Django：模板中的自定义标签和标签评估

Question

I wrote a custom tag named addattrs that allow me add HTML attributes easily.

I uses it that way:

<div>
  <label>Last name</label>
  {{ form.last_name|addattrs:"class=blue-form&placeholder=Please enter your name" }}
</div>

It works well. But now, I'd like to add the value attribute to HTML:

<div>
  <label>Last name</label>
  <!-- last_name is availaible from the current context -->
  {{ form.last_name|addattrs:"class=blue-form&value=last_name" }}
</div>

The problem is last_name is not evaluated and wrote as is in my form. How to force last_name to be evaluated? I tried a {% with last_name as myvariable %} block, but the result is exactly the same.

Thanks.

EDIT

The alecxe solution works. However, if the value is a datetime, it does not work anymore (no python Error but no attribute at all in the HTML.) I tried this:

{% with "class=blue-form&value="|add:birth_date as attrs %}
    {{ form.birth_date|addattrs:attrs }}
{% endwith %}

Answer 1

You can use add template filter :

{% with "class=blue-form&value="|add:last_name as attrs %}
    {{ form.last_name|addattrs:attrs }}
{% endwith %}

---

For the date value, you need to convert it to a string first. Either in the view, or in the template via date template filter , example:

{% with birth_date|date:"D d M Y" as my_date %}
    {% with "class=blue-form&value="|add:my_date as attrs %}
        {{ form.last_name|addattrs:attrs }}
    {% endwith %}
{% endwith %}