Package: validify
validifyis a rule-based validation module for assessing the structure of an xml tree, written in Python and built on top of thelxmllibrary. It currently covers a subset of the XML Schema 1.1 Definition.RequirementsPython 3.5+lxmlloguruInstallationThevalidifymodule can be found onPyPI.
It can be installed by using pip:pip install validifyDependencies will be automatically fetched by pip.Basic usageimportvalidifyvalidation_result=validify.validate(input_file="validify/test.xml",input_elementtree=None,xmlns_def=None,validation_rules=None,message_lang=None,log_to_console=True,log_debug=False)Parametersinput_file (default:None): path to xml file which should be validated.input_elementtree (default:None): an etree.ElementTree object (parameter 'input_elementtree') can also be passed, instead of an input file string.xmlns_def (default:None): a namespace definition can be supplied as a python dictionary object ({None: "default_namespace", "namespace_prefix": "another_namespace"}}).validation_rules (default:None): a python dictionary object containing the validation rules (see "Defining validation rules" below for an example.). An example rules dictionary is used if no value is supplied here.message_lang (default:de): language for validation message strings. Supported values areenandde.log_to_console (default:True): ifTrue, validation and status messages are logged to console. If false, validation messages are only added to the results dict returned byvalidfy.log_debug (default:False): ifTrue, debug status messages are logged to console.One of the paramatersinput_fileorinput_elementtreeshould be passed for the library to produce validation results.Defining validation rulesValidation rules are defined in a dictionary object (JSON-like structure):validation_rules={}validation_rules["element"]=[]ruleset={}ruleset["element_content_optional"]=Falseruleset["element_children_optional"]=Falseruleset["optional_attributes"]=["valid_optional_attribute_01","valid_optional_attribute_02"]ruleset["obligatory_attributes"]=["obligatory_attribute_01","obligatory_attribute_02"]ruleset["optional_subelements"]=["optional_subelement_01","optional_subelement_02"]ruleset["obligatory_subelements"]=["obligatory_subelement_01","obligatory_subelement_02"]ruleset["max_occurence"]=2ruleset["text_character_content_allowed"]=Trueruleset["tail_character_content_allowed"]=Falseruleset["allowed_values"]=["valid_value_01","valid_value_02"]ruleset["allowed_patterns"]=["^test-\d{4}$","^test-\d{3}$"]ruleset["allowed_datatypes"]=[]ruleset["attribute_def"]=[]ruleset["attribute_def"].append({"attribute_name":"valid_optional_attribute_01","allowed_values":["valid_value_01","valid_value_02"],"allowed_patterns":["^test-\d{4}$","^test-\d{3}$"]})ruleset["attribute_def"].append({"attribute_name":"obligatory_attribute_01","allowed_values":["valid_value_01","valid_value_02"],"allowed_patterns":[]})ruleset["rule_conditions"]=[]ruleset["rule_conditions"].append({"text_values":["valid_text_value"],"attribute_def":[{"attribute_name":"valid_attribute_name","allowed_values":["valid_value"]},{"attribute_name":"another_valid_attribute_name","allowed_values":["valid_value"]}],"reference_elements":[{"element_name":"reference_element","attribute_def":[{"attribute_name":"reference_test","allowed_values":["valid_value"]}],"preceding_elements":1}]})validation_rules["element"].append(ruleset)Each element can be provided with one or more rulesets.
Therule_conditionsdefiniton can be used when the ruleset should only be applied if the validated element contains the defined attribute(s) and attribute value(s). Besides the validated element, a reference element can also be defined and checked for attribute values. Currently, it must be a parent element of the validated element (parent level defined bypreceding_elements).Validation outputvalidify.validatereturns a list containing the validation messages as dictionaries:[{'message_id':'0001','message_text ':'Element example_element does not contain any subelements, although one or more subelements are expected.','element_name':'{namespace}example_element','local_name':'example_element','element_sourceline':'23'}]XML Schema feature coverageFor now, a small subset of theXML Schemafeatures is provided:Test if a ruleset applies by checking a reference element's text and attribute valuesDefine if element childen and content are optionalDefine optional and obligatory attributesDefine optional and obligatory subelementsDefine maximum occurence of an elementDefine if character content is allowedDefine an element's allowed values (~ xs:enumeration)Define an element's allowed patterns (~ xs:pattern)Define an attribute's allowed values and patternsThis module is currently used for validating data deliveries in theEAD XML application profile, which are processed for ingesting in the metadata portalsDeutsche Digitale BibliothekandArchivportal-D. Therefore, supported features currently are nowhere near those provided by the XML Schema standard. Feature support is supposed to be gradually expanded, however.The following features are planned for a future release:checking max/min text and attribute valuesvalidating string lengthsupport for pre-defined data types (i.e.xs:ID,xs:NMTOKEN)rule conditions: direct support for XPath and lxml'sitersiblingsanditerancestorsmethods.Development statusThis package is in an early development stage. It should already work reliably for intended use cases, but documentation and stability of API are still lacking.