Data Deep Merge New in v0.6.0 #
Opts in to a full deep merge when combining the Data Cascade. This will use something like lodash.mergewith to combine Arrays and deep merge Objects, rather than a simple top-level merge using Object.assign. Read more at Issue #147. This will likely become the default in an upcoming major version.
module.exports = function(eleventyConfig) {
  eleventyConfig.setDataDeepMerge(true);
};Note that all data stored in the pagination variable is exempted from this behavior (we don’t want pagination.items to be merged together).
Example #
---
title: This is a Good Blog Post
tags:
  - CSS
  - HTML
layout: my-layout.njk
eleventyNavigation:
  key: my-key
------
title: This is a Very Good Blog Post
author: Zach
tags:
  - JavaScript
eleventyNavigation:
  parent: test
---Without Deep Data Merge #
Results in the following data available in my-template.md:
{
  "title": "This is a Good Blog Post",
  "author": "Zach",
  "tags": [
    "CSS",
    "HTML"
  ],
  "eleventyNavigation": {
    "key": "my-key"
  }
}With Data Deep Merge #
With this enabled, your data structure will look like this when my-template.md is rendered:
{
  "title": "This is a Good Blog Post",
  "author": "Zach",
  "tags": [
    "CSS",
    "HTML",
    "JavaScript"
  ],
  "eleventyNavigation": {
    "key": "my-key",
    "parent": "test"
  }
}Using the override: prefix #
Use the override: prefix on any data key to opt-out of this merge behavior for specific values or nested values.
{
  "tags": ["posts"]
}---
override:tags: []
---Even though normally the posts/firstpost.md file would inherit the posts tag from the directory data file (per normal data cascade rules), we can override the tags value to be an empty array to opt-out of this behavior.

