owl2django.py

from lxml import etree

# This string will contain the models.py file
modelsContents = "from neo4django.db import models\n\n"

# Enter the name of the OWL file to parse
# The relationships in the file should always start with has...
owlFile = "ontology.owl"

# Gives the ontology URI. Only needed for documentation purposes
ontologyURI = "http://www.semanticweb.org/nkb/ontologies/2013/6/impact-investment#"

# Adds a comment in the models.py file
modelsContents += "# The ontology can be found in its entirety at " + ontologyURI + "\n"

# Defines the owl and rdf namespaces
namespaces = {
	'owl': 'http://www.w3.org/2002/07/owl#', 
	'rdf': 'http://www.w3.org/1999/02/22-rdf-syntax-ns#', 
	'rdfs': 'http://www.w3.org/2000/01/rdf-schema#'
	}

# This array contains the correspondance between data types
correspondanceTypes = {
	"string" : "StringProperty",
	"anyURI" : "URLProperty",
	"int" : "IntegerProperty",
	"nonNegativeInteger" : "IntegerProperty",
	"nonPositiveInteger" : "IntegerProperty",
	"PositiveInteger" : "IntegerProperty",
	"NegativeInteger" : "IntegerProperty",
	"integer" : "IntegerProperty",
	"dateTimeStamp" : "DateTimeProperty",
	"dateTime" : "DateTimeProperty",
	"string" : "StringArrayProperty",
	"boolean" : "BooleanProperty"
}

# Parses the file with etree
tree = etree.parse(owlFile)
root = tree.getroot()

# Finds all the Classes
for ontologyClassElement in root.findall("owl:Class", namespaces):

	# Defines the array that contains the class information
	ontologyClass = {}

	# Finds the URI of the class
	classURI = ontologyClassElement.attrib["{http://www.w3.org/1999/02/22-rdf-syntax-ns#}about"]

	#Finds the name of the class

	className = classURI.split("#")[1]

	# By default, the class has no parent
	parentClass = "models.NodeModel"

	# Declares an array to store the relationships and properties from this class
	relations = []
	properties = []

	# Finds all the subClasses of the Class
	for subClassElement in ontologyClassElement.findall("rdfs:subClassOf", namespaces):

		# If the Class is actually an extension of another Class
		if "{http://www.w3.org/1999/02/22-rdf-syntax-ns#}resource" in subClassElement.attrib:

			parentClassURI = subClassElement.attrib["{http://www.w3.org/1999/02/22-rdf-syntax-ns#}resource"]
			parentClass = parentClassURI.split("#")[1]		

		else:

			for restriction in subClassElement.findall("owl:Restriction", namespaces):

				# If there is a relationship defined in the subclass
				if restriction.find("owl:onClass", namespaces) is not None:

					# Finds the relationship and its elements (destination Class and type)
					relationClass = restriction.find("owl:onClass", namespaces)	
					relation = {}	
					relation["URI"] = relationClass.attrib["{http://www.w3.org/1999/02/22-rdf-syntax-ns#}resource"]	
					relation["name"] = relation["URI"].split("#")[1]

					# Exception when the relation's destination is an individual from the same class
					if relation["name"] == className:

						relation["name"] = 'self'

					relationType = restriction.find("owl:onProperty", namespaces)
					relationTypeURI = relationType.attrib["{http://www.w3.org/1999/02/22-rdf-syntax-ns#}resource"]
					relation["type"] = relationTypeURI.split("#")[1]

					# Guesses the destination of the relation based on the name. Name should be "has..."
					if relation["type"].find('has') == 0:
						relation["destination"] = relation["type"][3:].lower()

					# Adds the relationship to the array containing all relationships for the class only if the relation has a destination				
					if "destination" in relation:
						relations.append(relation)

				# If there is a property defined in the subclass
				elif restriction.find("owl:onDataRange", namespaces) is not None or restriction.find("owl:someValuesFrom", namespaces) is not None:
					propertyTypeElement = restriction.find("owl:onProperty", namespaces)
					propertyTypeURI = propertyTypeElement.attrib["{http://www.w3.org/1999/02/22-rdf-syntax-ns#}resource"]
					propertyType = propertyTypeURI.split("#")[1]
					if restriction.find("owl:onDataRange", namespaces) is not None:
						dataTypeElement = restriction.find("owl:onDataRange", namespaces)
					else:
						dataTypeElement = restriction.find("owl:someValuesFrom", namespaces)
					dataTypeURI = dataTypeElement.attrib["{http://www.w3.org/1999/02/22-rdf-syntax-ns#}resource"]
					dataType = correspondanceTypes[dataTypeURI.split("#")[1]]
					
					prop = {
						"name" : propertyType,
						"type" : dataType
					}

					properties.append(prop)

	# Writes the class in models.py
	modelsContents += "\nclass "+ className +"(" + parentClass + "):\n"

	# Writes the properties	
	for prop in properties:	
		modelsContents += "\t" + prop["name"] + " = models." + prop["type"] + "()\n"

	# Writes the relationships
	for relation in relations:	
		modelsContents += "\t" + relation["destination"] + " = models.Relationship(" + relation["name"] + ",rel_type='" + relation["type"] + "')\n"


	if len(properties) == 0 and len(relations) == 0:
		modelsContents += "\tpass" # Avoid empty blocks

print modelsContents