plone.directives.form 1.0b4

Schemata loaded from XML

If you want to create a concrete interface, with a real module path, from a plone.supermodel XML file, you can do:

from plone.directives import form
class IMySchema(form.Schema):
    form.model('myschema.xml')

The file will be loaded from the directory where the .py file for the interface is located, unless an absolute path is given.

If the interface contains additional schema fields, they will add to and override fields defined in the XML file.

See tests/schema.txt for more details.

Form widget hints

The plone.autoform package provides the ability to generate a form from a schema, using hints stored in tagged values on that schema to control form’s layout and field widgets. Those hints can be set using directives in this package.

Below is an example that exercises the various directives:

from plone.directives import form
from plone.app.z3cform.wysiwyg import WysiwygFieldWidget

class IMySchema(form.Schema):

    # Add a new fieldset and put the 'footer' and 'dummy' fields in it.
    # If the same fieldset is defined multiple times, the definitions
    # will be merged, with the label from the first fieldset taking
    # precedence.

    form.fieldset('extra',
            label=u"Extra info",
            fields=['footer', 'dummy']
        )

    title = schema.TextLine(
            title=u"Title"
        )

    summary = schema.Text(
            title=u"Summary",
            description=u"Summary of the body",
            readonly=True
        )

    form.widget(body='plone.app.z3cform.wysiwyg.WysiwygFieldWidget')
    body = schema.Text(
            title=u"Body text",
            required=False,
            default=u"Body text goes here"
        )


    form.widget(footer=WysiwygFieldWidget)
    footer = schema.Text(
            title=u"Footer text",
            required=False
        )

    form.omitted('dummy')
    dummy = schema.Text(
            title=u"Dummy"
        )

    form.mode(secret='hidden')
    secret = schema.TextLine(
            title=u"Secret",
            default=u"Secret stuff"
        )

    form.order_before(not_last='summary')
    not_last = schema.TextLine(
            title=u"Not last",
        )

Here, we have placed the directives immediately before the fields they affect, but they could be placed anywhere in the interface body. All the directives can take multiple values, usually in the form fieldname=’value’. The ‘omitted()’ directive takes a list of omitted field names instead. The ‘widget()’ directive allows widgets to be set either as a dotted name, or using an imported field widget factory. The ‘order_before()’ directive has a corresponding ‘order_after()’ directive.

Value adapters

z3c.form has the concept of a ‘value adapter’, a component that can provide a value for an attribute (usually of widgets and buttons) at runtime. This package comes with some helpful decorators to register value adapters for computed values. For example:

from plone.directives import form
from zope import schema

class IMySchema(form.Schema):

    title = schema.TextLine(title=u"Title")

@form.default_value(field=IMySchema['title'])
def default_title(data):
    return data.context.suggested_title

The decorator takes one or more discriminators. The available descriminators for default_value are:

context

The type of context (e.g. an interface)

request

The type of request (e.g. a layer marker interface). You can use ‘layer’ as an alias for ‘request’, but note that the data passed to the function will have a ‘request’ attribute only.

view

The type of form (e.g. a form instance or interface). You can use ‘form’ as an alias for ‘view’, but note that the data passed to the function will have ‘view’ attribute only.

field

The field instance (or a field interface).

widget

The widget type (e.g. an interface).

You must specify either ‘field’ or ‘widget’. The object passed to the decorated function has an attribute for each descriminator.

There are two more decorators:

widget_label

Provide a dynamic label for a widget. Takes the same discriminators as the default_value decorator.

button_label – Provide a dynamic label for a button. Takes parameters

content (alias context), request (alias layer), form (alias view), manager and button.

Please note the rather unfortunate differences in naming between the button descriptors (content vs. context, form vs. view) and the widget ones. The descriptor will accept the same names, but the data object passed to the function will only contain the names as defined in z3c.form, so be careful.

Form base classes

If you need to create your own forms, this package provides a number of convenient base classes that will be grokked much like a grok.View or grok.CodeView. The grokkers take care of wrapping the form in a plone.z3cform FormWrapper as well.

The base classes can all be imported from plone.directives.form, e.g:

from plone.directives import form
from z3c.form import field

class MyForm(form.Form):
    fields = field.Fields(IMyFormSchema)
    ...

The various options are:

Form

A simple page form, basically a grokked and automatically wrapped version of z3c.form.form.Form.

SchemaForm

A page form that uses plone.autoform. You must set the ‘schema’ class variable (or implement it as a property) to a schema interface form which the form will be built. Form widget hints will be taken into account.

AddForm

A simple add form with “Add” and “Cancel” buttons. You must implement the create() and add() methods. See the z3c.form documentation for more details.

SchemaAddForm

An add form using plone.autoform. Again, you must set the ‘schema’ class variable.

EditForm

A simple edit form with “Save” and “Cancel” buttons. See the z3c.form documentation for more details.

SchemaEditForm

An edit form using plone.autoform. Again, you must set the ‘schema’ class variable.

DisplayForm

A view with an automatically associated template (like grok.View), that is initialised with display widgets. See plone.autoform’s WidgetsView for more details.

1.0a2 - 2009-07-12

• Made adjustments for changes in plone.supermodel’s API. [optilude]

1.0b2 - 2009-06-15

• Make sure that we don’t lose the function when using the @form.default_value() decorator and the other value decorators. [optilude]

1.0b1 - 2009-04-17

• Initial release