Overriding the Central `data.json` Values with Pattern specific Values

When setting up atoms, molecules, and organisms using the central data.json file for your data variables and values may work just fine. When fleshing out templates & pages, where data may need to be unique to each page but still use the same partials, the central data.json file can become very cumbersome. In order to work around this the PHP version of Pattern Lab allows you to define pattern-specific JSON files that allow you to override the default values.

Setting Up Pattern-specific Data

In order to tell the PHP version of Pattern Lab to use a pattern-specific JSON file to override the default variables just give the JSON file the same name as the pattern and put it in the same directory as the pattern. For example, if you wanted to provide pattern-specific data for the article pattern under the pattern type pages your pages directory would look like this:

pages/article.mustache
pages/article.json

Overriding the Default Variables

Overriding the default variables using the pattern-specific data is a just a matter of giving the variables you want to override the same names and structure in your pattern-specific data as they appear in the central data file. For example, the 4x3 landscape image source may look like this in data.json:

"landscape-4x3": {
    "src": "../../images/fpo-landscape-4x3.jpg",
    "alt": "Landscape 4x3 Image"
}

In our pattern-specific data file, article.json, we'd simply copy that structure and provide our own information:

"landscape-4x3": {
    "src": "../../images/a-team-hero.jpg"
}

Now the article pattern will display an image of the A-Team when using {{ landscape-4x3.src }}. All other patterns using {{ landscape-4x3.src }} will display the default 4x3 image. Also, note that we didn't override the landscape-4x3.alt attribute. If we were to use that attribute in our pattern the default value, "Landscape 4x3 Image", would be displayed.

Important note: You don't have to override every attribute. You can limit the data in your pattern-specific data file to just those variables you want. The PHP version of Pattern Lab will fallback to using the default attributes from data.json if the attributes aren't defined in the pattern-specific data file.

Working With Partials

Pattern-specific data is only loaded for the overall pattern and not for any related partials. For example, the pages template, article, might include the molecule, block-hero. block-hero may have its own pattern-specific data file, block-hero.json. The PHP version of Pattern Lab will not use the block-hero data when rendering article. It will only use article.json (if available) and data.json.