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no-private

Prevent importing private elements of another element.

Rule Details​

This rule enforces privacy boundaries between nested elements based on the following principles:

  • An element becomes private when it is nested under another element
  • Private elements can only be imported by their parent element
  • Private elements can import public elements
  • Private elements can import sibling elements (elements with the same parent)
  • Private elements can import uncle elements (direct children of a common ancestor) when the allowUncles option is enabled
info

This rule helps maintain encapsulation by preventing external elements from directly accessing the internal structure of other elements.

Options​

"boundaries/no-private":
  [<enabled>, { "allowUncles": <boolean>, "message": <string> }]

Configuration properties:

  • enabled: Enables the rule. 0 = off, 1 = warning, 2 = error
  • allowUncles: Optional. When set to false, disallows importing uncle elements. Default is true
  • message: Custom error message for rule violations. Note that the default message provides detailed information about why the error occurred, so only define a custom message if necessary. See error messages for more information

Configuration Example​

{
  "rules": {
    "boundaries/no-private": [2, { "allowUncles": true }]
  }
}

Settings​

The following examples use this project structure and settings configuration.

Project structure:

src/
└── modules/
    ├── module-a/
    │   ├── index.js
    │   └── ModuleA.js
    └── module-b/
        ├── index.js
        ├── ModuleB.js
        └── modules/
            ├── module-c/
            │   ├── index.js
            │   ├── ModuleC.js
            │   └── modules/
            │       └── module-e/
            │           ├── index.js
            │           └── ModuleE.js
            └── module-d/
                ├── index.js
                └── ModuleD.js

Settings configuration:

{
  "settings": {
    "boundaries/elements": [
      {
        "type": "modules",
        "pattern": "modules/*",
        "mode": "folder"
      }
    ],
  }
}
note

Some examples use aliases for the src/modules folder. You can also use relative paths, or you can configure the plugin to recognize aliases by using resolvers.

Examples​

Incorrect​

module-a importing module-c (private child of module-b):

// src/modules/module-a/ModuleA.js
import ModuleC from 'modules/module-b/modules/module-c'

module-b importing module-e (private grandchild):

// src/modules/module-b/ModuleB.js
import ModuleE from './modules/module-c/modules/module-e'

module-e importing module-d when allowUncles is disabled:

// src/modules/module-b/modules/module-c/modules/module-e/ModuleE.js
import ModuleD from 'modules/module-b/modules/module-d'

Correct​

module-b importing module-c (its direct child):

// src/modules/module-b/ModuleB.js
import ModuleC from './modules/module-c'

module-c importing module-a (public element):

// src/modules/module-b/modules/module-c/ModuleC.js
import ModuleA from 'modules/module-a'

module-c importing module-d (sibling element):

// src/modules/module-b/modules/module-c/ModuleC.js
import ModuleD from '../module-d'

module-e importing module-d (uncle element):

// src/modules/module-b/modules/module-c/modules/module-e/ModuleE.js
import ModuleD from 'modules/module-b/modules/module-d'

Error Messages​

This rule provides detailed error messages indicating which element owns the private element being imported.

Example message:

Dependency is private of element of type 'modules' with elementName 'module-b'

tip

You can customize error messages globally or for specific rules. See Rules Configuration for details.

Further Reading​

Read next sections to learn more about related topics: