From f4ab3d067b0a7c70ba96ad827be4efaa5d0eb485 Mon Sep 17 00:00:00 2001
From: Andrea Amorosi <dreamorosi@gmail.com>
Date: Tue, 28 Mar 2023 20:28:08 +0200
Subject: [PATCH 1/5] feat: stronger types for SSM getParameter

---
 packages/parameters/src/ssm/SSMProvider.ts   | 14 +++++-----
 packages/parameters/src/ssm/getParameter.ts  | 14 ++++++----
 packages/parameters/src/types/SSMProvider.ts | 27 ++++++++++++++++++--
 3 files changed, 42 insertions(+), 13 deletions(-)

diff --git a/packages/parameters/src/ssm/SSMProvider.ts b/packages/parameters/src/ssm/SSMProvider.ts
index 14fd6793c2..d13abf8a5c 100644
--- a/packages/parameters/src/ssm/SSMProvider.ts
+++ b/packages/parameters/src/ssm/SSMProvider.ts
@@ -16,7 +16,9 @@ import type {
 import type {
   SSMProviderOptions,
   SSMGetMultipleOptionsInterface,
-  SSMGetOptionsInterface,
+  SSMGetOptions,
+  SSMGetOptionsUnion,
+  SSMGetOutput,
   SSMGetParametersByNameOutputInterface,
   SSMGetParametersByNameOptionsInterface,
   SSMSplitBatchAndDecryptParametersOutputType,
@@ -315,11 +317,11 @@ class SSMProvider extends BaseProvider {
    * @param {SSMGetOptionsInterface} options - Options to configure the provider
    * @see https://awslabs.github.io/aws-lambda-powertools-typescript/latest/utilities/parameters/
    */
-  public async get(
+  public async get<O extends SSMGetOptionsUnion | undefined = undefined>(
     name: string,
-    options?: SSMGetOptionsInterface | undefined
-  ): Promise<string | Record<string, unknown> | undefined> {
-    return super.get(name, options) as Promise<string | Record<string, unknown> | undefined>;
+    options?: O & SSMGetOptions
+  ): Promise<SSMGetOutput<O> | undefined> {
+    return super.get(name, options) as Promise<SSMGetOutput<O> | undefined>;
   }
 
   /**
@@ -471,7 +473,7 @@ class SSMProvider extends BaseProvider {
    */
   protected async _get(
     name: string,
-    options?: SSMGetOptionsInterface
+    options?: SSMGetOptions
   ): Promise<string | undefined> {
     const sdkOptions: GetParameterCommandInput = {
       ...(options?.sdkOptions || {}),
diff --git a/packages/parameters/src/ssm/getParameter.ts b/packages/parameters/src/ssm/getParameter.ts
index 12b09e0c08..f15e022bb1 100644
--- a/packages/parameters/src/ssm/getParameter.ts
+++ b/packages/parameters/src/ssm/getParameter.ts
@@ -1,5 +1,9 @@
 import { SSMProvider, DEFAULT_PROVIDERS } from './SSMProvider';
-import type { SSMGetOptionsInterface } from '../types/SSMProvider';
+import type {
+  SSMGetOptions,
+  SSMGetOptionsUnion,
+  SSMGetOutput,
+} from '../types/SSMProvider';
 
 /**
  * ## Intro
@@ -136,15 +140,15 @@ import type { SSMGetOptionsInterface } from '../types/SSMProvider';
  * @param {SSMGetOptionsInterface} options - Options to configure the provider
  * @see https://awslabs.github.io/aws-lambda-powertools-typescript/latest/utilities/parameters/
  */
-const getParameter = (
+const getParameter = <O extends SSMGetOptionsUnion | undefined = undefined>(
   name: string,
-  options?: SSMGetOptionsInterface
-): Promise<undefined | string | Record<string, unknown>> => {
+  options?: O & SSMGetOptions
+): Promise<SSMGetOutput<O> | undefined> => {
   if (!DEFAULT_PROVIDERS.hasOwnProperty('ssm')) {
     DEFAULT_PROVIDERS.ssm = new SSMProvider();
   }
 
-  return (DEFAULT_PROVIDERS.ssm as SSMProvider).get(name, options);
+  return (DEFAULT_PROVIDERS.ssm as SSMProvider).get(name, options) as Promise<SSMGetOutput<O> | undefined>;
 };
 
 export {
diff --git a/packages/parameters/src/types/SSMProvider.ts b/packages/parameters/src/types/SSMProvider.ts
index 36d5f85cb3..2e55b63fd7 100644
--- a/packages/parameters/src/types/SSMProvider.ts
+++ b/packages/parameters/src/types/SSMProvider.ts
@@ -54,11 +54,32 @@ type SSMProviderOptions = SSMProviderOptionsWithClientConfig | SSMProviderOption
  * @property {TransformOptions} transform - Transform to be applied, can be 'json' or 'binary'.
  * @property {boolean} decrypt - If true, the parameter will be decrypted.
  */
-interface SSMGetOptionsInterface extends GetOptionsInterface {
+interface SSMGetOptions extends GetOptionsInterface {
   decrypt?: boolean
   sdkOptions?: Partial<GetParameterCommandInput>
 }
 
