Twig: Is Twig using arrays directly or a copy of them, internally?

Created on 21 Jun 2017 · 7Comments · Source: twigphp/Twig

Hey, i am wondering about how Twig works with given arrays or array-like objects internally?

My current situation is, that i have instances of the class DataBlank, which purpose is to help with RDF data.

How this class works in a nutshell: If you access data via $foo['bar'], it checks first locally, if data is available, and if not, it asks the database. That dynamic behavior allows chains like $foo['bar']['baz']['booms'].

If i want to use foo['bar']['baz']['booms'] in Twig, it complains with

Key "backmodel:page-path" in object with ArrayAccess of 
class "Knorke\DataBlank" does not exist.

Here is the related code snippet:

{% for value in startpage_values %}
    {# check for according usersetting #}
    {% if value['backmodel:page-path'] == user['backmodel:has-user-settings']['backmodel:setting-startpage'] %}
        <option value="{{ value['backmodel:page-path'] }}" selected>{{ value['rdfs:label'] }}</option>
    {% else %}
        <option value="{{ value['backmodel:page-path'] }}">{{ value['rdfs:label'] }}</option>
    {% endif %}
{% endfor %}

Variable startpage_values is an instance of DataBlank as well as user.

The funny thing is, if i call $foo['bar']['baz']['booms'] first in PHP and use it later in Twig, the error disappears. So my guess is, that Twig uses a real array, like a copy of the original one, doesn't it?

Source

k00ni

Most helpful comment

yes Twig checks first, because it is the only way it can complain about it. and this is also necessary for the . operator, which allows accessing through different ways depending of what is available: https://twig.sensiolabs.org/doc/2.x/templates.html#variables

and yes, you could close the issue (I cannot as I don't have write access to the repo)

stof on 21 Jun 2017

👍2

All 7 comments

this is because your offsetExists implementation returns true only when the data is loaded already. so when Twig asks your object whether the key exists or no, the answer depends on whether you already loaded it before or no.

stof on 21 Jun 2017

👍1

The issue is in your own code. Your array-like may be happy with accessing keys that it itself reported as non-existent. We won't alter Twig to support this case (the only way is to delete any existence check in Twig, and this is not possible)

stof on 21 Jun 2017

Ah thanks, great hint! That fact i didn't expect. So, to be clear, Twig first checks if a key is available, before using it or complaining about it? Thanks.

k00ni on 21 Jun 2017