From 03c00b6375c5977d83e3e30c662ef2d93ac6f18a Mon Sep 17 00:00:00 2001
From: Trivikram Kamat <16024985+trivikr@users.noreply.github.com>
Date: Fri, 22 Mar 2024 09:15:38 -0700
Subject: [PATCH] Add an empty param if value is not passed for optional params
 in callback (#806)

---
 .changeset/odd-insects-learn.md               |  5 +++
 .../__fixtures__/misc/api-callback.input.js   |  2 +-
 .../apis/addEmptyObjectForUndefined.ts        | 33 +++++++++++++++++++
 src/transforms/v2-to-v3/apis/index.ts         |  1 +
 src/transforms/v2-to-v3/transformer.ts        |  2 ++
 5 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/odd-insects-learn.md
 create mode 100644 src/transforms/v2-to-v3/apis/addEmptyObjectForUndefined.ts

diff --git a/.changeset/odd-insects-learn.md b/.changeset/odd-insects-learn.md
new file mode 100644
index 000000000..1eb6e2c62
--- /dev/null
+++ b/.changeset/odd-insects-learn.md
@@ -0,0 +1,5 @@
+---
+"aws-sdk-js-codemod": patch
+---
+
+Add an empty param if value is not passed for optional params in callback
diff --git a/src/transforms/v2-to-v3/__fixtures__/misc/api-callback.input.js b/src/transforms/v2-to-v3/__fixtures__/misc/api-callback.input.js
index d6bf0d50a..24d66150f 100644
--- a/src/transforms/v2-to-v3/__fixtures__/misc/api-callback.input.js
+++ b/src/transforms/v2-to-v3/__fixtures__/misc/api-callback.input.js
@@ -2,7 +2,7 @@ import AWS from "aws-sdk";
 
 const client = new AWS.DynamoDB();
 
-client.listTables({}, (err, data) => {
+client.listTables((err, data) => {
   if (err) console.log(err, err.stack);
   else console.log(data);
 });
diff --git a/src/transforms/v2-to-v3/apis/addEmptyObjectForUndefined.ts b/src/transforms/v2-to-v3/apis/addEmptyObjectForUndefined.ts
new file mode 100644
index 000000000..ccf441494
--- /dev/null
+++ b/src/transforms/v2-to-v3/apis/addEmptyObjectForUndefined.ts
@@ -0,0 +1,33 @@
+import { Collection, JSCodeshift } from "jscodeshift";
+
+import { ClientIdentifier } from "../types";
+
+// Adds an empty object, if undefined is passed for optional parameters.
+export const addEmptyObjectForUndefined = (
+  j: JSCodeshift,
+  source: Collection<unknown>,
+  clientIdentifiers: ClientIdentifier[]
+): void => {
+  for (const clientId of clientIdentifiers) {
+    // Remove .promise() from client API calls.
+    source
+      .find(j.CallExpression, {
+        callee: {
+          type: "MemberExpression",
+          object: clientId,
+        },
+      })
+      .filter((callExpression) => {
+        return (
+          callExpression.value.arguments.length === 1 &&
+          ["FunctionExpression", "ArrowFunctionExpression"].includes(
+            callExpression.value.arguments[0].type
+          )
+        );
+      })
+      .replaceWith((callExpression) => {
+        callExpression.value.arguments.unshift(j.objectExpression([]));
+        return callExpression.value;
+      });
+  }
+};
diff --git a/src/transforms/v2-to-v3/apis/index.ts b/src/transforms/v2-to-v3/apis/index.ts
index 66f4874d2..a7d0b9974 100644
--- a/src/transforms/v2-to-v3/apis/index.ts
+++ b/src/transforms/v2-to-v3/apis/index.ts
@@ -1,3 +1,4 @@
+export * from "./addEmptyObjectForUndefined";
 export * from "./addNotSupportedComments";
 export * from "./addNotSupportedClientComments";
 export * from "./getClientWaiterStates";
diff --git a/src/transforms/v2-to-v3/transformer.ts b/src/transforms/v2-to-v3/transformer.ts
index 8d08536ae..c80fe0cce 100644
--- a/src/transforms/v2-to-v3/transformer.ts
+++ b/src/transforms/v2-to-v3/transformer.ts
@@ -10,6 +10,7 @@ import {
   getClientIdentifiersRecord,
   replaceAwsIdentity,
   replaceAwsError,
+  addEmptyObjectForUndefined,
 } from "./apis";
 import { replaceAwsUtilFunctions } from "./aws-util";
 import {
@@ -98,6 +99,7 @@ const transformer = async (file: FileInfo, api: API) => {
     }
 
     removePromiseCalls(j, source, clientIdentifiers);
+    addEmptyObjectForUndefined(j, source, clientIdentifiers);
 
     if (v2ClientName === S3) {
       replaceS3GetSignedUrlApi(j, source, clientIdentifiers);