+interface SSMGetOptionsTransformJson extends SSMGetOptions {
+  transform: 'json'
+}
+
+interface SSMGetOptionsTransformBinary extends SSMGetOptions {
+  transform: 'binary'
+}
+
+interface SSMGetOptionsTransformNone extends SSMGetOptions {
+  transform?: never
+}
+
+type SSMGetOptionsUnion = SSMGetOptionsTransformJson | SSMGetOptionsTransformBinary | SSMGetOptionsTransformNone | undefined;
+
+type SSMGetOutput<O = undefined> =
+    undefined extends O ? string :
+      O extends SSMGetOptionsTransformNone | SSMGetOptionsTransformBinary ? string :
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        O extends SSMGetOptionsTransformJson ? Record<string, any> :
+          never;
+
 /**
  * Options for the SSMProvider getMultiple method.
  *
@@ -121,7 +142,9 @@ type SSMGetParametersByNameFromCacheOutputType = {
 
 export type {
   SSMProviderOptions,
-  SSMGetOptionsInterface,
+  SSMGetOptions,
+  SSMGetOptionsUnion,
+  SSMGetOutput,
   SSMGetMultipleOptionsInterface,
   SSMGetParametersByNameOptionsInterface,
   SSMSplitBatchAndDecryptParametersOutputType,

From f18af60a0b9829e89ca1bfc0d3f31832e4ad9c23 Mon Sep 17 00:00:00 2001
From: Andrea Amorosi <dreamorosi@gmail.com>
Date: Wed, 29 Mar 2023 16:15:59 +0200
Subject: [PATCH 2/5] feat: improved types for getParameters

---
 packages/parameters/src/ssm/SSMProvider.ts   | 22 +++++----
 packages/parameters/src/ssm/getParameter.ts  |  6 ++-
 packages/parameters/src/ssm/getParameters.ts | 18 ++++---
 packages/parameters/src/types/SSMProvider.ts | 49 ++++++++++++++++++--
 4 files changed, 73 insertions(+), 22 deletions(-)

diff --git a/packages/parameters/src/ssm/SSMProvider.ts b/packages/parameters/src/ssm/SSMProvider.ts
index d13abf8a5c..c276e44f35 100644
--- a/packages/parameters/src/ssm/SSMProvider.ts
+++ b/packages/parameters/src/ssm/SSMProvider.ts
@@ -15,10 +15,12 @@ import type {
 } from '@aws-sdk/client-ssm';
 import type {
   SSMProviderOptions,
-  SSMGetMultipleOptionsInterface,
   SSMGetOptions,
   SSMGetOptionsUnion,
   SSMGetOutput,
+  SSMGetMultipleOptions,
+  SSMGetMultipleOptionsUnion,
+  SSMGetMultipleOutput,
   SSMGetParametersByNameOutputInterface,
   SSMGetParametersByNameOptionsInterface,
   SSMSplitBatchAndDecryptParametersOutputType,
@@ -314,7 +316,7 @@ class SSMProvider extends BaseProvider {
    * For usage examples check {@link SSMProvider}.
    *
    * @param {string} name - The name of the value to retrieve (i.e. the partition key)
-   * @param {SSMGetOptionsInterface} options - Options to configure the provider
+   * @param {SSMGetOptions} options - Options to configure the provider
    * @see https://awslabs.github.io/aws-lambda-powertools-typescript/latest/utilities/parameters/
    */
   public async get<O extends SSMGetOptionsUnion | undefined = undefined>(
@@ -351,14 +353,14 @@ class SSMProvider extends BaseProvider {
    * For usage examples check {@link SSMProvider}.
    *
    * @param {string} path - The path of the parameters to retrieve
-   * @param {SSMGetMultipleOptionsInterface} options - Options to configure the retrieval
+   * @param {SSMGetMultipleOptions} options - Options to configure the retrieval
    * @see https://awslabs.github.io/aws-lambda-powertools-typescript/latest/utilities/parameters/
    */
-  public async getMultiple(
+  public async getMultiple<O extends SSMGetMultipleOptionsUnion | undefined = undefined>(
     path: string,
-    options?: SSMGetMultipleOptionsInterface | undefined
-  ): Promise<undefined | Record<string, unknown>> {
-    return super.getMultiple(path, options);
+    options?: O & SSMGetMultipleOptions
+  ): Promise<SSMGetMultipleOutput<O> | undefined> {
+    return super.getMultiple(path, options) as Promise<SSMGetMultipleOutput<O> | undefined>;
   }
 
