On May 16, 2013, at 6:22 PM, Bobby Impollonia <bob...@gmail.com> wrote:
> Sounds like a useful feature.
>
> Regarding case sensitivity, perhaps it would better if each of these methods
> (even like() and contains()) took a keyword argument along the lines of
> col.endswith('foo', case_sensitive=False) rather than adding extra methods
> with weird names like iendswith.
yes I've thought of that, though we already have "ilike()" for "like()", as
this is a well known Postgresql operator, so I fear this might introduce some
inconsistency. We'd really need to add "case_sensitive" to like() as well and
everywhere, and just have "ilike()" be a synonym for "like(...,
case_sensitive=False)".
Additionally, case_sensitive might need to default to "None" - in its absence,
technically we don't know if the underlying database is doing case sensitive
comparison or not. Setting it to "True" means, "we will use known
case-insensitive techniques for the target backend".
But then what do we do on a backend that doesn't have "ilike"? do we raise an
error? what if some backend already has case-insensitive collation set up ?
>
> On Monday, May 13, 2013 3:44:38 PM UTC-7, Michael Bayer wrote:
>
> On May 13, 2013, at 6:30 PM, Daniel Grace <thisgen...@gmail.com> wrote:
>
>> So today I identified a small bug in my code and then, while trying to
>> resolve it, came to a few realizations:
>>
>> 1. column.contains(str) does not escape characters in str such as % and _.
>> Presumably, column.startswith(str) and column.endswith(str) have the same
>> behavior.
>
> this will be called "autoescape" and is ticket 2694:
> http://www.sqlalchemy.org/trac/ticket/2694 . if someone wants to work on a
> patch for this it would be v. helpful. It's a little late to turn on the
> escaping for all users now as it would break existing workarounds.
>
>
>>
>> 2. There is a distinct lack of column.icontains(str), though the current
>> implementation means it's identical to column.ilike('%' + str + '%')
>
> since we do have "ilike()" as an operator "icontains()" would be appropriate
> at this point (also startswith,endswith).
>
>
>>
>> 3. There is no builtin function (that I found, please correct me if I'm
>> wrong!) for escaping a string being passed to any functions in this family.
>
> will be 2694
>
>>
>> While I think that column.like and column.ilike should definitely /not/
>> escape their argument (you know you're trying for a pattern match here, and
>> that you're matching against a pattern), I think that the
>> .contains/.startswith/.endswith family of functions probably should perform
>> this escaping transparently. Between DBAPI 2.0, SQLAlchemy and
>> parameterized querying I don't need to worry about escaping input, so why
>> should I have to pay attention to that detail when using .contains? Also,
>> case insensitive versions of the above would probably be useful.
>>
>> That said, a proper fix might be complicated since it could inadvertently
>> break existing code that relies on the current behavior of .contains()
>
>>
>> -- Daniel
>>
>>
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>
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