[Sqlalchemy-tickets] Issue #4220: Wrong `bindparam()` call signature in "Specifying Bound Parameter Behaviors" (zzzeek/sqlalchemy)

[Ilja E. <iss...@bi...>]

New issue 4220: Wrong `bindparam()` call signature in "Specifying Bound Parameter Behaviors"
https://bitbucket.org/zzzeek/sqlalchemy/issues/4220/wrong-bindparam-call-signature-in

Ilja Everilä:

In ["Specifying Bound Parameter Behaviors"](http://docs.sqlalchemy.org/en/latest/core/tutorial.html#specifying-bound-parameter-behaviors) there is:

> The parameters can also be explicitly typed:
>
>     stmt = stmt.bindparams(bindparam("x", String), bindparam("y", String))

but the call signature of [`bindparam()`](http://docs.sqlalchemy.org/en/latest/core/sqlelement.html#sqlalchemy.sql.expression.bindparam) is:

    sqlalchemy.sql.expression.bindparam(key, value=symbol('NO_ARG'), type_=None, ...)

Hence the example in the documentation would end up passing the type as the `value` argument. The error is not apparent given the example from the documentation, since the values are overridden when executing the statement, but will become apparent, if not:

```
#!python

>>> stmt = text("SELECT * FROM users WHERE users.name BETWEEN :x AND :y")
>>> stmt = stmt.bindparams(bindparam("x", String), bindparam("y", String))
>>> result = conn.execute(stmt)
Traceback (most recent call last):
  File "/home/saarni/Work/sqlalchemy/lib/sqlalchemy/engine/base.py", line 1193, in _execute_context
    context)
  File "/home/saarni/Work/sqlalchemy/lib/sqlalchemy/engine/default.py", line 507, in do_execute
    cursor.execute(statement, parameters)
sqlite3.InterfaceError: Error binding parameter 0 - probably unsupported type.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/saarni/Work/sqlalchemy/lib/sqlalchemy/engine/base.py", line 948, in execute
    return meth(self, multiparams, params)
  File "/home/saarni/Work/sqlalchemy/lib/sqlalchemy/sql/elements.py", line 269, in _execute_on_connection
    return connection._execute_clauseelement(self, multiparams, params)
  File "/home/saarni/Work/sqlalchemy/lib/sqlalchemy/engine/base.py", line 1060, in _execute_clauseelement
    compiled_sql, distilled_params
  File "/home/saarni/Work/sqlalchemy/lib/sqlalchemy/engine/base.py", line 1200, in _execute_context
    context)
  File "/home/saarni/Work/sqlalchemy/lib/sqlalchemy/engine/base.py", line 1413, in _handle_dbapi_exception
    exc_info
  File "/home/saarni/Work/sqlalchemy/lib/sqlalchemy/util/compat.py", line 203, in raise_from_cause
    reraise(type(exception), exception, tb=exc_tb, cause=cause)
  File "/home/saarni/Work/sqlalchemy/lib/sqlalchemy/util/compat.py", line 186, in reraise
    raise value.with_traceback(tb)
  File "/home/saarni/Work/sqlalchemy/lib/sqlalchemy/engine/base.py", line 1193, in _execute_context
    context)
  File "/home/saarni/Work/sqlalchemy/lib/sqlalchemy/engine/default.py", line 507, in do_execute
    cursor.execute(statement, parameters)
sqlalchemy.exc.InterfaceError: (sqlite3.InterfaceError) Error binding parameter 0 - probably unsupported type. [SQL: 'SELECT * FROM users WHERE users.name BETWEEN ? AND ?'] [parameters: (<class 'sqlalchemy.sql.sqltypes.String'>, <class 'sqlalchemy.sql.sqltypes.String'>)] (Background on this error at: http://sqlalche.me/e/rvf5)
```

The example should be:

    stmt = stmt.bindparams(bindparam("x", type_=String), bindparam("y", type_=String))