268 lines
12 KiB
Python
268 lines
12 KiB
Python
from __future__ import unicode_literals
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import keyword
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import re
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from collections import OrderedDict
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from django.core.management.base import BaseCommand, CommandError
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from django.db import DEFAULT_DB_ALIAS, connections
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class Command(BaseCommand):
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help = "Introspects the database tables in the given database and outputs a Django model module."
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requires_system_checks = False
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db_module = 'django.db'
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def add_arguments(self, parser):
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parser.add_argument('--database', action='store', dest='database',
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default=DEFAULT_DB_ALIAS, help='Nominates a database to '
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'introspect. Defaults to using the "default" database.')
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def handle(self, **options):
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try:
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for line in self.handle_inspection(options):
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self.stdout.write("%s\n" % line)
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except NotImplementedError:
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raise CommandError("Database inspection isn't supported for the currently selected database backend.")
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def handle_inspection(self, options):
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connection = connections[options['database']]
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# 'table_name_filter' is a stealth option
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table_name_filter = options.get('table_name_filter')
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table2model = lambda table_name: re.sub(r'[^a-zA-Z0-9]', '', table_name.title())
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strip_prefix = lambda s: s[1:] if s.startswith("u'") else s
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with connection.cursor() as cursor:
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yield "# This is an auto-generated Django model module."
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yield "# You'll have to do the following manually to clean this up:"
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yield "# * Rearrange models' order"
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yield "# * Make sure each model has one field with primary_key=True"
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yield "# * Make sure each ForeignKey has `on_delete` set to the desidered behavior."
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yield (
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"# * Remove `managed = False` lines if you wish to allow "
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"Django to create, modify, and delete the table"
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)
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yield "# Feel free to rename the models, but don't rename db_table values or field names."
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yield "from __future__ import unicode_literals"
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yield ''
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yield 'from %s import models' % self.db_module
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known_models = []
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for table_name in connection.introspection.table_names(cursor):
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if table_name_filter is not None and callable(table_name_filter):
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if not table_name_filter(table_name):
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continue
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yield ''
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yield ''
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yield 'class %s(models.Model):' % table2model(table_name)
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known_models.append(table2model(table_name))
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try:
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relations = connection.introspection.get_relations(cursor, table_name)
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except NotImplementedError:
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relations = {}
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try:
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indexes = connection.introspection.get_indexes(cursor, table_name)
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except NotImplementedError:
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indexes = {}
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try:
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constraints = connection.introspection.get_constraints(cursor, table_name)
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except NotImplementedError:
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constraints = {}
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used_column_names = [] # Holds column names used in the table so far
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for row in connection.introspection.get_table_description(cursor, table_name):
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comment_notes = [] # Holds Field notes, to be displayed in a Python comment.
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extra_params = OrderedDict() # Holds Field parameters such as 'db_column'.
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column_name = row[0]
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is_relation = column_name in relations
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att_name, params, notes = self.normalize_col_name(
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column_name, used_column_names, is_relation)
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extra_params.update(params)
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comment_notes.extend(notes)
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used_column_names.append(att_name)
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# Add primary_key and unique, if necessary.
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if column_name in indexes:
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if indexes[column_name]['primary_key']:
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extra_params['primary_key'] = True
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elif indexes[column_name]['unique']:
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extra_params['unique'] = True
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if is_relation:
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rel_to = (
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"self" if relations[column_name][1] == table_name
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else table2model(relations[column_name][1])
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)
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if rel_to in known_models:
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field_type = 'ForeignKey(%s' % rel_to
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else:
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field_type = "ForeignKey('%s'" % rel_to
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else:
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# Calling `get_field_type` to get the field type string and any
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# additional parameters and notes.
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field_type, field_params, field_notes = self.get_field_type(connection, table_name, row)
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extra_params.update(field_params)
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comment_notes.extend(field_notes)
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field_type += '('
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# Don't output 'id = meta.AutoField(primary_key=True)', because
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# that's assumed if it doesn't exist.
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if att_name == 'id' and extra_params == {'primary_key': True}:
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if field_type == 'AutoField(':
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continue
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elif field_type == 'IntegerField(' and not connection.features.can_introspect_autofield:
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comment_notes.append('AutoField?')
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# Add 'null' and 'blank', if the 'null_ok' flag was present in the
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# table description.
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if row[6]: # If it's NULL...
