============== Source Widgets ============== Sources are objects that represent sets of values from which one might choose and are used with Choice schema fields. Source widgets currently fall into two categories: - widgets for iterable sources - widgets for queryable sources Sources (combined with the available adapters) may support both approaches, but no widgets currently support both. In both cases, the widgets need views that can be used to get tokens to represent source values in forms, as well as textual representations of values. We use the `zope.browser.interfaces.ITerms` views for that. All of our examples will be using the component architecture:: >>> import zope.interface >>> import zope.component >>> import zope.schema This `ITerms` implementation can be used for the sources involved in our tests:: >>> from zope.browser.interfaces import ITerms >>> import zope.publisher.interfaces.browser >>> from zope.schema.vocabulary import SimpleTerm >>> class ListTerms: ... ... zope.interface.implements(ITerms) ... ... def __init__(self, source, request): ... pass # We don't actually need the source or the request :) ... ... def getTerm(self, value): ... title = unicode(value) ... try: ... token = title.encode('base64').strip() ... except binascii.Error: ... raise LookupError(token) ... return SimpleTerm(value, token=token, title=title) ... ... def getValue(self, token): ... return token.decode('base64') This view just uses the unicode representations of values as titles and the base-64 encoding of the titles as tokens. This is a very simple strategy that's only approriate when the values have short and unique unicode representations. All of the source widgets are in a single module:: >>> import zope.formlib.source We'll also need request objects:: >>> from zope.publisher.browser import TestRequest Iterable Source Widgets ======================= Iterable sources are expected to be simpler than queriable sources, so they represent a good place to start. The most important aspect of iterable sources for widgets is that it's actually possible to enumerate all the values from the source. This allows each possible value to be listed in a Since the field is required, an empty selection is not valid: >>> widget.getInputValue() Traceback (most recent call last): MissingInputError: ('field.dog', u'Dogs', None) Also, the widget is required in this case: >>> widget.required True If the request contains a value, it is marked as selected:: >>> request.form["field.dog-empty-marker"] = "1" >>> request.form["field.dog"] = "Ym93c2Vy" >>> print widget()
If we set the displayed value for the widget, that value is marked as selected:: >>> widget.setRenderedValue("duchess") >>> print widget()
Dropdown widgets are achieved with SourceDropdownWidget, which simply generates a selection list of size 1:: >>> request = TestRequest() >>> widget = zope.formlib.source.SourceDropdownWidget( ... dog, dog.source, request) >>> print widget() # doctest: +ELLIPSIS
 spot



We'll select an item by setting the appropriate fields in the request:: >>> request.form['field.dog-empty-marker'] = '1' >>> request.form['field.dog'] = 'bGFzc2ll' >>> >>> widget = zope.formlib.source.SourceRadioWidget( ... dog, dog.source, request) >>> print widget() # doctest: +NORMALIZE_WHITESPACE




For list-valued fields with items chosen from iterable sources, there are the SourceMultiSelectWidget and SourceOrderedMultiSelectWidget widgets. The latter widget includes support for re-ording the list items. SourceOrderedMultiSelectWidget is configured as the default widget for lists of choices. If you don't need ordering support through the web UI, then you can use the simpler SourceMultiSelectWidget:: >>> dogSource = SourceList([ ... u'spot', u'bowser', u'prince', u'duchess', u'lassie']) >>> dogs = zope.schema.List( ... __name__ = 'dogs', ... title=u"Dogs", ... value_type=zope.schema.Choice( ... source=dogSource, ... ) ... ) >>> dogs = dogs.bind(object()) # give the field a context >>> request = TestRequest() >>> widget = zope.formlib.source.SourceMultiSelectWidget( ... dogs, dogSource, request) Let's look at the rendered widget:: >>> print widget() # doctest: +NORMALIZE_WHITESPACE
We have no input yet:: >>> try: ... widget.getInputValue() ... except zope.formlib.interfaces.MissingInputError: ... print 'no input' no input Select an item:: >>> request.form['field.dogs-empty-marker'] = '1' >>> request.form['field.dogs'] = ['bGFzc2ll'] >>> widget.getInputValue() ['lassie'] and another:: >>> request.form['field.dogs'] = ['cHJpbmNl', 'bGFzc2ll'] >>> widget.getInputValue() ['prince', 'lassie'] Finally, what does the widget look like now:: >>> print widget() # doctest: +NORMALIZE_WHITESPACE
