7_relations.md

Relations Between Models

A record from a model may be related to a record from another model. Relational fields link records, either of the same model (hierarchies) or between different models. Here 3 types of Relations are introduced below.

1. Many2one

• In our appointment.py file, an appointment have a connection to a patient. The value of this field is a record of a model that is associated with kmhospital.patient. For this we have to add Many2one fields to the models and add them in the views.

• Remember: By convention, Many2one fields have the _id suffix.

  patient_id = fields.Many2one("kmhospital.patient", string='Patient Name', required=True)

  Checkout the code snippet

• Add that field to the tree and form view in the appointment_view.xml.

  <field name="patient_id"/>

  Checkout the code snippet

  

* Related fields

• After selecting the patient name, the patient age, gender, phone and email will automatically be updated for the patient by using the related field.

  phone = fields.Char(string='Phone', related='patient_id.phone')
  email = fields.Char(string='Email', related='patient_id.email')
  age = fields.Integer(string='Age', related='patient_id.age')

  Here patient_id is the Many2one field and it will come from kmhospital.patient model.

  

  • Check out the code

2. Many2many

It is bidirectional multiple relationship field, any record on one side can be related to any number of records on the other side.

• In appointment.py file, Many2many is used to add the multiple medical test. By convention, Many2many fields have the _ids suffix.

  prescription_medical_test_ids = fields.Many2many("kmhospital.medicaltest", "medical_test_ids", string="Medical tests")

  Checkout the code snippet

• We also have to add another Many2many field for the medical test in medicaltest.py.

  medical_test_ids = fields.Many2many(string="Medical tests")

  Checkout the code snippet

• Add the field in the views file appointment_view.xml in tree and from view.

  <field name="prescription_medical_test_ids"/>

  Checkout the code snippet

  

3. One2many

• In appointment.py file, One2many is used to store multiple records of medicine. By convention, One2many fields have the _ids suffix.

  prescription_medicine_ids = fields.One2many("kmhospital.appointment.prescription.medicine", "appointment_medicine_id", string="Prescription Medicine")

  Checkout the code snippet

• As One2many is a virtual relationship, there must be a Many2one field in the other model, in our case the model is kmhospital.appointment.prescription.medicine, and the field name must be related field like appointment_medicine_id.

  appointment_medicine_id = fields.Many2one("kmhospital.appointment", string="Appointment medicine")

  Checkout the code snippet

• Add the view to the appointment_view.xml.

  <field name="prescription_medicine_ids"/>

• As this field is an editable field we have to change it with tree and from view.

  <field name="prescription_medicine_ids">
      <tree editable="bottom">
          <field name="name"/>
          <field name="quantity"/>
      </tree>
      <form>
          <group>
              <group>
                  <field name="name"/>
              </group>
              <group>
                  <field name="quantity"/>
              </group>
          </group>
      </form>
  </field>

  Checkout the code snippet

  

🚀 Happy Coding ! 🔥