created model parser and initial models for stackexchange importer

1 files changed, 132 insertions, 0 deletions

diff --git a/stackexchange/parse_models.py b/stackexchange/parse_models.py
new file mode 100644
index 00000000..e83ca0d5
--- /dev/null
+++ b/stackexchange/parse_models.py
@@ -0,0 +1,132 @@
+from xml.etree import ElementTree as et
+import sys
+import re
+
+types = {
+   'unsignedByte':'models.IntegerField',
+   'FK':'models.ForeignKey',
+   'string':'models.CharField',
+   'text':'models.TextField',
+   'int':'models.IntegerField',
+   'boolean':'models.BooleanField',
+   '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
+
+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.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.relation and self.restriction:
+            raise Exception('impossible')
+        elif self.relation:
+            out += "'%s'" % self.relation  
+            out += ", related_name='%s_%s_set'" % (self.table.name, self.name)
+            out += ', null=True'#nullable to make life easier
+        elif self.restriction != -1:
+            if self.type == 'string':
+                out += 'max_length=%s' % self.restriction
+            else:
+                raise Exception('only max_length restriction is supported')
+        out += ')'
+        return out
+
+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 = 'StackExchange'
+        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_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
+
+print 'from django.db import models'
+for file in sys.argv:
+    if '.xsd' in file:
+        tname = 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)
+        print model