Show News Item creator or owner full name in Plone - plone

Question

I'm trying to show the full name for each news item in a list. For the moment I have only the user id (nickname).
Is there a simple way (in existing .pt file) to show the full name of creator or owner instead of a nickname?
The page must work for anonymous users, too. I mean - the page must be public.
Some details:
<div class="container-fluid news-list-container"
tal:define="news_items python:context.getFolderContents(contentFilter={'portal_type':['News Item'], 'sort_on': 'Date', 'sort_order': 'descending',});
Batch python:modules['Products.CMFPlone'].Batch;
b_size python:4;
b_start python:0;
b_start request/b_start | b_start;
batch python:Batch(news_items, b_size, int(b_start), orphan=0);"
tal:condition="news_items">
<div class="news-list-items">
<tal:items tal:repeat="news_item batch">
<!-- News item -->
<div class="row news-item"
tal:define="news_object python:news_item.getObject();
news_date python:news_object.getField('modification_date').getAccessor(news_object)();
news_title python:news_object.getField('title').getAccessor(news_object)();
news_description python:news_object.getField('description').getAccessor(news_object)();
news_image python:news_object.getField('image').getAccessor(news_object)();
news_url python:news_object.absolute_url();
news_creators python:news_object.getField('creators').getAccessor(news_object)(); .... ...

Answer 1

<tal:fullname define="membership context/portal_membership;
info python:membership.getMemberInfo(user.getId());
fullname info/fullname">
You are are <span class="name" tal:content="fullname" />
</tal:fullname>
This example is taken from the plone documentation

Answer 2

You can get inspired a lot by this code:
https://github.com/collective/Products.Scrawl/blob/1021047c4ef6c2655d104e8b345a24140da9e4aa/Products/Scrawl/browser/blogentry_view.pt#L32
<tal:name tal:condition="item_creator"
tal:define="author python:context.portal_membership.getMemberInfo(item_creator)">
<span i18n:translate="label_by_author">Posted by
<a href="#"
title="Read more posts by this author"
tal:attributes="href string:${context/portal_url}/author/${item_creator}"
tal:content="python:author and author['fullname'] or item_creator"
tal:omit-tag="not:author"
i18n:domain="scrawl"
i18n:name="author"
i18n:attributes="title author_title">
Bob Dobalina
</a>
</span>
</tal:name>
Mind the possible performance issues.
A cached view method may work a lot better, e.g.:
#memoize
def userid2fullname(self, userid):
pm = api.portal.get_tool('portal_membership')
memberinfo = pm.getMemberInfo(userid)
return memberinfo and memberinfo['fullname'] or userid