What if I don't want $partial("templates/post-list.html")$ to be in index.html?

[HenryDashwood]

This is probably quite an obvious question so apologies in advance.

Suppose I'm working with the example site and I decide I would like the the list of posts to be generated in a template. If I move the the line $partial("templates/post-list.html")$ into, say, templates/default.html so the header there now looks like this:

    <header>
      <div class="logo">
        <a href="/">My Hakyll Blog</a>
      </div>
      <nav>
        <a href="/">Home</a>
        <a href="/about.html">About</a>
        <a href="/contact.html">Contact</a>
        <a href="/archive.html">Archive</a>
      </nav>
      $partial("templates/post-list.html")$
    </header>

I'll get the following error when I try to rebuild the site

Removing _site...
Removing _cache...
Removing _cache/tmp...
Initialising...
  Creating store...
  Creating provider...
  Running rules...
Checking for out-of-date items
Compiling
  updated templates/default.html
  updated templates/post-list.html
  [ERROR] Hakyll.Web.Template.applyTemplate: Failed to apply template templates/default.html to item about.rst:
    In expr '$partial("templates/post-list.html")$',
    In inclusion of '$partial("templates/post-list.html")$',
    Hakyll.Web.Template.applyTemplate: Failed to apply template templates/post-list.html to item about.rst:
    In expr '$for(posts)$',
    Tried field body,
    No 'posts' field in metadata of item about.rst,
    Tried field url,
    Tried field path,
    Tried field title,
    Missing field 'posts' in context

I'm a little stuck on what I do to resolve this. Any help much appreciated!

[pcoves]

Hi 👋

I'm new to hakyll and haskell but I'll try my best.

Hakyll tells you that, while compiling about.rst and applying the templates/default.html template, the posts field is missing.
As a matter of facts, if you simply moved $partial("templates/post-list.html")$ from index.html to templates/default.html, it's true.

You now have to make the posts field available any time you apply the templates/default.html template.
This (faulty) code does it : http://ix.io/2Dxg

But now, you're facing an issue : by default you apply templates/default.html template to every page, including the posts/* ones.
So, you're basically asking hakyll to use compilation of every posts in every posts, hence : [ERROR] Hakyll.Core.Runtime.chase: Dependency cycle detected: [...].

One solution would be to have two "default" templates, one in general and one for the posts.

---

In my humble opinion, you don't want your posts to be displayed in every single page of your site.
I mean, you can do it, but, should you really?

EDIT: your -> you're

[HenryDashwood]

Ah I see what you mean. I mean it's more a general question about how generating a list of things in a template. But yeah it seems like something that might be hard to implement. I'll put it on the back burner until I'm more adept with Ha[ske/k]ll. Thanks for your help!

[pcoves]

Well, it depends on what you really want.

Here, you try to generate a bunch of content base on your posts and I guess this page will help you understand how to deal with versions.

But yeah, generating listFields is not alway easy.
I took different pieces of code from various blogs and from hakyll's code for this one if you ever need it :

customListField :: String -> String -> Context a
customListField key custom = listFieldWith key (field custom $ return . itemBody) customListField'
    where
        customListField' :: Item b -> Compiler [Item String]
        customListField' item = do
            metadata <- getMetadata $ itemIdentifier item
            let customs = fromMaybe [] $
                    (lookupStringList key metadata) `mplus`
                    (map trim . splitAll "," <$> lookupString key metadata)
            mapM makeItem customs

This will look at an Item's metadata and create a listField base on its content.

For example adding customListField foo bar to a context will allow you to write :

$for(foo)$
    $bar$
$endfor$

So if you have

foo:
  - a
  - b
  - c

or

foo: a, b, c

The $foo$ listField will contain [a, b, c] in $bar$s.