How to get custom title and description per page

This recipe shows you how to setup your application so you can customize title and description per page, while keeping a safe default for when it’s not specified.

The default values will be specified in your _harp.json file, and we’ll override those values per page using our _data.json file.

You can find more information about templates data on the docs.

Overview

Directory structure:

_harp.json
_data.json
index.jade  // or index.ejs
about.jade  // or about.ejs

For this example, this is the behaviour we want: if a visitor is requesting the index page we show the default values of title and description, when they request the about page, we show custom values.

Setup default values

First we’re going to specify our default values that will get used if the page doesn’t have specific values. In your _harp.json:

{
  "globals": {
    "title": "My default title",
    "description": "My default description"
  }
}

Setup custom values for about page

Now go to the _data.json file and add the custom values that you want for the about page:

{
  "about": {
    "title": "Welcome to my about page",
    "description": "I’m awesome and so are you"
  }
}

Use the values in your template

If you’re using Jade…

Now we’re going to use in our _layout.jade file the title and description that we just added to our _harp.json file.

doctype
html(lang="en")
  head
    title= title
    meta(name="description" content="#{ description })
  body
    != yield

If you’re using EJS…

If you’re using EJS, this is what your _layout.ejs should look like:

<!DOCTYPE html>
<html lang="en">
  <head>
    <title><%= title %></title>
    <meta name="description" content="<%= description %>" />
  </head>
  <body> <%- yield %> </body>
</html>

Results

Now when you visit the index page, Harp will render the default values specified in _harp.json.

When you visit the about page, Harp overrides the default title and description variables with the ones specified in the _data.json.

If you wanted to show custom values for the index page, you just need to add the index key to the _data.json, like this:

{
  "about": {
    "title": "Welcome to my about page",
    "description": "I’m awesome and so are you"
  },
  "index": {
    "title": "This is my home page",
    "description": "Best home page ever"
  }
}

Keep in mind that you don’t have to override the two variables. If you override only the title variable, the template will still use the default value for the description variable.

How does this work?

The values specified in the _harp.json globals are made available as template variables, so they can be used in any page at any time.

When a Harp tries to render a page, it tries to match the url path to data that is defined in _data.json. In this case, it’s matching the about part of the URL path with the about key in the _data.json file.

When Harp finds a match, it makes those variables available for the template that’s getting rendered. And in this case, it overrides the variables that we previously set in _harp.json.

You can find more information about templates data on the docs.