feat(req-param): migrate req-param to codemod.com

codemods/req-param/README.md

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+# Migrate legacy `req.param(name)`
+
+The `req.param(name)` helper that used to magically look up values from multiple places has been removed. This potentially confusing and dangerous method of retrieving form data has been removed. You will now need to specifically look for the submitted parameter name in the `req.params`, `req.body`, or `req.query` object.
+
+## Examples
+
+### Replacing `req.param('body')` and `req.param('query')`
+
+Replace `req.param('body')` with `req.body` and
+`req.param('query')` with `req.query`.
+
+```diff
+app.get('/', (req, res) => {
+  // Before
+- const reqBody = req.param('body');
+- const reqQuery = req.param('query');
+  // After
++ const reqBody = req.body;
++ const reqQuery = req.query;
+});
+```
+
+### Replacing `req.param('paramName')`
+
+Replace `req.param('paramName')` with `req.params.paramName`.
+
+```diff
+app.get('/user/:id', (req, res) => {
+  // Before
+- const userId = req.param('id');
+  // After
++ const userId = req.params.id;
+});
+```
+
+## References
+
+- [Migration of `req.param()`](https://expressjs.com/en/guide/migrating-5.html#req.param)

codemods/req-param/codemod.yaml

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+schema_version: "1.0"
+name: "@expressjs/req-param"
+version: "1.0.0"
+description:  Migrates usage of the legacy APIs `req.param(name)` to the current recommended approaches
+author: bjohansebas (Sebastian Beltran)
+license: MIT
+workflow: workflow.yaml
+category: migration
+
+targets:
+  languages:
+    - javascript
+    - typescript
+
+keywords:
+  - transformation
+  - migration
+  - express
+  - params
+
+registry:
+  access: public
+  visibility: public

codemods/req-param/package.json

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+{
+  "name": "@expressjs/req-param",
+  "private": true,
+  "version": "1.0.0",
+  "description": "Migrates usage of the legacy APIs `req.param(name)` to the current recommended approaches.",
+  "type": "module",
+  "scripts": {
+    "test": "npx codemod jssg test -l typescript ./src/workflow.ts ./"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/expressjs/codemod.git",
+    "directory": "codemods/req-param",
+    "bugs": "https://github.com/expressjs/codemod/issues"
+  },
+  "author": "bjohansebas (Sebastian Beltran)",
+  "license": "MIT",
+  "homepage": "https://github.com/expressjs/codemod/blob/main/codemods/req-param/README.md",
+  "devDependencies": {
+    "@codemod.com/jssg-types": "^1.3.1"
+  }
+}

codemods/req-param/src/workflow.ts

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+import type Js from '@codemod.com/jssg-types/src/langs/javascript'
+import type { Edit, SgNode, SgRoot } from '@codemod.com/jssg-types/src/main'
+
+function getStringLiteralValue(node: SgNode<Js>): string | null {
+  if (!node.is('string')) return null
+
+  const fragments = node.findAll({ rule: { kind: 'string_fragment' } })
+  if (fragments.length !== 1) return null
+  return fragments[0]?.text() ?? null
+}
+
+function findParentFunctionParameters(node: SgNode<Js>): SgNode<Js, 'formal_parameters'> | null {
+  let parent = node.parent()
+  while (parent) {
+    if (parent.is('formal_parameters')) return parent
+    parent = parent.parent()
+  }
+  return null
+}
+
+async function transform(root: SgRoot<Js>): Promise<string | null> {
+  const rootNode = root.root()
+
+  const nodes = rootNode.findAll({
+    rule: {
+      pattern: '$OBJ.$METHOD($ARG)',
+    },
+    constraints: {
+      METHOD: { regex: '^(param)$' },
+    },
+  })
+
+  const edits: Edit[] = []
+
+  for (const call of nodes) {
+    const arg = call.getMatch('ARG')
+    const obj = call.getMatch('OBJ')
+
+    if (!arg || !obj) continue
+    const objDef = obj.definition({ resolveExternal: false })
+    if (!objDef) continue
+
+    const isParameter = objDef.node.matches({
+      rule: { inside: { kind: 'formal_parameters', stopBy: 'end' } },
+    })
+    if (!isParameter) continue
+
+    const parameters = findParentFunctionParameters(objDef.node)
+    if (!parameters) continue
+    const firstParameter = parameters.find({ rule: { kind: 'identifier' } })
+
+    if (!firstParameter) continue
+    const requestName = firstParameter.text()
+
+    const argValue = getStringLiteralValue(arg)
+
+    if (argValue === 'body') {
+      edits.push(call.replace(`${requestName}.body`))
+    } else if (argValue === 'query') {
+      edits.push(call.replace(`${requestName}.query`))
+    } else if (argValue) {
+      edits.push(call.replace(`${requestName}.params.${argValue}`))
+    }
+  }
+
+  if (edits.length === 0) return null
+
+  return rootNode.commitEdits(edits)
+}
+
+export default transform

