Made change to allow models to update primary key values

[dhumphreys]

This was a problem in some places where numeric or character IDs needed to be changed, but Wheels was not putting the properties in the SET for the UPDATE to run.

Based on my findings, the hasChanged() call should be a sufficient check to decide whether or not to update any property value. The $addKeyWhereClause() function called from within $update() even considers that primary key values may have been changed. It doesn't make sense to not allow the model to send these changed values to the SQL server if the application required it.

This is reopening pull request #9, which I accidentally closed.

[dhumphreys]

Say you have a model, users, with a primary key of 'username' and an additional 'password' field.
When you run:

user = model("user").findByKey("dhumphreys");
user.update(username="dhumphreys2");

The update will go through without error, but the 'username' primary key is not actually updated. The changed piece of code was keeping any properties that are part of the primary key from ever being updated. In some situations, such as when an auto incremented numeric id is used, this is appropriate. However, there are cases where some applications may need to update primary key values, especially in tables with composite keys. My change allows any property to be updated, as long as it has actually been changed in the model object.

[rip747]

don,

you're part of core now so you can commit this directly. I still think there are some areas with this patch that we need to consider such as security. rails doesn't allow you to update primary keys through direct access or mass assignment. personally i would like to have some sort of setting this feature to be turned on both globally and at the model level.

[dhumphreys]

Yes, I know I can commit directly. I just knew that this issue required some discussion, so I have not merged it yet. I also already had the changes in my own branch and saw no reason to put an extra feature branch in the main wheels repository.

We could enable this with a setting pretty easily. It only really comes into play when not using an auto increment integer as primary key.

[rip747]

looking at this again, i'm still thinking that this can cause quite a bit of havoc and security problems. including this patch would allow any primary key to be updated through mass assignment. the only way around that would be to use protectedProperties() and state the primary keys as protected properties on each model, which would be a pain.

this still leaves the problem though of when you actually need to update a primary key. for that a work around is to use the updateAll() method which doesn't have the restrictions of using update().