An alternative for small numbers of items is to use SourceMultiCheckBoxWidget:: >>> request = TestRequest() >>> widget = zope.formlib.source.SourceMultiCheckBoxWidget( ... dogs, dogSource, request) The rendered widget:: >>> print widget() # doctest: +NORMALIZE_WHITESPACE




We have no input yet:: >>> try: ... widget.getInputValue() ... except zope.formlib.interfaces.MissingInputError: ... print 'no input' no input Select an item:: >>> request.form['field.dogs-empty-marker'] = '1' >>> request.form['field.dogs'] = ['bGFzc2ll'] >>> widget.getInputValue() ['lassie'] and another:: >>> request.form['field.dogs'] = ['c3BvdA==', 'bGFzc2ll'] >>> widget.getInputValue() ['spot', 'lassie'] Finally, what does the widget look like now:: >>> print widget() # doctest: +NORMALIZE_WHITESPACE




For list ordering support, use SourceOrderedMultiSelectWidget:: >>> request = TestRequest() >>> widget = zope.formlib.source.SourceOrderedMultiSelectWidget( ... dogs, dogSource, request) The widget is too complicated to show in complete rendered form here. Insted, we'll inspect the properties of the widget:: >>> from zope.formlib.interfaces import MissingInputError >>> try: ... widget.getInputValue() ... except MissingInputError: ... print 'no input' no input >>> widget.choices() == [ ... {'text': u'spot', 'value': 'c3BvdA=='}, ... {'text': u'bowser', 'value': 'Ym93c2Vy'}, ... {'text': u'prince', 'value': 'cHJpbmNl'}, ... {'text': u'duchess', 'value': 'ZHVjaGVzcw=='}, ... {'text': u'lassie', 'value': 'bGFzc2ll'} ... ] True >>> widget.selected() [] Let's try out selecting items. Select one item:: >>> request.form['field.dogs-empty-marker'] = '1' >>> request.form['field.dogs'] = ['bGFzc2ll'] >>> widget.selected() # doctest: +NORMALIZE_WHITESPACE [{'text': u'lassie', 'value': 'bGFzc2ll'}] >>> widget.getInputValue() ['lassie'] Select two items:: >>> request.form['field.dogs'] = ['c3BvdA==', 'bGFzc2ll'] >>> widget.selected() # doctest: +NORMALIZE_WHITESPACE [{'text': u'spot', 'value': 'c3BvdA=='}, {'text': u'lassie', 'value': 'bGFzc2ll'}] >>> widget.getInputValue() ['spot', 'lassie'] For set-valued fields, use SourceMultiSelectSetWidget:: >>> dogSet = zope.schema.Set( ... __name__ = 'dogSet', ... title=u"Dogs", ... value_type=zope.schema.Choice( ... source=dogSource, ... ) ... ) >>> dogSet = dogSet.bind(object()) # give the field a context >>> request = TestRequest() >>> widget = zope.formlib.source.SourceMultiSelectSetWidget( ... dogSet, dogSource, request) >>> try: ... widget.getInputValue() ... except zope.formlib.interfaces.MissingInputError: ... print 'no input' no input >>> print widget() # doctest: +NORMALIZE_WHITESPACE
Let's try out selecting items. Select one item:: >>> request.form['field.dogSet-empty-marker'] = '1' >>> request.form['field.dogSet'] = ['bGFzc2ll'] >>> widget.getInputValue() set(['lassie']) Select two items:: >>> request.form['field.dogSet'] = ['c3BvdA==', 'bGFzc2ll'] >>> widget.getInputValue() set(['spot', 'lassie']) The rendered widget (still with the two items selected) looks like this:: >>> print widget() # doctest: +NORMALIZE_WHITESPACE
Source Widget Query Framework ============================= An important aspect of sources is that they may have too many values to enumerate. Rather than listing all of the values, we, instead, provide interfaces for querying values and selecting values from query results. Matters are further complicated by the fact that different sources may have very different interfaces for querying them. To make matters more interesting, a source may be an aggregation of several collections, each with their own querying facilities. An example of such a source is a principal source, where principals might come from a number of places, such as an LDAP database and ZCML-based principal definitions. The default widgets for selecting values from sources use the following approach: - One or more query objects are obtained from the source by adapting the source to `zope.schema.ISourceQueriables`. If no adapter is obtained, then the source itself is assumed to be queriable. - For each queriable found, a `zope.formlib.interfaces.ISourceQueryView` view is looked up. This view is used to obtain the HTML for displaying a query form. The view is also used to obtain search results. Let's start with a simple example. We have a very trivial source, which is basically a list: >>> class SourceList(list): ... zope.interface.implements(zope.schema.interfaces.ISource) We need to register our `ITerms` view:: >>> zope.component.provideAdapter( ... ListTerms, ... (SourceList, zope.publisher.interfaces.browser.IBrowserRequest)) We