   /**
@@ -469,7 +471,7 @@ class SSMProvider extends BaseProvider {
    * Retrieve a parameter from AWS Systems Manager.
    *
    * @param {string} name - Name of the parameter to retrieve
-   * @param {SSMGetOptionsInterface} options - Options to customize the retrieval
+   * @param {SSMGetOptions} options - Options to customize the retrieval
    */
   protected async _get(
     name: string,
@@ -489,11 +491,11 @@ class SSMProvider extends BaseProvider {
    * Retrieve multiple items from AWS Systems Manager.
    *
    * @param {string} path - The path of the parameters to retrieve
-   * @param {SSMGetMultipleOptionsInterface} options - Options to configure the provider
+   * @param {SSMGetMultipleOptions} options - Options to configure the provider
    */
   protected async _getMultiple(
     path: string,
-    options?: SSMGetMultipleOptionsInterface
+    options?: SSMGetMultipleOptions
   ): Promise<Record<string, string | undefined>> {
     const sdkOptions: GetParametersByPathCommandInput = {
       ...(options?.sdkOptions || {}),
diff --git a/packages/parameters/src/ssm/getParameter.ts b/packages/parameters/src/ssm/getParameter.ts
index f15e022bb1..1769ebea2f 100644
--- a/packages/parameters/src/ssm/getParameter.ts
+++ b/packages/parameters/src/ssm/getParameter.ts
@@ -137,7 +137,7 @@ import type {
  * For more usage examples, see [our documentation](https://awslabs.github.io/aws-lambda-powertools-typescript/latest/utilities/parameters/).
  *
  * @param {string} name - The name of the parameter to retrieve
- * @param {SSMGetOptionsInterface} options - Options to configure the provider
+ * @param {SSMGetOptions} options - Options to configure the provider
  * @see https://awslabs.github.io/aws-lambda-powertools-typescript/latest/utilities/parameters/
  */
 const getParameter = <O extends SSMGetOptionsUnion | undefined = undefined>(
@@ -148,7 +148,9 @@ const getParameter = <O extends SSMGetOptionsUnion | undefined = undefined>(
     DEFAULT_PROVIDERS.ssm = new SSMProvider();
   }
 
-  return (DEFAULT_PROVIDERS.ssm as SSMProvider).get(name, options) as Promise<SSMGetOutput<O> | undefined>;
+  return (
+    DEFAULT_PROVIDERS.ssm as SSMProvider
+  ).get(name, options) as Promise<SSMGetOutput<O> | undefined>;
 };
 
 export {
diff --git a/packages/parameters/src/ssm/getParameters.ts b/packages/parameters/src/ssm/getParameters.ts
index e93daf1ea8..ede4f3e614 100644
--- a/packages/parameters/src/ssm/getParameters.ts
+++ b/packages/parameters/src/ssm/getParameters.ts
@@ -1,5 +1,9 @@
 import { SSMProvider, DEFAULT_PROVIDERS } from './SSMProvider';
-import type { SSMGetMultipleOptionsInterface } from '../types/SSMProvider';
+import type {
+  SSMGetMultipleOptions,
+  SSMGetMultipleOptionsUnion,
+  SSMGetMultipleOutput,
+} from '../types/SSMProvider';
 
 /**
  * ## Intro
@@ -134,18 +138,20 @@ import type { SSMGetMultipleOptionsInterface } from '../types/SSMProvider';
  * For more usage examples, see [our documentation](https://awslabs.github.io/aws-lambda-powertools-typescript/latest/utilities/parameters/).
  *
  * @param {string} path - The path of the parameters to retrieve
- * @param {SSMGetMultipleOptionsInterface} options - Options to configure the provider
+ * @param {SSMGetMultipleOptions} options - Options to configure the provider
  * @see https://awslabs.github.io/aws-lambda-powertools-typescript/latest/utilities/parameters/
  */
-const getParameters = (
+const getParameters = <O extends SSMGetMultipleOptionsUnion | undefined = undefined>(
   path: string,
-  options?: SSMGetMultipleOptionsInterface
-): Promise<undefined | Record<string, unknown>> => {
+  options?: O & SSMGetMultipleOptions
+): Promise<SSMGetMultipleOutput<O> | undefined> => {
   if (!DEFAULT_PROVIDERS.hasOwnProperty('ssm')) {
     DEFAULT_PROVIDERS.ssm = new SSMProvider();
   }
 
-  return (DEFAULT_PROVIDERS.ssm as SSMProvider).getMultiple(path, options);
+  return (
+    DEFAULT_PROVIDERS.ssm as SSMProvider
+  ).getMultiple(path, options) as Promise<SSMGetMultipleOutput<O> | undefined>;
 };
 
