predicates.md

Using predicates

Predicates are conditional expressions that return a boolean on evaluation. Commonly written as $leftOperand $comparisonOperator $rightOperand for example: true !== false

Predicates are used by the following clauses: filter, prune and search; as well as functions such as: analyzer and boost.

Singular predicates

You can use the following syntax' to build predicates:

Basic:

$leftOperand, $comparisonOperator, $rightOperand

Example: find active users

$qb->for('u', 'users')->filter('u.active', '==', true)->return('u'); 

resolves to :

FOR u IN users FILTER u.active == true RETURN u 

without the rightOperand

When you exclude the rightOperand a null value will be assumed. $leftOperand, $comparisonOperator resolves to $leftOperand $comparisonOperator null

Example: find users that don't have their age set.

$qb->for('u', 'users')->filter('u.age', '==')->return('u'); 

resolves to :

FOR u IN users FILTER u.active == null RETURN u 

leftOperand only

When just supplying the leftOperand the operator and rightOperand will be left blank. This useful to resolve the result of a function or subquery.

Note that other values such as arrays or scalars always resolve to tru Example: find users that have their age set.

$qb->for('u', 'users')->filter('u.age')->return('u'); 

resolves to :

FOR u IN users FILTER u.active RETURN u 

Predicate groups

You can combine multiple predicates by grouping them in arrays. Example: get users whose age is between 17 and 68.

$qb->for('u', 'users')
    ->filter([
        ['u.age', '>=', 18],
        ['u.age', '<=', 67]
    ])
    ->return('u');

resolves to :

FOR u IN users FILTER u.age >= 18 AND u.age <= 67 RETURN u 

Note: predicate group detect is quite simplistic. A leftOperand that is an array is assumed to be a predicate instead. If you need to use an array in the leftOperand positon use a PredicateExpression

use LaravelFreelancerNL\FluentAQL\Expressions\PredicateExpression;

// ...

$qb->FILTER([
        new PredicateExpression([1, 3, 4], 'ANY IN', [ 4, 5, 6 ]),
        [false, '!==', true]
    ]);

resolves to :

FILTER [1, 3, 4] ANY IN [ 4, 5, 6 ] AND false !== true  

Changing the logical operator between groups:

You can specify a logicalOperator for a predicate which will define its relation to the preceding predicate.

In the previous example the predicates where combined with an 'AND' logical operator. By adding an 'OR' operator to the second predicate you change this default.

Example: get users whose age is not between 17 and 68.

$qb->for('u', 'users')
    ->filter([
        ['u.age', '<=', 18],
        ['u.age', '>=', 67, 'OR']
    ])
    ->return('u');

resolves to :

FOR u IN users FILTER u.age <= 18 OR u.age >= 67 RETURN u