aren't going to provide an adapter to `ISourceQueriables`, so the source itself will be used as it's own queriable. We need to provide a query view for the source:: >>> class ListQueryView: ... ... zope.interface.implements( ... zope.formlib.interfaces.ISourceQueryView) ... zope.component.adapts( ... SourceList, ... zope.publisher.interfaces.browser.IBrowserRequest, ... ) ... ... def __init__(self, source, request): ... self.source = source ... self.request = request ... ... def render(self, name): ... return ( ... '\n' ... '' ... % (name, name) ... ) ... ... def results(self, name): ... if name in self.request: ... search_string = self.request.get(name+'.string') ... if search_string is not None: ... return [value ... for value in self.source ... if search_string in value ... ] ... return None >>> zope.component.provideAdapter(ListQueryView) Now, we can define a choice field:: >>> dog = zope.schema.Choice( ... __name__ = 'dog', ... title=u"Dogs", ... source=SourceList(['spot', 'bowser', 'prince', 'duchess', 'lassie']), ... ) As before, we'll just create the view directly:: >>> request = TestRequest() >>> widget = zope.formlib.source.SourceInputWidget( ... dog, dog.source, request) Now if we render the widget, we'll see the input value (initially nothing) and a form elements for seaching for values:: >>> print widget()
Selected
Nothing
This shows that we haven't selected a dog. We get a search box that we can type seach strings into. Let's supply a search string. We do this by providing data in the form and by "selecting" the submit button:: >>> request.form['field.dog.displayed'] = u'y' >>> request.form['field.dog.query.string'] = u'o' >>> request.form['field.dog.query'] = u'Search' Because the field is required, a non-selection is not valid. Thus, while the widget still hasInput, it will raise an error when you getInputValue:: >>> widget.hasInput() True >>> widget.getInputValue() Traceback (most recent call last): ... MissingInputError: ('dog', u'Dogs', None) If the field is not required:: >>> dog.required = False then as long as the field is displayed, the widget still has input but returns the field's missing value:: >>> widget.hasInput() True >>> widget.getInputValue() # None Now if we render the widget, we'll see the search results:: >>> dog.required = True >>> print widget()
Selected
Nothing
If we select an item:: >>> request.form['field.dog.displayed'] = u'y' >>> del request.form['field.dog.query.string'] >>> del request.form['field.dog.query'] >>> request.form['field.dog.query.selection'] = u'c3BvdA==' >>> request.form['field.dog.query.apply'] = u'Apply' Then we'll show the newly selected value:: >>> print widget()
Selected
spot
Note that we should have an input value now, since pressing the 'Apply' button provides us with input:: >>> widget.hasInput() True We should also be able to get the input value:: >>> widget.getInputValue() 'spot' Now, let's look at a more complicated example. We'll define a source that combines multiple sources:: >>> class MultiSource: ... ... zope.interface.implements( ... zope.schema.interfaces.ISource, ... zope.schema.interfaces.ISourceQueriables, ... ) ... ... def __init__(self, *sources): ... self.sources = [(unicode(i), s) for (i, s) in enumerate(sources)] ... ... def __contains__(self, value): ... for i, s in self.sources: ... if value in s: ... return True ... return False ... ... def getQueriables(self): ... return self.sources This multi-source implements `ISourceQueriables`. It assumes that the sources it's given are queriable and just returns the sources as the queryable objects. We can reuse our terms view:: >>> zope.component.provideAdapter( ... ListTerms, ... (MultiSource, zope.publisher.interfaces.browser.IBrowserRequest)) Now, we'll create a pet choice that combines dogs and cats:: >>> pet = zope.schema.Choice( ... __name__ = 'pet', ... title=u"Dogs and Cats", ... source=MultiSource( ... dog.source, ... SourceList(['boots', 'puss', 'tabby', 'tom', 'tiger']), ... ), ... ) and a widget:: >>> widget = zope.formlib.source.SourceInputWidget( ... pet, pet.source, request) Now if we display the widget, we'll see search inputs for both dogs and cats:: >>> print widget()
Selected
Nothing
As before, we can perform a search:: >>> request.form['field.pet.displayed'] = u'y' >>> request.form['field.pet.MQ__.string'] = u't' >>> request.form['field.pet.MQ__'] = u'Search' In which case, we'll get some results:: >>> print widget() # doctest:
Selected
Nothing
