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The ORM API, allows you to write complex logic and wizards to provide a rich user interaction for your apps. The ORM provides few methods to programmatically interact with the Odoo data model and the data, called the Application Programming Interface (API). These start with the basic CRUD (create, read, update, delete) operations, but also include other operations, such as data export and import, or utility functions to aid the user interface and experience. It also provides some decorators which allow us, when adding new methods, to let the ORM know how they should be handled.
In this article, we will learn how to use the most important API methods available for any Odoo Model, and the available API decorators to be used in our custom methods, depending on their purpose. We will also explore the API offered by the Discuss app since it provides the message and notification features for Odoo.
ORM decorators are important for the ORM, and allow it to give those methods specific uses.
Let’s see the ORM decorators we have available, and when each should be used.
Most of the time, we want a custom method to perform some actions on a recordset. For this, we should use @api.multi, and in that case, the self argument will be the recordset to work with. The method’s logic will usually include a for loop iterating on it. This is surely the most frequently used decorator.
In some cases, the method is prepared to work with a single record (a singleton). Here we could use the  @api.one decorator, but this is not advised because for Version 9.0 it was announced it would be deprecated and may be removed in the future.
Instead, we should use @api.multi and add to the method code a line with self.ensure_one(), to ensure it is a singleton as expected. Despite being deprecated, the @api.one decorator is still supported. So it’s worth knowing that it wraps the decorated method, doing the for-loop iteration to feed it one record at a time. So, in an @api.one decorated method, self is guaranteed to be a singleton. The return values of each individual method call are aggregated as a list and then returned.
In some cases, the method is expected to work at the class level, and not on particular records. In some object-oriented languages this would be called a static method. These class-level static methods should be decorated with @api.model. In these cases, self should be used as a reference for the model, without expecting it to contain actual records.
A few other decorators have more specific purposes and are to be used together with the decorators described earlier:
When using the preceding decorators, no return value is needed. Except for onchange methods that can optionally return a dict with a warning message to display in the user interface.
As an example, we can use this to perform some automation in the To-Do form: when Responsible is set to an empty value, we will also empty the team list. For this, edit the todo_stage/models/todo_task_model.py file to add the following method:
Here, we are using the @api.onchange decorator to attach some logic to any changes in the user_id field, when done through the user interface. Note that the actual method name is not relevant, but the convention is for its name to begin with onchange_.
Inside an onchange method, self represents a single virtual record containing all the fields currently set in the record being edited, and we can interact with them. Most of the time, this is what we want to do: to automatically fill values in other fields, depending on the value set to the changed field. In this case, we are setting the team_ids field to an empty value.
The onchange methods don’t need to return anything, but they can return a dictionary containing a warning or a domain key:
The decorators discussed in the previous section allow us to add certain features to our models, such as implementing validations and automatic computations.
We also have the basic methods provided by the ORM, used mainly to perform CRUD (create, read, update and delete) operations on our model data. To read data, the main methods provided are search() and browse().
Now we will explore the write operations provided by the ORM, and how they can be extended to support custom logic.
The ORM provides three methods for the three basic write operations:
The values argument is a dictionary, mapping field names to values to write.
In some cases, we need to extend these methods to add some business logic to be triggered whenever these actions are executed. By placing our logic in the appropriate section of the custom method, we can have the code run before or after the main operations are executed.
Using the TodoTask model as an example, we can make a custom create(), which would look like this:
A custom write() would follow this structure:
While extending create() and write()  opens up a lot of possibilities, remember in many cases we don’t need to do that, since there are tools also available that may be better suited:
Consider carefully if you really need to use extensions to the create or write methods. In most cases, we just need to perform some validation or automatically compute some value, when the record is saved. But we have better tools for this: validations are best implemented with @api.constrains methods, and automatic calculations are better implemented as computed fields. In this case, we need to compute field values when saving. If, for some reason, computed fields are not a valid solution, the best approach is to have our logic at the top of the method, accumulating the changes needed into the vals dictionary that will be passed to the final super() call.
For the write() method, having further write operations on the same model will lead to a recursion loop and end with an error when the worker process resources are exhausted. Please consider if this is really needed. If it is, a technique to avoid the recursion loop is to set a flag in the context. For example, we could add code such as the following:
With this technique, our specific logic is guarded by an if statement, and runs only if a specific marker is not found in the context. Furthermore, our self.write() operations should use with_context to set that marker. This combination ensures that the custom login inside the if statement runs only once, and is not triggered on further write() calls, avoiding the infinite loop.
We have seen the most important model methods used to generate recordsets and how to write to them, but there are a few more model methods available for more specific actions, as shown here:
The import and export operations, are also available from the ORM API, through the following methods:
The following methods are mostly used by the web client to render the user interface and perform basic interaction:
Odoo has available global messaging and activity planning features, provided by the Discuss app, with the technical name mail.
The mail module provides the mail.thread abstract class that makes it simple to add the messaging features to any model. To add the mail.thread features to the To-Do tasks, we just need to inherit from it:
After this, among other things, our model will have two new fields available. For each record (sometimes also called a document) we have:
The followers can be either partners or channels. A partner represents a specific person or organization. A channel is not a particular person, and instead represents a subscription list.
Each follower also has a list of message types that they are subscribed to. Only the selected message types will generate notifications for them.
Some types of messages are called subtypes. They are stored in the mail.message.subtype model and accessible in the Technical | Email | Subtypes menu.
By default, we have three message subtypes available:
Subtypes have the default notification settings described previously, but users are able to change them for specific documents, for example, to mute a discussion they are not interested in.
Other than the built-in subtypes, we can also add our own subtypes to customize the notifications for our apps. Subtypes can be generic or intended for a particular model. For the latter case, we should fill in the subtype’s res_model field with the name of the model it should apply to.
Our business logic can make use of this messaging system to send notifications to users. To post a message we use the message_post() method. For example:
This adds a simple text message, but sends no notification to the followers. That is because by default the mail.mt_note subtype is used for the posted messages. But we can have the message posted with the particular subtype we want. To add a message and have it send notifications to the followers, we should use the following:
We can also add a subject line to the message by adding the subject parameter. The message body is HTML, so we can include markup for text effects, such as <b> for bold text or <i> for italics.
Also interesting from a business logic viewpoint is the ability to automatically add followers to a document, so that they can then get the corresponding notifications. For this we have several methods available to add followers:
The default subtypes will be used. To force subscribing a specific list of subtypes, just add the subtype_ids=<list of int IDs> with the specific subtypes you want to be subscribed.
In this article, we went through an explanation of the features the ORM API proposes, and how they can be used when creating our models. We also learned about the mail module and the global messaging features it provides.
To look further into ORM, and have a deeper understanding of how recordsets work and can be manipulated, read our book Odoo 11 Development Essentials – Third Edition.
ERP tool in focus: Odoo 11
Building Your First Odoo Application
How to Scaffold a New module in Odoo 11

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