How to use filter using where and .Site.Data?

support
1

Assuming our normal markdown pages have a is_featured field in the frontmatter, we can filter like this

{{ range where .Site.Pages ".Params.is_featured" true }}

… but how can you do the same with data pages? E.g. content stored in data/posts/my-post.yml.

I tried many combinations but couldn’t make it work. What’s the proper syntax?

{{ range where .Site.Data.posts ".Params.is_featured" true }}
2

Try:

range where .Site.Data.posts "is_featured" true
3

Thanks, but it doesn’t return anything I’m afraid. See here:

image
image2290×554 119 KB

I searched some more and found that the “Site.Data…” are technically maps — not arrays — which could explain why the where does not work… Pretty counter-intuitive, especially since range works fine. See:

Wouldn’t hugo want to support this feature? Maybe automagically map the maps into arrays when used together with where?

4

The method used to extract the desired data depends on the data structure, and there are an infinite number of possible structures. If you share a meaningful sample of your data, perhaps we can find a way to get what you need.

5

You’re right, my bad. Looks like so:

/data/spaces/test.yml

name: My title
is_featured: true
6

Assuming this directory structure:

data
└── spaces/
    ├── a.yaml
    ├── b.yaml
    └── c.yaml

You can get a better understanding of your data structure with:

<pre>{{ jsonify (dict "indent" "  ") site.Data }}</pre>

That renders this:

{
  "spaces": {
    "a": {
      "is_featured": true,
      "name": "a"
    },
    "b": {
      "is_featured": false,
      "name": "b"
    },
    "c": {
      "is_featured": true,
      "name": "c"
    }
  }
}

So to find the “names” that are “featured”…

{{ range site.Data.spaces }}
  {{ if .is_featured }}
    {{ .name }}
  {{ end }}
{{ end }}
7

Thanks so much for the detailed answer and nifty tip with jsonify.

The nested-if solution works. How would you get the length of “featured spaces” in your example? You’d have to iterate and append into a new array, correct?

Seems useful if hugo could support maps with range where directly. Less mental overhead if site.pages + site.data would parse the same way. Anyway, that’s a feature request.

8

They do parse the same way when they have the same top-level structure.

If you had created a single spaces.yaml file instead of separate files in a spaces directory:

- name: a
  is_featured: true
- name: b
  is_featured: false
- name: c
  is_featured: true

This:

<pre>{{ jsonify (dict "indent" "  ") site.Data }}</pre>

Produces this:

{
  "spaces": [
    {
      "is_featured": true,
      "name": "a"
    },
    {
      "is_featured": false,
      "name": "b"
    },
    {
      "is_featured": true,
      "name": "c"
    }
  ]
}

And then you can do this:

{{ range where site.Data.spaces "is_featured" true }}
  {{ .name }}
{{ end }}

Finally, if you have this structure:

data
└── spaces/
    ├── a.yaml
    ├── b.yaml
    └── c.yaml

and if the file names should not be part of the data structure, you can wrangle the array of nested maps into an array of maps with:

{{ $temp := slice }}
{{ range site.Data.spaces }}
  {{ $temp = $temp | append . }}
{{ end }}

That looks like this:

[
  {
    "is_featured": true,
    "name": "a"
  },
  {
    "is_featured": false,
    "name": "b"
  },
  {
    "is_featured": true,
    "name": "c"
  }
]

and then you can do:

{{ range where $temp "is_featured" true }}
  {{ .name }}
{{ end }}