yafowil.yaml YAML parser for widget trees
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forms yaml YAML parser yafowil YAFOWIL forms widget trees

yafowil.yaml Description

YAML parser for widget trees yafowil.yaml is a Python module to describe YAFOWIL forms in YAML.UsageCreate YAML file containing form descriptionfactory: formname: demo_formprops: action: context.form_actionwidgets:- title: factory: label:field:error:text value: expr:context.get('title', '') props: label: Title required: No title given- description: factory: label:field:textarea value: expr:context.get('description', '') props: label: Description rows: 5- save: factory: submit props: action: save expression: True handler: context.save next: context.next label: SaveEach widget node is represented by an associative array. Keys are mapping to corresponding arguments of yafowil.base.factory signature:factory Chained factory registration names.name Widget name. Only required on root, for children widget key is used.value Widget value or callable/expression returning widget value.props Widget properties as associative array.custom Custom widget properties as associative array.widgets Child widgets as list. Each child widget is an associative array with one key - the widget name - containing again an associative array with the keys descibed here.Resolution of definition valuesBeside static values, definitions may contain python expressions, access to a rendering context and pointers to callables.- If definition value starts with expr:, a callback wrapper is created which gets executed each time the widget tree gets rendered. For security reasons, only rendering context is accessible in expressions.- If definition value starts with context, rendering context is used to lookup callbacks. If lookup fails, return definition value as string.- If '.' is found in definition value, try to lookup callback from module path. If lookup fails, return definition value as string.Define rendering contextA rendering context is provided by a class. Refering to the form description example above, this looks like:>>> class FormRenderingContext(object):...... def get(self, key, default=None):... # do data lookup here... value = key... return value...... def form_action(self, widget, data):... # create and return form action URL... return 'http://example.com/form_action'...... def save(self, widget, data):... # extract and save form data... pass...... def next(self, request):... # compute and return next URL... return 'http://example.com/form_action_succeed'To obtain a yafowil widget tree from YAML, use yafowil.yaml.parse_from_YAML:>>> import yafowil.loader>>> from yafowil.yaml import parse_from_YAML>>> rendering_context = FormRenderingContext()>>> form = parse_from_YAML(demo_form_path, context=rendering_context)This results to...:>>> form.printtree()< class 'yafowil.base.Widget' >: demo_form < class 'yafowil.base.Widget' >: title < class 'yafowil.base.Widget' >: description < class 'yafowil.base.Widget' >: save...which renders: > > > pxml(form())< form action="http://example.com/form_action" enctype="multipart/form-data" id="form-demo_form" method="post" > < label for="input-demo_form-title" >Title< /label > < div class="field" id="field-demo_form-title" > < input class="required text" id="input-demo_form-title" name="demo_form.title" required="required" type="text" value="title"/ > < /div > < label for="input-demo_form-description" >Description< /label > < div class="field" id="field-demo_form-description" > < textarea cols="80" id="input-demo_form-description" name="demo_form.description" rows="5" >description< /textarea > < /div > < input id="input-demo_form-save" name="action.demo_form.save" type="submit" value="Save"/ >< /form >< BLANKLINE > Requirements: · Python What's New in This Release: · Make it work

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