Please explain __key in gatsby-source-filesystem

[don-esteban]

Hi,

Could someone explain or link to an explanation of __key used in gatsby-source-filesystem plugin?

I checked this documents

• https://www.gatsbyjs.com/docs/reference/config-files/gatsby-config/
• https://www.gatsbyjs.com/plugins/gatsby-source-filesystem/

 {
  resolve: "gatsby-source-filesystem",
  options: {
    name: "images",
    path: "./src/images/",
  },
  __key: "images",
},
{
  resolve: "gatsby-source-filesystem",
  options: {
    name: "pages",
    path: "./src/pages/",
  },
  __key: "pages",
}

Thanks

[charsboo]

@don-esteban

I only see this property when a plugin is installed via Gatsby Recipes (the gatsby new command uses Gatsby Recipes).

According to the Gatsby Recipes README, the key prop is a "string used to distinguish between multiple plugin instances."

[wardpeet]

Recipes uses it under the hood to make sure when changes happen it can still understand which plugin to edit. Think of it as a unique identifier for every plugin, if there are duplicates we still know which one to apply changes to. You can ignore it and even remove it after recipes is done.