diff options
Diffstat (limited to 'stackexchange/parse_models.py')
| -rw-r--r-- | stackexchange/parse_models.py | 145 |
1 files changed, 119 insertions, 26 deletions
diff --git a/stackexchange/parse_models.py b/stackexchange/parse_models.py index e83ca0d5..64796e57 100644 --- a/stackexchange/parse_models.py +++ b/stackexchange/parse_models.py @@ -1,14 +1,24 @@ 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.BooleanField', + 'boolean':'models.NullBooleanField', 'dateTime':'models.DateTimeField', 'base64Binary':'models.TextField', 'double':'models.IntegerField', @@ -26,15 +36,22 @@ def singular(word): 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 = 'StackExchange' - if name.find('2') == -1: - self.name += singular(name) - else: - bits = name.split('2') - bits = map(singular, bits) - self.name += '2'.join(bits) + self.name = get_table_name(name) self.fields = [] def add_field(self,field): field.table = self @@ -57,20 +74,31 @@ class DjangoField(object): def __str__(self): out = '%s = %s(' % (self.name, types[self.type]) - if self.relation and self.restriction: - raise Exception('impossible') - elif self.relation: + if self.type == 'FK': out += "'%s'" % self.relation - out += ", related_name='%s_%s_set'" % (self.table.name, self.name) + 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('only max_length restriction is supported') + 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') @@ -83,7 +111,7 @@ class DjangoFK(DjangoField): """some relations need to be mapped to actual tables """ - self.relation = 'StackExchange' + self.relation = table_prefix if name.endswith('User'): self.relation += 'User' elif name.endswith('Post'): @@ -92,6 +120,8 @@ class DjangoFK(DjangoField): 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') @@ -108,25 +138,88 @@ def get_col_type(col): 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 = file.replace('.xsd','') + tname = os.path.basename(file).replace('.xsd','') tree = et.parse(file) model = DjangoModel(tname) row = tree.find('.//sequence') for col in row.getchildren(): - name = col.get('name') - if name in ('Id', 'LinkedVoteId'):#second one is not used - continue - 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(col) - field = DjangoField(name, type, restriction) - model.add_field(field) + field = make_field_from_xml_tree(col) + if field: + model.add_field(field) print model |