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if field_type == 'BooleanField(':
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field_type = 'NullBooleanField('
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else:
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extra_params['blank'] = True
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extra_params['null'] = True
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field_desc = '%s = %s%s' % (
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att_name,
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# Custom fields will have a dotted path
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'' if '.' in field_type else 'models.',
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field_type,
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)
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if field_type.startswith('ForeignKey('):
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field_desc += ', models.DO_NOTHING'
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if extra_params:
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if not field_desc.endswith('('):
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field_desc += ', '
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field_desc += ', '.join(
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'%s=%s' % (k, strip_prefix(repr(v)))
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for k, v in extra_params.items())
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field_desc += ')'
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if comment_notes:
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field_desc += ' # ' + ' '.join(comment_notes)
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yield ' %s' % field_desc
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for meta_line in self.get_meta(table_name, constraints):
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yield meta_line
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def normalize_col_name(self, col_name, used_column_names, is_relation):
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"""
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Modify the column name to make it Python-compatible as a field name
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"""
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field_params = {}
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field_notes = []
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new_name = col_name.lower()
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if new_name != col_name:
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field_notes.append('Field name made lowercase.')
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if is_relation:
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if new_name.endswith('_id'):
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new_name = new_name[:-3]
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else:
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field_params['db_column'] = col_name
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new_name, num_repl = re.subn(r'\W', '_', new_name)
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if num_repl > 0:
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field_notes.append('Field renamed to remove unsuitable characters.')
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if new_name.find('__') >= 0:
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while new_name.find('__') >= 0:
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new_name = new_name.replace('__', '_')
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if col_name.lower().find('__') >= 0:
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# Only add the comment if the double underscore was in the original name
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field_notes.append("Field renamed because it contained more than one '_' in a row.")
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if new_name.startswith('_'):
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new_name = 'field%s' % new_name
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field_notes.append("Field renamed because it started with '_'.")
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if new_name.endswith('_'):
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new_name = '%sfield' % new_name
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field_notes.append("Field renamed because it ended with '_'.")
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if keyword.iskeyword(new_name):
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new_name += '_field'
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field_notes.append('Field renamed because it was a Python reserved word.')
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if new_name[0].isdigit():
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new_name = 'number_%s' % new_name
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field_notes.append("Field renamed because it wasn't a valid Python identifier.")
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if new_name in used_column_names:
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num = 0
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while '%s_%d' % (new_name, num) in used_column_names:
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num += 1
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new_name = '%s_%d' % (new_name, num)
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field_notes.append('Field renamed because of name conflict.')
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if col_name != new_name and field_notes:
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field_params['db_column'] = col_name
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return new_name, field_params, field_notes
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def get_field_type(self, connection, table_name, row):
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"""
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Given the database connection, the table name, and the cursor row
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description, this routine will return the given field type name, as
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well as any additional keyword parameters and notes for the field.
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"""
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field_params = OrderedDict()
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field_notes = []
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try:
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field_type = connection.introspection.get_field_type(row[1], row)
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except KeyError:
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field_type = 'TextField'
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field_notes.append('This field type is a guess.')
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# This is a hook for data_types_reverse to return a tuple of
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# (field_type, field_params_dict).
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if type(field_type) is tuple:
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field_type, new_params = field_type
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field_params.update(new_params)
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# Add max_length for all CharFields.
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if field_type == 'CharField' and row[3]:
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field_params['max_length'] = int(row[3])
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if field_type == 'DecimalField':
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if row[4] is None or row[5] is None:
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field_notes.append(
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'max_digits and decimal_places have been guessed, as this '
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'database handles decimal fields as float')
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field_params['max_digits'] = row[4] if row[4] is not None else 10
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field_params['decimal_places'] = row[5] if row[5] is not None else 5
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else:
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field_params['max_digits'] = row[4]
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field_params['decimal_places'] = row[5]
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return field_type, field_params, field_notes
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def get_meta(self, table_name, constraints):
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"""
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Return a sequence comprising the lines of code necessary
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to construct the inner Meta class for the model corresponding
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to the given database table name.
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"""
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unique_together = []
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for index, params in constraints.items():
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if params['unique']:
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columns = params['columns']
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if len(columns) > 1:
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# we do not want to include the u"" or u'' prefix
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# so we build the string rather than interpolate the tuple
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tup = '(' + ', '.join("'%s'" % c for c in columns) + ')'
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unique_together.append(tup)
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meta = ["",
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" class Meta:",
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" managed = False",
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" db_table = '%s'" % table_name]
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if unique_together:
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tup = '(' + ', '.join(unique_together) + ',)'
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meta += [" unique_together = %s" % tup]
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return meta
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