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Model Constraints & Python
Constraints in Odoo 15
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2.
INTRODUCTION
 Odoo helps you to set constraints to variants which we can perform using python and
model constraints. In odoo python constraints are specified along with methods.
 This Slide will provide an insight on python and model constraints in Odoo 15.
 In python, constraints are defined along with a method decorated with constraints().

3.
Python Constraints
Add a constraint while saving a record you can use the following code which restricts the user from entering a
negative value for the amount.

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 The field for which constraint is to be applied is specified along with the decorator constraints().
 provide multiple field values as arguments in the function. Therefore, the function gets invoked
each time the value in the field gets modified/changed

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@api.constrains(field1, field2)
def _check_values(self):
for record in self:
if record.field1 == record.field2:
raise ValidationError("Fields field1 and field2 must be not be same")
Example code

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There are certain limitations for using constraints()
1. constrains() are not supported along with related fields. They can only be applied to simple fields. For
example related fields like partner_id.phone.
2. constrains() can only be applied to fields that are included in the create and write call because if the
field is which is not contained in the view will not trigger a call to python function.

7.
SQL constraints
 The SQL constraints are applied on models using _sql_constraints.
 In odoo _sql_constraints consist of three parts they are name, definition, and message.

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 name - Name for the sql constraint
 definition - Constraint to be applied on the table.
 message - Validation message to be displayed.

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Unique Constraint:
It is used along with a ‘unique’ keyword.
The unique constraint helps you to check whether a specified column in rows
satisfies the unique constraint.

10.
For More
Details
Check our company website for related blogs and Odoo
book.
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videos in Odoo.
Model Constraints & Python Constraints in Odoo15

11.
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