 export {
diff --git a/packages/parameters/src/types/SSMProvider.ts b/packages/parameters/src/types/SSMProvider.ts
index 2e55b63fd7..292ed5a828 100644
--- a/packages/parameters/src/types/SSMProvider.ts
+++ b/packages/parameters/src/types/SSMProvider.ts
@@ -50,12 +50,18 @@ type SSMProviderOptions = SSMProviderOptionsWithClientConfig | SSMProviderOption
  * @extends {GetOptionsInterface}
  * @property {number} maxAge - Maximum age of the value in the cache, in seconds.
  * @property {boolean} forceFetch - Force fetch the value from the parameter store, ignoring the cache.
- * @property {GetItemCommandInput} [sdkOptions] - Additional options to pass to the AWS SDK v3 client.
+ * @property {GetItemCommandInput} [sdkOptions] - Additional options to pass to the AWS SDK v3 client. Supports all options from `GetParameterCommandInput`.
  * @property {TransformOptions} transform - Transform to be applied, can be 'json' or 'binary'.
- * @property {boolean} decrypt - If true, the parameter will be decrypted.
+ * @property {boolean} decrypt - If true, the parameter will be decrypted. Defaults to `false`.
  */
 interface SSMGetOptions extends GetOptionsInterface {
+  /**
+   * If true, the parameter will be decrypted. Defaults to `false`.
+   */
   decrypt?: boolean
+  /**
+   * Additional options to pass to the AWS SDK v3 client. Supports all options from `GetParameterCommandInput`.
+   */
   sdkOptions?: Partial<GetParameterCommandInput>
 }
 
@@ -93,13 +99,46 @@ type SSMGetOutput<O = undefined> =
  * @property {boolean} recursive - If true, the parameter will be fetched recursively.
  * @property {boolean} throwOnTransformError - If true, the method will throw an error if the transform fails.
  */
-interface SSMGetMultipleOptionsInterface extends GetMultipleOptionsInterface {
+interface SSMGetMultipleOptions extends GetMultipleOptionsInterface {
+  /**
+   * Additional options to pass to the AWS SDK v3 client. Supports all options from `GetParametersByPathCommandInput`.
+   */
   sdkOptions?: Partial<GetParametersByPathCommandInput>
+  /**
+   * If true, the parameters will be decrypted. Defaults to `false`.
+   */
   decrypt?: boolean
+  /**
+   * If true, the parameters will be fetched recursively. Defaults to `false`.
+   */
   recursive?: boolean
+  /**
+   * If true, the method will throw an error if the transform fails.
+   */
   throwOnTransformError?: boolean
 }
 
+interface SSMGetMultipleOptionsTransformJson extends SSMGetMultipleOptions {
+  transform: 'json'
+}
+
+interface SSMGetMultipleOptionsTransformBinary extends SSMGetMultipleOptions {
+  transform: 'binary'
+}
+
+interface SSMGetMultipleOptionsTransformNone extends SSMGetMultipleOptions {
+  transform?: never
+}
+
+type SSMGetMultipleOptionsUnion = SSMGetMultipleOptionsTransformJson | SSMGetMultipleOptionsTransformBinary | SSMGetMultipleOptionsTransformNone | undefined;
+
+type SSMGetMultipleOutput<O = undefined> =
+    undefined extends O ? Record<string, string> :
+      O extends SSMGetMultipleOptionsTransformNone | SSMGetMultipleOptionsTransformBinary ? Record<string, string> :
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        O extends SSMGetMultipleOptionsTransformJson ? Record<string, Record<string, any>> :
+          never;
+
 /**
  * Options for the SSMProvider getParametersByName method.
  *
@@ -145,7 +184,9 @@ export type {
   SSMGetOptions,
   SSMGetOptionsUnion,
   SSMGetOutput,
-  SSMGetMultipleOptionsInterface,
+  SSMGetMultipleOptions,
+  SSMGetMultipleOptionsUnion,
+  SSMGetMultipleOutput,
   SSMGetParametersByNameOptionsInterface,
   SSMSplitBatchAndDecryptParametersOutputType,
   SSMGetParametersByNameOutputInterface,

From 971ce1af4a69765b5195fbdbde9bf910a5cda6a6 Mon Sep 17 00:00:00 2001
From: Andrea Amorosi <dreamorosi@gmail.com>
Date: Wed, 29 Mar 2023 23:14:20 +0200
Subject: [PATCH 3/5] feat: added explicit type override

---
 packages/parameters/src/ssm/SSMProvider.ts    | 20 ++++----
 packages/parameters/src/ssm/getParameter.ts   |  7 ++-
 packages/parameters/src/ssm/getParameters.ts  |  6 +--
 .../parameters/src/ssm/getParametersByName.ts | 11 +++--
 packages/parameters/src/types/BaseProvider.ts |  8 ++-
 packages/parameters/src/types/SSMProvider.ts  | 49 ++++++++++++++-----
 6 files changed, 65 insertions(+), 36 deletions(-)

diff --git a/packages/parameters/src/ssm/SSMProvider.ts b/packages/parameters/src/ssm/SSMProvider.ts
index c276e44f35..6d59f93fed 100644
--- a/packages/parameters/src/ssm/SSMProvider.ts
+++ b/packages/parameters/src/ssm/SSMProvider.ts
@@ -16,11 +16,11 @@ import type {
 import type {
   SSMProviderOptions,
   SSMGetOptions,
-  SSMGetOptionsUnion,
   SSMGetOutput,
   SSMGetMultipleOptions,
   SSMGetMultipleOptionsUnion,
   SSMGetMultipleOutput,
+  SSMGetParametersByNameOutput,
   SSMGetParametersByNameOutputInterface,
   SSMGetParametersByNameOptionsInterface,
   SSMSplitBatchAndDecryptParametersOutputType,
@@ -319,11 +319,11 @@ class SSMProvider extends BaseProvider {
    * @param {SSMGetOptions} options - Options to configure the provider
    * @see https://awslabs.github.io/aws-lambda-powertools-typescript/latest/utilities/parameters/
    */
-  public async get<O extends SSMGetOptionsUnion | undefined = undefined>(
+  public async get<T = undefined, O extends SSMGetOptions | undefined = SSMGetOptions>(
     name: string,
     options?: O & SSMGetOptions
-  ): Promise<SSMGetOutput<O> | undefined> {
-    return super.get(name, options) as Promise<SSMGetOutput<O> | undefined>;
+  ): Promise<SSMGetOutput<T, O> | undefined> {
+    return super.get(name, options) as Promise<SSMGetOutput<T, O> | undefined>;
   }
 
