Nuts and Bolts

The Ambidexterity editor is a UI for a mechanism that provides a custom browser view @@ambidexterityview and a Dexterity defaultFactory collective.ambidexterity.default, a form:validator collective.ambidexterity.validate, and a vocabulary source collective.ambidexterity.vocabulary.

Each of these knows how to do two tricks when called:

• It introspects the calling environment to deduce the content type and field type; and
• It uses that knowledge to find a matching script or template in portal_resources.

Templates are rendered as usual. Scripts are interpreted in RestrictedPython and each has special globals. After script execution, the script’s local variables are examined to get results.

Ambidexterity views work for all content types. Scripts work only for through-the-web content types where the supermodel XML version of the schema is a property of the factory type information (FTI).

The general idea is that we use Dexterity XML to specify a schema like:

<schema>
  <field name="test_integer_field" type="zope.schema.Int">
    <description/>
    <required>False</required>
    <defaultFactory>collective.ambidexterity.default</defaultFactory>
    <title>Test Integer Field</title>
  </field>
  <field name="test_string_field"
    type="zope.schema.TextLine"
    form:validator="collective.ambidexterity.validate"
  >
    <description/>
    <required>False</required>
    <defaultFactory>collective.ambidexterity.default</defaultFactory>
    <title>Test String Field</title>
  </field>
  <field name="test_choice_field" type="zope.schema.Choice">
    <description/>
    <required>False</required>
    <title>Test Choice Field</title>
    <source>collective.ambidexterity.vocabulary</source>
  </field>
</schema>

For the Dexterity type “my_simple_type” and we would get:

portal_resources/ambidexterity/my_simple_type/test_integer_field/default.py
portal_resources/ambidexterity/my_simple_type/test_string_field/default.py
portal_resources/ambidexterity/my_simple_type/test_string_field/validate.py
portal_resources/ambidexterity/my_simple_type/test_choice_field/vocabulary.py

automatically called as appropriate.

Defaults

The script is given one value (other than standard builtins): “context” – which is either the creation folder if the item is being added or the item if being edited.

The default value should be assigned to “default” in the script and should be of the type required by the field.

Vocabularies

The script is given one value (other than standard builtins): “context” – which is either the creation folder if the item is being added or the item if being edited.

The vocabulary should be assigned to “vocabulary” in the script. It should be a list of values or a list of items (value, title).

Validators

The script is given two values (other than standard builtins):

• “context” – which is either the creation folder if the item is being added or the item if being edited.
• “value” – the field value submitted for validation.

If the validator script determines the value is invalid, it should assign an error message to a variable named “error_message”.

If the value is valid, do not do either of the above. The absence of an error message is taken to mean all is OK.

Views

If a view.pt template file is placed at portal_resources/ambidexterity/content_type/view.pt as a text file, it will be usable at @@ambidexterityview.

You may also set other template files and traverse to them at URLs like @@ambidexterityview/custom_file.js. No matter the extension, they will be handled as page templates.