Canonical issue in header request link

[mateoamilia]

Hi, I have an issue matching my canonical url in the head and the canonical link in the header request.

I use a custom field in my entries for my canonical URL entry.canonicalLink Its just a basic text field, where if my authors need to put a canonical, they paste it in there.

An SEO consultant pointed out that the canonical in the I am injecting this NOT by using the hook method, but instead a simple twig method like so:

I need a way to customize the header canonical URL with my custom field.
I tried to add this in the head, but does not work.

{# Canonical to be added by SEO plugin into http headers #}
{% if entry is defined and entry.canonicalLink|length %}
{% set seo = craft.seo.custom({ canonical: entry.canonicalLink }) %}
{% endif %}

If not, perhaps you know a way to disable the automatic injecting of the header canonical?

If anyone has an idea on how to make this work. I'd very much appreciate this.
Thanks!

[mateoamilia]

Perhaps you can add a field in the settings to ask the user of the plugin, whether they want to overwrite http headers with a canonical, or whether they has a canonical field of their own to use instead?

Another recommendation for adding flexibility to this plugin would be to add a setting for both sitemaps and redirects. I just recently downloaded retour for redirects, but I'd like to keep using this plugin for sitemaps, I think it does a good job for sitemaps.

To fix my issue temporarly, I need to delete this code from my live site, but I dont know how to edit the vendor files in my production site.

seo/src/services/SeoService.php

    public function injectCanonical ()
    {
        list($field) = $this->_getElementAndSeoFields();

        Craft::$app->getResponse()->getHeaders()->add(
            'Link',
            '<' . $field->canonical . '>; rel="canonical"'
        );
    }

public function injectCanonical ()
{
    list($field, $element) = $this->_getElementAndSeoFields();

    // Use your custom field if defined
    if (isset($element->canonicalLink) && $element->canonicalLink) {
        $canonical = $element->canonicalLink;
    } else {
        $canonical = $field->canonical;
    }

    if (!empty($canonical)) {
        Craft::$app->getResponse()->getHeaders()->add(
            'Link',
            "<{$canonical}>; rel=\"canonical\""
        );
    }
}