   /**
@@ -356,11 +356,11 @@ class SSMProvider extends BaseProvider {
    * @param {SSMGetMultipleOptions} options - Options to configure the retrieval
    * @see https://awslabs.github.io/aws-lambda-powertools-typescript/latest/utilities/parameters/
    */
-  public async getMultiple<O extends SSMGetMultipleOptionsUnion | undefined = undefined>(
+  public async getMultiple<T = undefined, O extends SSMGetMultipleOptionsUnion | undefined = undefined>(
     path: string,
     options?: O & SSMGetMultipleOptions
-  ): Promise<SSMGetMultipleOutput<O> | undefined> {
-    return super.getMultiple(path, options) as Promise<SSMGetMultipleOutput<O> | undefined>;
+  ): Promise<SSMGetMultipleOutput<T, O> | undefined> {
+    return super.getMultiple(path, options) as Promise<SSMGetMultipleOutput<T, O> | undefined>;
   }
 
   /**
@@ -413,10 +413,10 @@ class SSMProvider extends BaseProvider {
    * @param {SSMGetParametersByNameOptionsInterface} options - Options to configure the retrieval
    * @see https://awslabs.github.io/aws-lambda-powertools-typescript/latest/utilities/parameters/
    */
-  public async getParametersByName(
+  public async getParametersByName<T = undefined>(
     parameters: Record<string, SSMGetParametersByNameOptionsInterface>,
     options?: SSMGetParametersByNameOptionsInterface
-  ): Promise<Record<string, unknown>> {
+  ): Promise<SSMGetParametersByNameOutput<T>> {
     const configs = { ...{
       decrypt: this.resolveDecryptionConfigValue({}) || false,
       maxAge: DEFAULT_MAX_AGE_SECS,
@@ -464,7 +464,7 @@ class SSMProvider extends BaseProvider {
       }
     }
 
-    return response;
+    return response as unknown as Promise<SSMGetParametersByNameOutput<T>>;
   }
 
   /**
diff --git a/packages/parameters/src/ssm/getParameter.ts b/packages/parameters/src/ssm/getParameter.ts
index 1769ebea2f..9e61bc0c6a 100644
--- a/packages/parameters/src/ssm/getParameter.ts
+++ b/packages/parameters/src/ssm/getParameter.ts
@@ -1,7 +1,6 @@
 import { SSMProvider, DEFAULT_PROVIDERS } from './SSMProvider';
 import type {
   SSMGetOptions,
-  SSMGetOptionsUnion,
   SSMGetOutput,
 } from '../types/SSMProvider';
 
@@ -140,17 +139,17 @@ import type {
  * @param {SSMGetOptions} options - Options to configure the provider
  * @see https://awslabs.github.io/aws-lambda-powertools-typescript/latest/utilities/parameters/
  */
-const getParameter = <O extends SSMGetOptionsUnion | undefined = undefined>(
+const getParameter = <T = undefined, O extends SSMGetOptions | undefined = SSMGetOptions>(
   name: string,
   options?: O & SSMGetOptions
-): Promise<SSMGetOutput<O> | undefined> => {
+): Promise<SSMGetOutput<T, O> | undefined> => {
   if (!DEFAULT_PROVIDERS.hasOwnProperty('ssm')) {
     DEFAULT_PROVIDERS.ssm = new SSMProvider();
   }
 
   return (
     DEFAULT_PROVIDERS.ssm as SSMProvider
-  ).get(name, options) as Promise<SSMGetOutput<O> | undefined>;
+  ).get(name, options) as Promise<SSMGetOutput<T, O> | undefined>;
 };
 
 export {
diff --git a/packages/parameters/src/ssm/getParameters.ts b/packages/parameters/src/ssm/getParameters.ts
index ede4f3e614..1eb123dbbc 100644
--- a/packages/parameters/src/ssm/getParameters.ts
+++ b/packages/parameters/src/ssm/getParameters.ts
@@ -141,17 +141,17 @@ import type {
  * @param {SSMGetMultipleOptions} options - Options to configure the provider
  * @see https://awslabs.github.io/aws-lambda-powertools-typescript/latest/utilities/parameters/
  */
-const getParameters = <O extends SSMGetMultipleOptionsUnion | undefined = undefined>(
+const getParameters = <T = undefined, O extends SSMGetMultipleOptionsUnion | undefined = SSMGetMultipleOptionsUnion>(
   path: string,
   options?: O & SSMGetMultipleOptions
-): Promise<SSMGetMultipleOutput<O> | undefined> => {
+): Promise<SSMGetMultipleOutput<T, O> | undefined> => {
   if (!DEFAULT_PROVIDERS.hasOwnProperty('ssm')) {
     DEFAULT_PROVIDERS.ssm = new SSMProvider();
   }
 