codemods/req-param/tests/expected/params.ts

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+import express from "express";
+
+const app = express();
+
+app.get("/", function (req, res) {
+  const reqBody = req.body;
+  const reqQuery = req.query;
+  const reqQueryTest = req.query.test;
+  const reqOther = req.params.other;
+  const reqOtherNested = req.params.other.nested;
+});
+
+app.get("/", function (request, response) {
+  const reqBody = request.body;
+  const reqQuery = request.query;
+  const reqQueryTest = request.query.test;
+  const reqOther = request.params.other;
+  const reqOtherNested = request.params.other.nested;
+});
+
+app.get("/", (req, res) => {
+  const reqBody = req.body;
+  const reqQuery = req.query;
+  const reqQueryTest = req.query.test;
+  const reqOther = req.params.other;
+  const reqOtherNested = req.params.other.nested;
+});
+
+app.get("/", (request, response) => {
+  const reqBody = request.body;
+  const reqQuery = request.query;
+  const reqQueryTest = request.query.test;
+  const reqOther = request.params.other;
+  const reqOtherNested = request.params.other.nested;
+});
+
+app.param(function () {
+    // my important logic
+})

codemods/req-param/tests/input/params.ts

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+import express from "express";
+
+const app = express();
+
+app.get("/", function (req, res) {
+  const reqBody = req.param('body');
+  const reqQuery = req.param('query');
+  const reqQueryTest = req.param('query').test;
+  const reqOther = req.param('other');
+  const reqOtherNested = req.param('other').nested;
+});
+
+app.get("/", function (request, response) {
+  const reqBody = request.param('body');
+  const reqQuery = request.param('query');
+  const reqQueryTest = request.param('query').test;
+  const reqOther = request.param('other');
+  const reqOtherNested = request.param('other').nested;
+});
+
+app.get("/", (req, res) => {
+  const reqBody = req.param('body');
+  const reqQuery = req.param('query');
+  const reqQueryTest = req.param('query').test;
+  const reqOther = req.param('other');
+  const reqOtherNested = req.param('other').nested;
+});
+
+app.get("/", (request, response) => {
+  const reqBody = request.param('body');
+  const reqQuery = request.param('query');
+  const reqQueryTest = request.param('query').test;
+  const reqOther = request.param('other');
+  const reqOtherNested = request.param('other').nested;
+});
+
+app.param(function () {
+    // my important logic
+})

codemods/req-param/workflow.yaml

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+# yaml-language-server: $schema=https://raw.githubusercontent.com/codemod-com/codemod/refs/heads/main/schemas/workflow.json
+
+version: "1"
+
+nodes:
+  - id: apply-transforms
+    name: Apply AST Transformations
+    type: automatic
+    runtime:
+      type: direct
+    steps:
+      - name: Migrates usage of the legacy APIs `req.param(name)` to the current recommended approaches
+        js-ast-grep:
+          js_file: src/workflow.ts
+          base_path: .
+          semantic_analysis: file
+          include:
+            - "**/*.cjs"
+            - "**/*.js"
+            - "**/*.jsx"
+            - "**/*.mjs"
+            - "**/*.cts"
+            - "**/*.mts"
+            - "**/*.ts"
+            - "**/*.tsx"
+          exclude:
+            - "**/node_modules/**"
+          language: typescript