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-rw-r--r--stackexchange/parse_models.py225
1 files changed, 225 insertions, 0 deletions
diff --git a/stackexchange/parse_models.py b/stackexchange/parse_models.py
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+++ b/stackexchange/parse_models.py
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+from xml.etree import ElementTree as et
+import sys
+import re
+import os
+if __name__ != '__main__':#hack do not import models if run as script
+ from django.db import models
+from datetime import datetime
+
+table_prefix = ''#StackExchange or something, if needed
+date_time_format = '%Y-%m-%dT%H:%M:%S' #note that fractional part of second is lost
+time_re = re.compile(r'(\.[\d]+)?$')
+loader_app_name = os.path.dirname(__file__)
+
+types = {
+ 'unsignedByte':'models.IntegerField',
+ 'FK':'models.ForeignKey',
+ 'PK':'models.IntegerField',
+ 'string':'models.CharField',
+ 'text':'models.TextField',
+ 'int':'models.IntegerField',
+ 'boolean':'models.NullBooleanField',
+ 'dateTime':'models.DateTimeField',
+ 'base64Binary':'models.TextField',
+ 'double':'models.IntegerField',
+}
+
+def camel_to_python(camel):
+ """http://stackoverflow.com/questions/1175208/
+ """
+ s1 = re.sub('(.)([A-Z][a-z]+)', r'\1_\2', camel)
+ return re.sub('([a-z0-9])([A-Z])', r'\1_\2', s1).lower()
+
+def singular(word):
+ if word.endswith('s'):
+ return word[:-1]
+ else:
+ return word
+
+def get_table_name(name):
+ """Determine db table name
+ from the basename of the .xml file
+ """
+ out = table_prefix
+ if name.find('2') == -1:
+ out += singular(name)
+ else:
+ bits = name.split('2')
+ bits = map(singular, bits)
+ out += '2'.join(bits)
+ return out
+
+class DjangoModel(object):
+ def __init__(self, name):
+ self.name = get_table_name(name)
+ self.fields = []
+ def add_field(self,field):
+ field.table = self
+ self.fields.append(field)
+ def __str__(self):
+ out = 'class %s(models.Model):\n' % self.name
+ for f in self.fields:
+ out += ' %s\n' % str(f)
+ return out
+
+class DjangoField(object):
+ def __init__(self, name, type, restriction = None):
+ self.name = camel_to_python(name)
+ if self.name == 'class':
+ self.name = 'class_type'#work around python keyword
+ self.type = type
+ self.table = None
+ self.restriction = restriction
+ self.relation = None
+
+ def __str__(self):
+ out = '%s = %s(' % (self.name, types[self.type])
+ if self.type == 'FK':
+ out += "'%s'" % self.relation
+ out += ", related_name='%s_by_%s_set'" % (self.table.name, self.name)
+ out += ', null=True'#nullable to make life easier
+ elif self.type == 'PK':
+ out += 'primary_key=True'
+ elif self.restriction != -1:
+ if self.type == 'string':
+ out += 'max_length=%s' % self.restriction
+ out += ', null=True'
+ else:
+ raise Exception('restriction (max_length) supported only for string type')
+ else:
+ out += 'null=True'
+ out += ')'
+ return out
+
+ def get_type(self):
+ return self.type
+
+class DjangoPK(DjangoField):
+ def __init__(self):
+ self.name = 'id'
+ self.type = 'PK'
+
+class DjangoFK(DjangoField):
+ def __init__(self, source_name):
+ bits = source_name.split('Id')
+ if len(bits) == 2 and bits[1] == '':
+ name = bits[0]
+ super(DjangoFK, self).__init__(name, 'FK')
+ self.set_relation(name)
+
+ def set_relation(self, name):
+ """some relations need to be mapped
+ to actual tables
+ """
+ self.relation = table_prefix
+ if name.endswith('User'):
+ self.relation += 'User'
+ elif name.endswith('Post'):
+ self.relation += 'Post'
+ elif name in ('AcceptedAnswer','Parent'):
+ self.relation = 'self' #self-referential Post model
+ else:
+ self.relation += name
+ def get_relation(self):
+ return self.relation
+
+def get_col_type(col):
+ type = col.get('type')
+ restriction = -1
+ if type == None:
+ type_e = col.find('.//simpleType/restriction')
+ type = type_e.get('base')
+ try:
+ restriction = int(type_e.getchildren()[0].get('value'))
+ except:
+ restriction = -1
+ if restriction > 400:
+ type = 'text'
+ restriction = -1
+ return type, restriction
+
+def make_field_from_xml_tree(xml_element):
+ """used by the model parser
+ here we need to be detailed about field types
+ because this defines the database schema
+ """
+ name = xml_element.get('name')
+ if name == 'LinkedVoteId':#not used
+ return None
+ if name == 'Id':
+ field = DjangoPK()
+ elif name.endswith('Id') and name not in ('OpenId','PasswordId'):
+ field = DjangoFK(name)
+ elif name.endswith('GUID'):
+ field = DjangoField(name, 'string', 64)
+ else:
+ type, restriction = get_col_type(xml_element)
+ field = DjangoField(name, type, restriction)
+ return field
+
+def parse_field_name(input):
+ """used by the data reader
+
+ The problem is that I've scattered
+ code for determination of field name over three classes:
+ DjangoField, DjangoPK and DjangoFK
+ so the function actually cretes fake field objects
+ many time over
+ """
+ if input == 'Id':
+ return DjangoPK().name
+ elif input in ('OpenId', 'PasswordId'):
+ return DjangoField(input, 'string', 7).name#happy fake field
+ elif input.endswith('Id'):
+ return DjangoFK(input).name#real FK field
+ else:
+ return DjangoField(input, 'string', 7).name#happy fake field
+
+def parse_value(input, field_object):
+ if isinstance(field_object, models.ForeignKey):
+ try:
+ id = int(input)
+ except:
+ raise Exception('non-numeric foreign key %s' % input)
+ related_model = field_object.rel.to
+ try:
+ return related_model.objects.get(id=id)
+ except related_model.DoesNotExist:
+ obj = related_model(id=id)
+ obj.save()#save fake empty object
+ return obj
+ elif isinstance(field_object, models.IntegerField):
+ try:
+ return int(input)
+ except:
+ raise Exception('expected integer, found %s' % input)
+ elif isinstance(field_object, models.CharField):
+ return input
+ elif isinstance(field_object, models.TextField):
+ return input
+ elif isinstance(field_object, models.BooleanField):
+ try:
+ return bool(input)
+ except:
+ raise Exception('boolean value expected %s found' % input)
+ elif isinstance(field_object, models.DateTimeField):
+ input = time_re.sub('', input)
+ try:
+ return datetime.strptime(input, date_time_format)
+ except:
+ raise Exception('datetime expected "%s" found' % input)
+
+print 'from django.db import models'
+for file in sys.argv:
+ if '.xsd' in file:
+ tname = os.path.basename(file).replace('.xsd','')
+ tree = et.parse(file)
+
+ model = DjangoModel(tname)
+
+ row = tree.find('.//sequence')
+ for col in row.getchildren():
+ field = make_field_from_xml_tree(col)
+ if field:
+ model.add_field(field)
+ print model