@graphql-eslint/eslint-plugin/esm/rules/no-one-place-fragments.js

GraphQL plugin for ESLint

import { CWD, requireSiblingsOperations } from '../utils.js';
import { relative } from 'path';
import { visit } from 'graphql';
const RULE_ID = 'no-one-place-fragments';
export const rule = {
    meta: {
        type: 'suggestion',
        docs: {
            category: 'Operations',
            description: 'Disallow fragments that are used only in one place.',
            url: `https://github.com/B2o5T/graphql-eslint/blob/master/docs/rules/${RULE_ID}.md`,
            examples: [
                {
                    title: 'Incorrect',
                    code: /* GraphQL */ `
            fragment UserFields on User {
              id
            }

            {
              user {
                ...UserFields
              }
            }
          `,
                },
                {
                    title: 'Correct',
                    code: /* GraphQL */ `
            fragment UserFields on User {
              id
            }

            {
              user {
                ...UserFields
                friends {
                  ...UserFields
                }
              }
            }
          `,
                },
            ],
            requiresSiblings: true,
        },
        messages: {
            [RULE_ID]: 'Fragment `{{fragmentName}}` used only once. Inline him in "{{filePath}}".',
        },
        schema: [],
    },
    create(context) {
        const operations = requireSiblingsOperations(RULE_ID, context);
        const allDocuments = [...operations.getOperations(), ...operations.getFragments()];
        const usedFragmentsMap = Object.create(null);
        for (const { document, filePath } of allDocuments) {
            const relativeFilePath = relative(CWD, filePath);
            visit(document, {
                FragmentSpread({ name }) {
                    const spreadName = name.value;
                    usedFragmentsMap[spreadName] || (usedFragmentsMap[spreadName] = []);
                    usedFragmentsMap[spreadName].push(relativeFilePath);
                },
            });
        }
        return {
            'FragmentDefinition > Name'(node) {
                const fragmentName = node.value;
                const fragmentUsage = usedFragmentsMap[fragmentName];
                if (fragmentUsage.length === 1) {
                    context.report({
                        node,
                        messageId: RULE_ID,
                        data: { fragmentName, filePath: fragmentUsage[0] },
                    });
                }
            },
        };
    },
};