   return (
     DEFAULT_PROVIDERS.ssm as SSMProvider
-  ).getMultiple(path, options) as Promise<SSMGetMultipleOutput<O> | undefined>;
+  ).getMultiple(path, options) as Promise<SSMGetMultipleOutput<T, O> | undefined>;
 };
 
 export {
diff --git a/packages/parameters/src/ssm/getParametersByName.ts b/packages/parameters/src/ssm/getParametersByName.ts
index 5efd333f5f..f7532206bd 100644
--- a/packages/parameters/src/ssm/getParametersByName.ts
+++ b/packages/parameters/src/ssm/getParametersByName.ts
@@ -1,6 +1,7 @@
 import { SSMProvider, DEFAULT_PROVIDERS } from './SSMProvider';
 import type {
-  SSMGetParametersByNameOptionsInterface
+  SSMGetParametersByNameOptionsInterface,
+  SSMGetParametersByNameOutput,
 } from '../types/SSMProvider';
 
 /**
@@ -160,15 +161,17 @@ import type {
  * @param {SSMGetParametersByNameOptionsInterface} options - Options to configure the provider
  * @see https://awslabs.github.io/aws-lambda-powertools-typescript/latest/utilities/parameters/
  */
-const getParametersByName = (
+const getParametersByName = <T = undefined>(
   parameters: Record<string, SSMGetParametersByNameOptionsInterface>,
   options?: SSMGetParametersByNameOptionsInterface
-): Promise<Record<string, unknown> & { _errors?: string[] }> => {
+): Promise<SSMGetParametersByNameOutput<T>> => {
   if (!DEFAULT_PROVIDERS.hasOwnProperty('ssm')) {
     DEFAULT_PROVIDERS.ssm = new SSMProvider();
   }
 
-  return (DEFAULT_PROVIDERS.ssm as SSMProvider).getParametersByName(parameters, options);
+  return (
+    DEFAULT_PROVIDERS.ssm as SSMProvider
+  ).getParametersByName(parameters, options) as Promise<SSMGetParametersByNameOutput<T>>;
 };
 
 export {
diff --git a/packages/parameters/src/types/BaseProvider.ts b/packages/parameters/src/types/BaseProvider.ts
index c0e5a08c3d..f2a6a79a9b 100644
--- a/packages/parameters/src/types/BaseProvider.ts
+++ b/packages/parameters/src/types/BaseProvider.ts
@@ -25,9 +25,9 @@ interface GetOptionsInterface {
    */
   sdkOptions?: unknown
   /**
-   * Transform to be applied, can be 'json', 'binary', or 'auto'.
+   * Transform to be applied, can be `json` or `binary`.
    */
-  transform?: TransformOptions
+  transform?: Omit<TransformOptions, 'auto'>
 }
 
 /**
@@ -40,6 +40,10 @@ interface GetOptionsInterface {
  * @property {boolean} throwOnTransformError - Whether to throw an error if a value cannot be transformed.
  */
 interface GetMultipleOptionsInterface extends GetOptionsInterface {
+  /**
+   * Transform to be applied, can be `json`, `binary`, or `auto`.
+   */
+  transform?: TransformOptions
   /**
    * Whether to throw an error if a value cannot be transformed.
    */
diff --git a/packages/parameters/src/types/SSMProvider.ts b/packages/parameters/src/types/SSMProvider.ts
index 292ed5a828..9a4c789978 100644
--- a/packages/parameters/src/types/SSMProvider.ts
+++ b/packages/parameters/src/types/SSMProvider.ts
@@ -63,6 +63,8 @@ interface SSMGetOptions extends GetOptionsInterface {
    * Additional options to pass to the AWS SDK v3 client. Supports all options from `GetParameterCommandInput`.
    */
   sdkOptions?: Partial<GetParameterCommandInput>
+
+  transform?: Exclude<TransformOptions, 'auto'>
 }
 
 interface SSMGetOptionsTransformJson extends SSMGetOptions {
@@ -77,14 +79,16 @@ interface SSMGetOptionsTransformNone extends SSMGetOptions {
   transform?: never
 }
 
-type SSMGetOptionsUnion = SSMGetOptionsTransformJson | SSMGetOptionsTransformBinary | SSMGetOptionsTransformNone | undefined;
-
-type SSMGetOutput<O = undefined> =
+/**
+ * Generic output type for the SSMProvider get method.
+ */
+type SSMGetOutput<T = undefined, O = undefined> =
+  undefined extends T ? 
     undefined extends O ? string :
       O extends SSMGetOptionsTransformNone | SSMGetOptionsTransformBinary ? string :
-        // eslint-disable-next-line @typescript-eslint/no-explicit-any
-        O extends SSMGetOptionsTransformJson ? Record<string, any> :
-          never;
+        O extends SSMGetOptionsTransformJson ? Record<string, unknown> :
+          never
+    : T;
 
