custom_constraints.md

Custom constraints

So you probably have a few custom constraints with you application and you want to use them on the client-side.

For this you will need to do a few things:

• Create a constraint mapper
• Add you constraint mapper to the DI
• Implement the constraint as a jquery validate rule

The goal of a constraint mapper is to map a constraint as a jquery validation rule. In general all constraints are mapped and registered as constraint mappers. So look the constraint mappers available (under src/Form/Rule/Mapping) within the project and create your own.

Once you have create your custom constraint mapper you need to register it in the DI/Service Container. A example is:

acme.form.rule.my_mapper:
    class: Acme\Form\Rule\MyRule
    tags:
     - { name: form_rule_constraint_mapper }

After this you need to make sure you include your jquery validate rule into the page.

DataTransformer Rules/Constraints

In some cases you maybe using a custom 'DataTransformer' that validates your data (or throw a exception when it's invalid). If this is the case you (probably) need to implement a FormRuleProcessor to add a TransformerRule. A good example is src/Form/Rule/Processor/DateTimeToArrayTransformerPass.