More standard template filters

[Collin Anderson]

Hi All,

I use django templates a lot and I always wished there was a myvar|startswith:"teststring", myvar|endswith:"teststring" and a myvar|contains:"teststring" filter.

I instead do stuff like myvar|slice:":10" == "teststring" which is a total hack.

Is this something that could be simple and common enough to add to django as batteries-included built-in?

Thanks,

Collin

[Curtis Maloney]

On 4/5/19 3:06 AM, Collin Anderson wrote:
> Hi All,
>
> I use django templates a lot and I always wished there was a
> myvar|startswith:"teststring", myvar|endswith:"teststring" and a
> myvar|contains:"teststring" filter.

It's almost like we need a syntax for calling methods with an argument,
just like we can with filters.

For example (bring on the sheds for bikes!)

{{ myvar.startswith<"teststring" }}

> I instead do stuff like myvar|slice:":10" == "teststring" which is a
> total hack.
>
> Is this something that could be simple and common enough to add to
> django as batteries-included built-in?

Alternatively, I recall some time in the past I may have written a
"strings" template filter library simply to provide string methods as
filters...

--
Curtis

[Adam Johnson]

FYI Jinja2 allows (most) python expressions, so this would Just Work(TM):

{{  myvar.startswith("x") }}

Django Template Language has a lot of legacy that prevents this from happening, afaiu it would not be possible to move to it.

It's not hard to move your templates (asides from those extending external packages like the admin) to Jinja2, since the syntax is very similar and you can pop a Jinja2 backend in your TEMPLATES.

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Adam

[Curtis Maloney]

On 4/5/19 8:16 PM, Adam Johnson wrote:
> FYI Jinja2 allows (most) python expressions, so this would Just Work(TM):
>
> {{  myvar.startswith("x") }}
>
> Django Template Language has a lot of legacy that prevents this from
> happening, afaiu it would not be possible to move to it.

For "legacy" read "philosophical choices" :)

--
Curtis

[keshav kumar]

There are already filters which works on advance logic. for example :- 'join'. So, is it not good to add filter for startswith, endswith and contains as well? 

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Adam

[Collin Anderson]

I think it would be helpful to have builtin startswith, endswith and contains filters.

[keshav kumar]

So, can I create as a new feature and start working on it ?

[Fran Hrženjak]

A similar ticket from 6 years ago (with some more filters) was closed as a wontfix: https://code.djangoproject.com/ticket/22162

Unless there was a change in the phylosiphy, I don’t think this will be accepted either (I don’t have an opinion about whether it shouldbe, though leaning towards not).

As a side note, I think the `in` operator fills the function of the `contains` filter:

"testing" in myvar