CODEWITHSUNDEEP
pythondjangostring-formatting
Utkarsh Agarwal
Utkarsh Agarwal

Reputation: 158

Django unable to handle % symbol in sql while using python's old style string formatting

I am using Django 2.0.5 and my (unchangable) legacy sqlite database has % symbol in a few column names.

CREATE TABLE tbl("name" text, "col1(%)" float);

When I use django model filters, the filter value is applied as a param to the sql string with % operator as:

'SELECT "col1(%)" from tbl where name LIKE "%s" ' % 'John%'

Django is unfortunately not escaping the % symbol(in the column name) in such a scenario and this is causing an error at the string formatting option.

Any suggestion on how to get around this?

EDIT: I think my question pertains to https://code.djangoproject.com/ticket/9055, the problem is only in Django debug mode.

Here is the traceback:

Traceback (most recent call last):
  File "C:\svn\br_sqlite\camp2\venv\lib\site-packages\django\core\handlers\exception.py", line 35, in inner
    response = get_response(request)
  File "C:\svn\br_sqlite\camp2\venv\lib\site-packages\django\core\handlers\base.py", line 128, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "C:\svn\br_sqlite\camp2\venv\lib\site-packages\django\core\handlers\base.py", line 126, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "C:\svn\br_sqlite\camp2\main\views.py", line 72, in showData
    qs = validateInput(model,batch,version)
  File "C:\svn\br_sqlite\camp2\main\views.py", line 36, in validateInput
    return qs if len(qs) > 0 else None
  File "C:\svn\br_sqlite\camp2\venv\lib\site-packages\django\db\models\query.py", line 254, in __len__
    self._fetch_all()
  File "C:\svn\br_sqlite\camp2\venv\lib\site-packages\django\db\models\query.py", line 1179, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "C:\svn\br_sqlite\camp2\venv\lib\site-packages\django\db\models\query.py", line 53, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
  File "C:\svn\br_sqlite\camp2\venv\lib\site-packages\django\db\models\sql\compiler.py", line 1066, in execute_sql
    cursor.execute(sql, params)
  File "C:\svn\br_sqlite\camp2\venv\lib\site-packages\django\db\backends\utils.py", line 104, in execute
    sql = self.db.ops.last_executed_query(self.cursor, sql, params)
  File "C:\svn\br_sqlite\camp2\venv\lib\site-packages\django\db\backends\sqlite3\operations.py", line 143, in last_executed_query
    print(sql % params)
ValueError: unsupported format character ')' (0x29) at index 3252

A sample model:

class tbl(models.Model):
    name=models.TextField()
    col1=models.TextField(db_column="col1(%)")

and a view:

def test(request):
    a = tbl.objects.filter(name__contains='ab')
    return ""

Upvotes: 1

Views: 94

Answers (1)

dmoreno
dmoreno

Reputation: 706

Try using

'SELECT "col1(%%)" from tbl where name LIKE "%s" ' % 'John%'

Double %% is escaped to a single one.

Upvotes: 1

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