如何使用 Twig 的属性函数访问嵌套对象属性

Question

I'm trying to use a twig variable to access attributes of another twig variable which was not working until I found the "attributes" function. Works well except in the cases where I need to access nested attributes. It doesn't work when the variable containing the attribute is actually an object + attribute. For example:

{{ attribute(object1, variable) }} where variable = name, works just fine. {{ attribute(object1, variable) }} where variable = object2.name, doesn't work. However, a hard coded test of {{ object1.object2.name }} does work.

Here's how I got to this point...I have a yaml config file that gets parsed by the controller and passes it to twig in an array named 'config'. It contains parameters to define what gets displayed by the twig template.

fields:
  - name: company.name
    label: 'ODM'
    indexView: true
    recodrdView: true
  - name: location
    label: 'Location'
    indexView: true
    recordView: true

Additionally, an array of objects (entities) gets passed to the template for rendering.

The above "fields.name" is the name of the entity property. I iterate over the array of entities and then iterate over the config.fields array to determine what to display. Here's the twig code:

{% for data in datum %}
    <tr>
    {% for field in config.fields %}
        {% if field.indexView %}
            <td>{{ attribute(data, field.name }}</td>       
        {% endif %}
    {% endfor %}
    </tr>
{% endfor %}

I get the error:

Neither the property "company.name" nor one of the methods "company.name()", "getcompany.name()"/"iscompany.name()"/"hascompany.name()" or "__call()" exist and have public access in class "App\Entity\Odm".

I suppose I could split up the field.name string with a '.' delimiter and then make the necessary number of calls to attribute, but I'm really hoping there's a more eloquent solution. I've also tried _context['data.' ~ field.name] - no luck there either.

Any ideas?

Answer 1

Just think about the naming of the attributes: is a single attribute called company.name , then you can access it this way. If there is an attribute company which itself holds another attribute called name , then you cannot access it using company.name .

What you could try instead: write a twig macro that uses your field name, splits it a the dot and recursively calls itself if the remaining part still contains a dot.

Answer 2

You should nest your calls to attribute .

Eg to get the same functionality as object1.object2.name you would use:

{{ attribute(attribute(object1, 'object2'), 'name') }}

Answer 3

To expand on Nico 's answer

You could achieve this with the following snippet:

main.twig

{% import 'macro.twig' as macro %}
{{ macro.get_attribute(foo, 'bar.foobar') }}

macro.twig

{% macro get_attribute(object, attributes) %}
    {% apply spaceless %}
    {% set attributes = attributes|split('.') %}

    {% set value = object %}
    {% for attribute in attributes %}
        {% set value = attribute(value, attribute|trim) is defined ? attribute(value, attribute|trim) : null %}
    {% endfor %}
    {{ value }}
    {% endapply %}    
{% endmacro %}

demo

---

However a side note, if you are trying to use a macro for this and store the "output" in a variable, keep in mind that a macro will return an instance of Twig_Markup . This means you can't use the value later on.

An example:

data

foo:
    bar:
        foobar: 'Lorem Lipsum'

main.twig

{% set bar = macro.get_attribute(foo, 'bar') %}
{{ bar.foobar }} {# <--- error cause `foobar` is not a member of `Twig_Markup` #}

The real value of bar actually is not even an object or array, but just a string with, in this example, Array as content

{% set bar = macro.get_attribute(foo, 'bar') %}
{{ bar }} {# output: Array #}

Answer 4

如果您使用的是 Twig >= 2.10，则可以使用reduce()过滤器：

{{ field.name|split('.')|reduce((carry, v) => carry ? attribute(carry, v) : null, data) }}