overriding breeze BeforeSaveEntity()

Question

I was having the exact same problem as discussed in breezejs issues with the save bundle and the answer explains it great.

The problem I have is - my application is somewhat large, having about 20+ entities that we modify. Hence if I override the BeforeSaveEntity() within my datacontext and add all the business logic there it would be very cumbersome. We do have a clear separation of concerns as I have mentioned in the following question (mind the half-completed title): Is it a good practice to use multuple

So is there anyway I can do this in a more organized manner? I mean handling the BeforeSaveEntity for related entities in one single repository and likewise?

Answer 1

Of course you can branch inside your BeforeSaveEntities method, as shown in the code of the answer you linked to above. Inside each if block, you could instantiate a helper class or repository to handle each entity type.

A more domain-based approach would be to have multiple subclasses of EFContextProvider<MyDbContext>. Each one would have its own BeforeSaveEntities method to handle its own domain business rules:

public class AccountManagementContextProvider : EFContextProvider<MyDbContext>
{
    Type[] allowedTypes = new Type[] { typeof(Account), typeof(AccountAddress) };

    protected override Dictionary<Type, List<EntityInfo>> BeforeSaveEntities(Dictionary<Type, List<EntityInfo>> saveMap)
    {
        var illegalTypes = saveMap.Keys.Except(allowedTypes);
        if (illegalTypes.Any())
        {
            throw new ArgumentException("Attempt to save illegal entities");
        }

        // account management stuff...
    }
}

// in a separate file...
public class InventoryContextProvider : EFContextProvider<MyDbContext>
{
    protected override Dictionary<Type, List<EntityInfo>> BeforeSaveEntities(Dictionary<Type, List<EntityInfo>> saveMap)
    {
        // inventory stuff...
    }
}        
// etc.

You can instantiate the appropriate ContextProvider instance in your controller methods:

[HttpPost]
public SaveResult SaveAccount(JObject saveBundle)
{
    var context = new AccountManagementContextProvider();
    return context.SaveChanges(saveBundle);
}

[HttpPost]
public SaveResult SaveInventory(JObject saveBundle)
{
    var context = new InventoryContextProvider();
    return context.SaveChanges(saveBundle);
}

... which you call from the client using named saves:

    var saveOptions = new breeze.SaveOptions({ resourceName: 'SaveInventory' });
    return manager.saveChanges(null, saveOptions);