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Various utilities for XBlocks

Project description

xblock-utils: Various utilities for XBlocks

These are a collection of useful utility functions,
test base classes and documentation shared by many XBlocks.
(Especially those of `edx-solutions`_.)

.. _edx-solutions:

To test the utilities, run::


To get a coverage report, use:

python --with-coverage --cover-package=xblockutils --cover-html


.. code:: python

from xblockutils.studio_editable import StudioEditableXBlockMixin

This mixin will automatically generate a working ``studio_view`` form
that allows content authors to edit the fields of your XBlock. To use,
simply add the class to your base class list, and add a new class field
called ``editable_fields``, set to a tuple of the names of the fields
you want your user to be able to edit.

.. code:: python

class ExampleBlock(StudioEditableXBlockMixin, XBlock):
mode = String(
help="Determines the behaviour of this component. Standard is recommended.",
values=('standard', 'crazy')
editable_fields = ('mode', 'display_name')

That's all you need to do. The mixin will read the optional
``display_name``, ``help``, ``default``, and ``values`` settings from
the fields you mention and build the editor form as well as an AJAX save

If you want to validate the data, you can override
``validate_field_data(self, validation, data)`` and/or
``clean_studio_edits(self, data)`` - see the source code for details.

Supported field types:

* Boolean:
``field_name = Boolean(display_name="Field Name")``
* Float:
``field_name = Float(display_name="Field Name")``
* Integer:
``field_name = Integer(display_name="Field Name")``
* String:
``field_name = String(display_name="Field Name")``
* String (multiline):
``field_name = String(multiline_editor=True, resettable_editor=False)``
* String (html):
``field_name = String(multiline_editor='html', resettable_editor=False)``

Any of the above will use a dropdown menu if they have a pre-defined
list of possible values.

* List of unordered unique values (i.e. sets) drawn from a small set of
possible values:
``field_name = List(list_style='set', list_values_provider=some_method)``

- The ``List`` declaration must include the property ``list_style='set'`` to
indicate that the ``List`` field is being used with set semantics.
- The ``List`` declaration must also define a ``list_values_provider`` method
which will be called with the block as its only parameter and which must
return a list of possible values.
* Rudimentary support for Dict, ordered List, and any other JSONField-derived field types

- ``list_field = List(display_name="Ordered List", default=[])``
- ``dict_field = Dict(display_name="Normal Dict", default={})``

Supported field options (all field types):

* ``values`` can define a list of possible options, changing the UI element
to a select box. Values can be set to any of the formats `defined in the
XBlock source code <>`__:

- A finite set of elements: ``[1, 2, 3]``
- A finite set of elements where the display names differ from the values
{"display_name": "Always", "value": "always"},
{"display_name": "Past Due", "value": "past_due"},
- A range for floating point numbers with specific increments:
``{"min": 0 , "max": 10, "step": .1}``
- A callable that returns one of the above. (Note: the callable does
*not* get passed the XBlock instance or runtime, so it cannot be a
normal member function)
* ``values_provider`` can define a callable that accepts the XBlock
instance as an argument, and returns a list of possible values in one
of the formats listed above.
* ``resettable_editor`` - defaults to ``True``. Set ``False`` to hide the
"Reset" button used to return a field to its default value by removing
the field's value from the XBlock instance.

Basic screenshot: |Screenshot 1|


.. code:: python

from xblockutils.studio_editable import StudioContainerXBlockMixin

This mixin helps to create XBlocks that allow content authors to add,
remove, or reorder child blocks. By removing any existing
``author_view`` and adding this mixin, you'll get editable,
re-orderable, and deletable child support in Studio. To enable authors to
add arbitrary blocks as children, simply override ``author_edit_view``
and set ``can_add=True`` when calling ``render_children`` - see the
source code. To restrict authors so they can add only specific types of
child blocks or a limited number of children requires custom HTML.

An example is the mentoring XBlock: |Screenshot 2|


.. code:: python

from xblockutils.base_test import SeleniumXBlockTest

This is a base class that you can use for writing Selenium integration
tests that are hosted in the XBlock SDK (Workbench).

Here is an example:

.. code:: python

class TestStudentView(SeleniumXBlockTest):
Test the Student View of MyCoolXBlock
def setUp(self):
super(TestStudentView, self).setUp()
self.set_scenario_xml('<mycoolblock display_name="Test Demo Block" field2="hello" />')
self.element = self.go_to_view("student_view")

def test_shows_field_2(self):
The xblock should display the text value of field2.
self.assertIn("hello", self.element.text)


.. code:: python

from xblockutils.studio_editable_test import StudioEditableBaseTest

This is a subclass of ``SeleniumXBlockTest`` that adds a few helper
methods useful for testing the ``studio_view`` of any XBlock using


.. code:: python

from xblockutils.helpers import child_isinstance

If your XBlock needs to find children/descendants of a particular
class/mixin, you should use

.. code:: python

child_isinstance(self, child_usage_id, SomeXBlockClassOrMixin)

rather than calling

.. code:: python

``isinstance(self.runtime.get_block(child_usage_id), SomeXBlockClassOrMixin)``.

On runtimes such as those in edx-platform, ``child_isinstance`` is
orders of magnitude faster.

.. |Screenshot 1| image::
.. |Screenshot 2| image::


This mixin provides access to instance-wide XBlock-specific configuration settings.
See [wiki page]( for details


This mixin provides XBlock theming capabilities built on top of XBlock-specific settings.
See [wiki page]( for details

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