from which we can choose:: >>> request.form['field.pet.displayed'] = u'y' >>> del request.form['field.pet.MQ__.string'] >>> del request.form['field.pet.MQ__'] >>> request.form['field.pet.MQ__.selection'] = u'dGFiYnk=' >>> request.form['field.pet.MQ__.apply'] = u'Apply' and get a selection:: >>> print widget()
Selected
tabby
Note that we should have an input value now, since pressing the 'Apply' button provides us with input:: >>> widget.hasInput() True and we can get the input value:: >>> widget.getInputValue() 'tabby' There's a display widget, which doesn't use queriables, since it doesn't assign values:: >>> request = TestRequest() >>> widget = zope.formlib.source.SourceDisplayWidget( ... pet, pet.source, request) >>> print widget() Nothing >>> from zope.formlib.interfaces import IBrowserWidget >>> IBrowserWidget.providedBy(widget) True >>> widget.setRenderedValue('tabby') >>> print widget() tabby Like any good display widget, input is not required:: >>> widget.required False If we specify a list of choices:: >>> pets = zope.schema.List(__name__ = 'pets', title=u"Pets", ... value_type=pet) when a widget is computed for the field, a view will be looked up for the field and the source, where, in this case, the field is a list field. We'll just call the widget factory directly:: >>> widget = zope.formlib.source.SourceListInputWidget( ... pets, pets.value_type.source, request) If we render the widget:: >>> print widget()
Here the output looks very similar to the simple choice case. We get a search input for each source. In this case, we don't show any inputs (TODO we probably should make it clearer that there are no selected values.) As before, we can search one of the sources:: >>> request.form['field.pets.displayed'] = u'y' >>> request.form['field.pets.MQ__.string'] = u't' >>> request.form['field.pets.MQ__'] = u'Search' In which case, we'll get some results:: >>> print widget()
from which we can select some values:: >>> request.form['field.pets.displayed'] = u'y' >>> del request.form['field.pets.MQ__.string'] >>> del request.form['field.pets.MQ__'] >>> request.form['field.pets.MQ__.selection'] = [ ... u'dGFiYnk=', u'dGlnZXI=', u'dG9t'] >>> request.form['field.pets.MQ__.apply'] = u'Apply' Which then leads to the selections appearing as widget selections:: >>> print widget()
tabby
tiger
tom

We can get the selected values:: >>> widget.getInputValue() ['tabby', 'tiger', 'tom'] We now see the values we selected. We also have checkboxes and buttons that allow us to remove selections:: >>> request.form['field.pets.displayed'] = u'y' >>> request.form['field.pets'] = [u'dGFiYnk=', u'dGlnZXI=', u'dG9t'] >>> del request.form['field.pets.MQ__.selection'] >>> del request.form['field.pets.MQ__.apply'] >>> request.form['field.pets.checked'] = [u'dGFiYnk=', u'dG9t'] >>> request.form['field.pets.remove'] = u'Remove' >>> print widget()
tiger

Using vocabulary-dependent widgets with sources =============================================== if you have a widget that uses old-style vocabularies but don't have the time to rewrite it for sources, all is not lost! The wrapper IterableSourceVocabulary can be used to make sources and ITerms look like a vocabulary. This allows us to use vocabulary-based widgets with sources instead of vocabularies. Usage:: >>> from zope.schema.vocabulary import SimpleTerm >>> values = [u'a', u'b', u'c'] >>> tokens = [ '0', '1', '2'] >>> titles = [u'A', u'B', u'C'] >>> terms = [SimpleTerm(values[i], token=tokens[i], title=titles[i]) \ ... for i in range(0,len(values))] >>> class TestSource(list): ... zope.interface.implements(zope.schema.interfaces.IIterableSource) >>> source = TestSource(values) >>> class TestTerms(object): ... zope.interface.implements(ITerms) ... def __init__(self, source, request): ... pass ... def getTerm(self, value): ... index = values.index(value) ... return terms[index] ... def getValue(self, token): ... index = tokens.index(token) ... return values[index] >>> zope.component.provideAdapter( ... TestTerms, ... (TestSource, zope.publisher.interfaces.browser.IBrowserRequest)) >>> from zope.formlib.source import IterableSourceVocabulary >>> request = TestRequest() >>> vocab = IterableSourceVocabulary(source, request) >>> from zope.interface.verify import verifyClass, verifyObject >>> verifyClass(zope.schema.interfaces.IVocabularyTokenized, \ ... IterableSourceVocabulary) True >>> verifyObject(zope.schema.interfaces.IVocabularyTokenized, vocab) True >>> len(vocab) 3 >>> (u'a' in vocab) and (u'b' in vocab) and (u'c' in vocab) True >>> [value for value in vocab] == terms True >>> term = vocab.getTerm(u'b') >>> (term.value, term.token, term.title) (u'b', '1', u'B') >>> term = vocab.getTermByToken('2') >>> (term.value, term.token, term.title) (u'c', '2', u'C')