Domains represent a set of records. A domain is a list of none or more clauses. A clause is a condition, which returns true or false. A record belongs to a domain, when the final result of the list of clauses returns true.
The definition of a simple domain with one clause is represented by this pattern:
domain = [(<field name>, <operator>, <operand>)]
Is the name of a trytond.model.fields or a pyson statement, that evaluates to a string.
A field of type trytond.model.fields.Many2One can be dereferenced to related models. This is illustrated by the following example:
domain = [('country.name', '=', 'Japan')]
The number of dots in a clause is not limited.
The definition of an empty domain is:
domain = []
An empty domain without clauses will always return all active records. A record is active, when its appropriate Model contains a Boolean field with name active, and set to true. When the appropriate Model does not contain a Boolean field with name active all records are returned.
A domain can be setup as a combination of clauses, like shown in this pattern:
domain = [
('field name1', 'operator1', 'operand1'),
('field name2', 'operator2', 'operand2'),
('field name3', 'operator3', 'operand3'),]
The single clauses are implicitly combined with a logical AND operation.
In the domain syntax it is possible to provide explicitly the combination operation of the clauses. These operations can be AND or OR. This is illustrated by the following pattern:
domain = [ 'OR', [
('field name1', 'operator1', 'operand1'),
('field name2', 'operator2', 'operand2'),
], [
('field name3', 'operator3', 'operand3'),
],]
Here the domain is evaluated like this: ((clause1 AND clause2) OR clause3). Please note that the AND operation is implicit assumed when no operator is given. While the OR operation must be given explicitly. The former pattern is equivalent to the following completely explicit domain definition:
domain = [ 'OR',
[ 'AND', [
('field name1', 'operator1', 'operand1'),
], [
('field name2', 'operator2', 'operand2'),
],
], [
('field name3', 'operator3', 'operand3'),
],]
Obviously the use of the implicit AND operation makes the code more readable.
The following operators are allowed in the domain syntax. <field name>, <operator> and <operand> are dereferenced to their values. The description of each operator follows this pattern, unless otherwise noted:
(<field name>, <operator>, <operand>)
Is a parity operator. Returns true when <field name> equals to <operand>.
Is a pattern matching operator. Returns true when <field name> is contained in the pattern represented by <operand>.
In <operand> an underscore (_) matches any single character, a percent sign (%) matches any string with zero or more characters. To use _ or % as literal, use the backslash \ to escape them. All matching is case sensitive.
Is a pattern matching operator. The same use as like operator, but matching is case insensitive.
Is a list member operator. Returns true when <field name> is in <operand> list.
Is a less than operator. Returns true for type string of <field name> when <field name> is alphabetically sorted before <operand>.
Returns true for type number of <field name> when <field name> is less than <operand>.
Is a greater than operator. Returns true for type string of <field name> when <field name> is alphabetically sorted after <operand>.
Returns true for type number of <field name> when <field name> is greater <operand>.
Is a less than or equal operator. Returns the same as using the < operator, but also returns true when <field name> is equal to <operand>.
Is a greater than or equal operator. Returns the same as using the > operator, but also returns true when <field name> is equal to <operand>.
Is a parent child comparison operator. In case <field name> is a one2many returns true, if <field name> is a child of <operand>. <field name> and <operand> are represented each by an id. In case <field name> is a many2many not linked to itself, the clause pattern extends to:
(<field name>, ['child_of'|'not_child_of'], <operand>, <parent field>)Where <parent field> is the name of the field constituting the many2one on the target model.