Put field's value on ahref

Question

everyone.

i added a field in res.partner called x_link

x_link = fields.Char(String="Link")

i want to add a buttom in portal_sidebar, with href = " value of x_link " .

Every partner has his own link that refers to another website account for exemple x_link of partner 1 contains facebook/jack x_link of partner 2 contains Exemple/David ... etc

i tried :

<a class="btn btn-primary btn-block " t-attf-href = "{{o.res.partner.x_link}}" > My link</a>

and

<a class="btn btn-primary btn-block " t-attf-href = "{{partner.x_link}}" > My link</a>

and

<a class="btn btn-primary btn-block " t-attf-href = "{{res.partner.x_link}}" > My link</a>

and

<a class="btn btn-primary btn-block " t-attf-href = "{{o.res.partner_id.x_link}}" > My link</a>

and

<a class="btn btn-primary btn-block " t-attf-href = "{{partner_id.x_link}}" > My link</a>

and

<a class="btn btn-primary btn-block " t-attf-href = "{{res.partner_id.x_link}}" > My link</a>

but i get error and when i tried :

<a class="btn btn-primary btn-block " t-attf-href = "{{x_link}}" > My link</a> 

the page refresh but don't redirect me to the website that x_link contains Thanks for helping me