can set the value of SomeReference I need to know the value of the Invoice Id, but this only gets populated when it is saved to the DB. I have both parent and child records in the same Linq to SQl DB Context but I only want to perform "SubmitChanges" to the parent Invoice record only, so that i can then populate the SomeReference in the child record. I dont want to have the child InvoiceItem record saved to the DB before SomeReference is set.

How can I achieve this using Linq to Sql?

I understand that linq to sql uses the "Unit of Work" idea for saving to db, but I dont understand how I can avoid unnecessarily saving records to the db when they are not ready to be saved just yet. If there is no way around this, then why do developers bother with linq to sql, as this seems like such a huge drawback?

edit: should note that this example is just something i came up with to help describe my problem.

Upvotes: 1

Views: 1341

Answers (2)

Pleun
Pleun

Reputation: 8920

You example can be done, but you need to forget about the SQL and the database, but think in an ORM way.

Two issues need to be addressed in your example

First inserting the master and detail at the same time

Pseudo code for how it works:

using (var dc = new datacontext())

var master = new masterentity;
master.somedata = "data";
dc.tb_master.InsertOnSumbut(master)
var detail = new detailentity
detail.tb_master = master
dc.tb_detail.InsertOnSubmit(detail)
Submitchanges()

So you assign the entities to eachother, not the keys.

Second: the SomeReference

This first part however, does not give you the somereference field, only sets the the foreign key properly.

Your somereference field contains redundant data (not necessary) so that needs to be solved.

The somereference is a string + the ID.

So you store the string part in a column in the database (and only that) and you implement a custom property somereference by using a partial class.

  public partial class tb_detail
    {
        public string somereference
        {
             get
            {
               return _id.ToString() + _somestring;
}}}

Upvotes: 1

TomTom
TomTom

Reputation: 62129

You can not. Not this way. And this is the only way (linq dues not support sequences). Brutally speaking - you have to fix your logic. The Id of an invoice is not a refernce field. It should not ever never be the number. This is a logical field and should be handled by your logic, outside the Id.

Upvotes: 1

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