The business logic layer

Now we will add some logic to our buttons. This is done with Python code, using the methods in the model's Python class.

Adding business logic

We should edit the todo_model.py Python file to add to the class the methods called by the buttons. First, we need to import the new API, so add it to the import statement at the top of the Python file:

from odoo import models, fields, api 

The action of the Toggle Done button will be very simple: just toggle the Is Done? flag. For logic on records, use the @api.multi decorator. Here, self will represent a recordset, and we should then loop through each record.

Inside the TodoTask class, add this:

@api.multi 
def do_toggle_done(self): 
    for task in self: 
        task.is_done = not task.is_done 
    return True 

The code loops through all the to-do task records and, for each one, modifies the is_done field, inverting its value. The method does not need to return anything, but we should have it to at least return a True value. The reason is that clients can use XML-RPC to call these methods, and this protocol does not support server functions returning just a None value.

For the Clear All Done button, we want to go a little further. It should look for all active records that are done, and make them inactive. Usually form buttons are expected to act only on the selected record, but in this case, we will want it also act on records other than the current one:

@api.model 
def do_clear_done(self): 
    dones = self.search([('is_done', '=', True)]) 
    dones.write({'active': False}) 
    return True 

On methods decorated with @api.model, the self variable represents the model with no record in particular. We will build a dones recordset containing all the tasks that are marked as done. Then, we set the active flag to False on them.

The search method is an API method that returns the records that meet some conditions. These conditions are written in a domain, which is a list of triplets. We'll explore domains in more detail in Chapter 6 , Views - Designing the User Interface.

The write method sets the values at once on all the elements of the recordset. The values to write are described using a dictionary. Using write here is more efficient than iterating through the recordset to assign the value to each of them one by one.

Adding tests

Now we should add tests for the business logic. Ideally, we want every line of code to be covered by at least one test case. In tests/test_todo.py, add a few more lines of code to the test_create() method:

# def test_create(self): 
        # ... 
        # Test Toggle Done 
        task.do_toggle_done() 
        self.assertTrue(task.is_done) 
        # Test Clear Done 
        Todo.do_clear_done() 
        self.assertFalse(task.active)

If we now run the tests and the model methods are correctly written, we should see no error messages in the server log:

$ ./odoo-bin -d todo -i todo_app --test-enable