 /**
  * Options for the SSMProvider getMultiple method.
@@ -126,18 +130,32 @@ interface SSMGetMultipleOptionsTransformBinary extends SSMGetMultipleOptions {
   transform: 'binary'
 }
 
+interface SSMGetMultipleOptionsTransformAuto extends SSMGetMultipleOptions {
+  transform: 'auto'
+}
+
 interface SSMGetMultipleOptionsTransformNone extends SSMGetMultipleOptions {
   transform?: never
 }
 
-type SSMGetMultipleOptionsUnion = SSMGetMultipleOptionsTransformJson | SSMGetMultipleOptionsTransformBinary | SSMGetMultipleOptionsTransformNone | undefined;
+type SSMGetMultipleOptionsUnion = 
+  SSMGetMultipleOptionsTransformJson |
+  SSMGetMultipleOptionsTransformBinary |
+  SSMGetMultipleOptionsTransformAuto |
+  SSMGetMultipleOptionsTransformNone |
+  undefined;
 
-type SSMGetMultipleOutput<O = undefined> =
+/**
+ * Generic output type for the SSMProvider getMultiple method.
+ */
+type SSMGetMultipleOutput<T = undefined, O = undefined> =
+  undefined extends T ? 
     undefined extends O ? Record<string, string> :
       O extends SSMGetMultipleOptionsTransformNone | SSMGetMultipleOptionsTransformBinary ? Record<string, string> :
-        // eslint-disable-next-line @typescript-eslint/no-explicit-any
-        O extends SSMGetMultipleOptionsTransformJson ? Record<string, Record<string, any>> :
-          never;
+        O extends SSMGetMultipleOptionsTransformAuto ? Record<string, unknown> :
+          O extends SSMGetMultipleOptionsTransformJson ? Record<string, Record<string, unknown>> :
+            never
+    : Record<string, T>;
 
 /**
  * Options for the SSMProvider getParametersByName method.
@@ -152,7 +170,7 @@ interface SSMGetParametersByNameOptionsInterface {
   maxAge?: number
   throwOnError?: boolean
   decrypt?: boolean
-  transform?: TransformOptions
+  transform?: Exclude<TransformOptions, 'auto'>
 }
 
 /**
@@ -179,10 +197,14 @@ type SSMGetParametersByNameFromCacheOutputType = {
   toFetch: Record<string, SSMGetParametersByNameOptionsInterface>
 };
 
+type SSMGetParametersByNameOutput<T = undefined> = 
+  undefined extends T ?
+    Record<string, unknown> & { _errors?: string[] } :
+    Record<string, T> & { _errors?: string[] };
+
 export type {
   SSMProviderOptions,
   SSMGetOptions,
-  SSMGetOptionsUnion,
   SSMGetOutput,
   SSMGetMultipleOptions,
   SSMGetMultipleOptionsUnion,
@@ -191,4 +213,5 @@ export type {
   SSMSplitBatchAndDecryptParametersOutputType,
   SSMGetParametersByNameOutputInterface,
   SSMGetParametersByNameFromCacheOutputType,
+  SSMGetParametersByNameOutput,
 };
\ No newline at end of file

From e87c89ff061fa93e8dc6fa8c1da942ad68a9e549 Mon Sep 17 00:00:00 2001
From: Andrea Amorosi <dreamorosi@gmail.com>
Date: Wed, 29 Mar 2023 23:16:34 +0200
Subject: [PATCH 4/5] chore: rebase

---
 packages/parameters/src/ssm/SSMProvider.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/parameters/src/ssm/SSMProvider.ts b/packages/parameters/src/ssm/SSMProvider.ts
index 6d59f93fed..ba1794e98f 100644
--- a/packages/parameters/src/ssm/SSMProvider.ts
+++ b/packages/parameters/src/ssm/SSMProvider.ts
@@ -737,7 +737,7 @@ class SSMProvider extends BaseProvider {
   }
 
   protected resolveDecryptionConfigValue(
-    options: SSMGetOptionsInterface | SSMGetMultipleOptionsInterface = {},
+    options: SSMGetOptions | SSMGetMultipleOptions = {},
     sdkOptions?: GetParameterCommandInput | GetParametersByPathCommandInput
   ): boolean | undefined {
     if (options?.decrypt !== undefined) return options.decrypt;

From 1b0cd0bac9a49e6d81b0574b2f81fbe9f9e65fc4 Mon Sep 17 00:00:00 2001
From: Andrea Amorosi <dreamorosi@gmail.com>
Date: Wed, 5 Apr 2023 13:40:23 +0000
Subject: [PATCH 5/5] chore: added type annotation to tests to use as canary

