Linq to SQL删除/添加子对象

Question

I have a customer table which has a child table called customer addresses.

Customer:

CustomerID
Name
IsActive

CustomerAddresses:

CustomerAddressID
CustomerID
Street
City
State
ZipCode

I would like to update the customer table with a list of customer addresses and have it automatically remove/add the entries if they already exist.

Does linq to SQL do this automatically or does it have to be done manually.

Answer 1

You have to synchronize manually.

I'm not sure this is the best method. But it's an option:

var preExistentIds = (from x in context.CustomerAddresses select x.CustomerAddressID).ToList();

foreach (var deleted in preExistentIds.Where(x => !newCustomerAddr.Exists(y => y.CustomerAddressID == x)))
{
    var entity = new CustomerAddresses { CustomerAddressID = deleted.CustomerAddressID };
    context.CustomerAddresses.Attach(entity);
    context.Entry(entity).State = EntityState.Deleted;
}

foreach(var item in newCustomerAddr){
    var entity = new CustomerAddresses { CustomerAddressID = item.CustomerAddressID };
    context.CustomerAddresses.Attach(entity);
    entity.Fields = item.Field;
    [..]
    context.Entry(entity).State = item.CustomerAddressID == 0? EntityState.Added : EntityState.Modified;
}

db.SaveChanges();