Set textarea value only when set.

[MattHolmes123]

Example below showing problem with govukTextarea rendering None when default is None

  <h3>Example govukInput with default value of None</h3>
  {{ govukInput({
      "label": {
        "text": "What is the name of the event?",
        "classes": "govuk-label--l",
        "isPageHeading": true
      },
      "id": "event-name",
      "name": "eventName",
      "value": None
    }) }}

  <h3>Example govukTextarea with default value of None</h3>
  {{ govukTextarea({
    "name": "moreDetail",
    "id": "more-detail",
    "label": {
      "text": "Can you provide more detail?",
      "classes": "govuk-label--l",
      "isPageHeading": true
    },
    "hint": {
      "text": "Do not include personal or financial information, like your National Insurance number or credit card details"
    },
    "value": None
  }) }}

[MattHolmes123]

Would you like me to update the vulnerability in this PR?

[matthew-shaw]

Hi @MattHolmes123 thanks for the contribution 🎉

Could you just omit passing the value key to the macro? It seems that for the textarea component this is coerced into a string, but not for the input component. This is consistent with the original GOV.UK Frontend component macro behaviour too, so while it could handle it more gracefully, it would deviate from the source material.

If you're creating and validating form field inputs, have you considered using GOV.UK Frontend WTForms?

[MattHolmes123]

Hi @matthew-shaw.

Thanks for the recommendation but I'm working with Django.
I will close this PR then as I understand the need to not deviate away from the source material.
I may even raise it as an issue in the original GOV.UK frontend project.

Great project btw it's helped my team loads. 👍

[MattHolmes123]

Hi @matthew-shaw
So I checked out the govuk-frontend project and tested it and the bug isn't found in their version.

I manually changed the template.njk file to this and it didn't render "null" in the text area:
{{- govukAttributes(params.attributes) }}>{{ null }}</textarea>

If you look at the Nunjucks docs for variables it does say "If a value is undefined or null, nothing is displayed".

So will leave it with you if you want this change or not.
Thanks 👍