Ticket #1483: 1483-clean.diff

File 1483-clean.diff, 2.8 KB (added by adrian, 9 years ago)

Cleaner version of patch (refactored some of it)

  • django/db/backends/mysql/introspection.py

     
    11from django.db import transaction
    22from django.db.backends.mysql.base import quote_name
     3from MySQLdb import ProgrammingError, OperationalError
    34from MySQLdb.constants import FIELD_TYPE
     5import re
    46
     7foreign_key_re = re.compile(r"\sCONSTRAINT `[^`]*` FOREIGN KEY \(`([^`]*)`\) REFERENCES `([^`]*)` \(`([^`]*)`\)")
     8
    59def get_table_list(cursor):
    610    "Returns a list of table names in the current database."
    711    cursor.execute("SHOW TABLES")
     
    1216    cursor.execute("SELECT * FROM %s LIMIT 1" % quote_name(table_name))
    1317    return cursor.description
    1418
     19def _name_to_index(cursor, table_name):
     20    """
     21    Returns a dictionary of {field_name: field_index} for the given table.
     22    Indexes are 0-based.
     23    """
     24    return dict([(d[0], i) for i, d in enumerate(get_table_description(cursor, table_name))])
     25
    1526def get_relations(cursor, table_name):
    16     raise NotImplementedError
     27    """
     28    Returns a dictionary of {field_index: (field_index_other_table, other_table)}
     29    representing all relationships to the given table. Indexes are 0-based.
     30    """
     31    my_field_dict = _name_to_index(cursor, table_name)
     32    constraints = []
     33    relations = {}
     34    try:
     35        # This should work for MySQL 5.0.
     36        cursor.execute("""
     37            SELECT column_name, referenced_table_name, referenced_column_name
     38            FROM information_schema.key_column_usage
     39            WHERE table_name = %s
     40                AND referenced_table_name IS NOT NULL
     41                AND referenced_column_name IS NOT NULL""", [table_name])
     42        constraints.extend(cursor.fetchall())
     43    except (ProgrammingError, OperationalError):
     44        # Fall back to "SHOW CREATE TABLE", for previous MySQL versions.
     45        # Go through all constraints and save the equal matches.
     46        cursor.execute("SHOW CREATE TABLE %s" % table_name)
     47        for row in cursor.fetchall():
     48            pos = 0
     49            while True:
     50                match = foreign_key_re.search(row[1], pos)
     51                if match == None:
     52                    break
     53                pos = match.end()
     54                constraints.append(match.groups())
    1755
     56    # handle constraints. (can't do this in the loop above since we need the cursor in both places)
     57    for my_fieldname, other_table, other_field in constraints:
     58        other_field_index = _name_to_index(cursor, other_table)[other_field]
     59        my_field_index = my_field_dict[my_fieldname]
     60        relations[my_field_index] = (other_field_index, other_table)
     61    return relations
     62
    1863def get_indexes(cursor, table_name):
    1964    """
    2065    Returns a dictionary of fieldname -> infodict for the given table,
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