Merge key

A data file uses <<, YAML’s merge key, to copy fields into an item from elsewhere in the file.

What you’ll see

error  Merge key: Statac doesn't copy fields in with `<<`
  Write the fields out in full.
  More: https://statac.dev/e/merge-key/

In the terminal the message also names the file and line where there is one, and marks the exact text.

Why Statac stops

Statac reads a data file exactly as it stands, so what you see in the file is what templates get. The merge key isn’t part of YAML’s current version, and readers disagree about it: some copy the fields in, others read << as a field of its own. Statac won’t guess which you meant.

How to fix it

Write the fields out in full in each item that has them. To keep a field called <<, put it in quotes: "<<":.

Example

data/people.yaml:

- &first
  name: Person 1
  role: Role 1
- <<: *first
  name: Person 2

Written out in full:

- name: Person 1
  role: Role 1
- name: Person 2
  role: Role 1

Its name

Name	merge-key
In the terminal	statac explain merge-key
To stop showing it	It stops the build, so it can't be quietened.