---
 .../tests/unit/getParameter.test.ts           | 58 +++++++++++++++-
 .../tests/unit/getParameters.test.ts          | 66 ++++++++++++++++++-
 2 files changed, 118 insertions(+), 6 deletions(-)

diff --git a/packages/parameters/tests/unit/getParameter.test.ts b/packages/parameters/tests/unit/getParameter.test.ts
index f13f993cbf..b7bf839f57 100644
--- a/packages/parameters/tests/unit/getParameter.test.ts
+++ b/packages/parameters/tests/unit/getParameter.test.ts
@@ -9,6 +9,10 @@ import { SSMClient, GetParameterCommand } from '@aws-sdk/client-ssm';
 import { mockClient } from 'aws-sdk-client-mock';
 import 'aws-sdk-client-mock-jest';
 
+/**
+ * Note that the following tests include type annotations on the results of each call. This is to ensure that the
+ * generic types defined in the utility are working as expected. If they are not, the tests will fail to compile.
+ */
 describe('Function: getParameter', () => {
 
   beforeEach(() => {
@@ -27,7 +31,7 @@ describe('Function: getParameter', () => {
     });
 
     // Act
-    const value = await getParameter(parameterName);
+    const value: string | undefined = await getParameter(parameterName);
 
     // Assess
     expect(client).toReceiveCommandWith(GetParameterCommand, {
@@ -36,7 +40,7 @@ describe('Function: getParameter', () => {
     expect(value).toBe(parameterValue);
 
   });
-  
+
   test('when called and a default provider exists, it uses it and returns the value', async () => {
 
     // Prepare
@@ -51,7 +55,7 @@ describe('Function: getParameter', () => {
     });
 
     // Act
-    const value = await getParameter(parameterName);
+    const value: string | undefined = await getParameter(parameterName);
 
     // Assess
     expect(client).toReceiveCommandWith(GetParameterCommand, {
@@ -62,4 +66,52 @@ describe('Function: getParameter', () => {
 
   });
 
+  test('when called and transform `JSON` is specified, it returns an object with correct type', async () => {
+
+    // Prepare
+    const provider = new SSMProvider();
+    DEFAULT_PROVIDERS.ssm = provider;
+    const parameterName = 'foo';
+    const parameterValue = JSON.stringify({ hello: 'world' });
+    const client = mockClient(SSMClient).on(GetParameterCommand).resolves({
+      Parameter: {
+        Value: parameterValue,
+      },
+    });
+
+    // Act
+    const value: Record<string, unknown> | undefined = await getParameter(parameterName, { transform: 'json' });
+
+    // Assess
+    expect(client).toReceiveCommandWith(GetParameterCommand, {
+      Name: parameterName,
+    });
+    expect(value).toStrictEqual(JSON.parse(parameterValue));
+
+  });
+
+  test('when called and transform `JSON` is specified as well as an explicit `K` type, it returns a result with correct type', async () => {
+
+    // Prepare
+    const provider = new SSMProvider();
+    DEFAULT_PROVIDERS.ssm = provider;
+    const parameterName = 'foo';
+    const parameterValue = JSON.stringify(5);
+    const client = mockClient(SSMClient).on(GetParameterCommand).resolves({
+      Parameter: {
+        Value: parameterValue,
+      },
+    });
+
+    // Act
+    const value: number | undefined = await getParameter<number>(parameterName, { transform: 'json' });
+
+    // Assess
+    expect(client).toReceiveCommandWith(GetParameterCommand, {
+      Name: parameterName,
+    });
+    expect(value).toBe(JSON.parse(parameterValue));
+
+  });
+
 });
\ No newline at end of file
diff --git a/packages/parameters/tests/unit/getParameters.test.ts b/packages/parameters/tests/unit/getParameters.test.ts
index 8f9b68f6bd..2025c0ae7f 100644
--- a/packages/parameters/tests/unit/getParameters.test.ts
+++ b/packages/parameters/tests/unit/getParameters.test.ts
@@ -9,6 +9,10 @@ import { SSMClient, GetParametersByPathCommand } from '@aws-sdk/client-ssm';
 import { mockClient } from 'aws-sdk-client-mock';
 import 'aws-sdk-client-mock-jest';
 
+/**
+ * Note that the following tests include type annotations on the results of each call. This is to ensure that the
+ * generic types defined in the utility are working as expected. If they are not, the tests will fail to compile.
+ */
 describe('Function: getParameters', () => {
 
   beforeEach(() => {
@@ -28,7 +32,7 @@ describe('Function: getParameters', () => {
     });
 
     // Act
-    const parameters = await getParameters(parameterPath);
+    const parameters: Record<string, string> | undefined = await getParameters(parameterPath);
 
     // Assess
     expect(client).toReceiveCommandWith(GetParametersByPathCommand, {
@@ -39,7 +43,7 @@ describe('Function: getParameters', () => {
     });
 
   });
-  
+
   test('when called and a default provider exists, it uses it and returns the value', async () => {
 
     // Prepare
@@ -55,7 +59,7 @@ describe('Function: getParameters', () => {
     });
 
     // Act
-    const parameters = await getParameters(parameterPath);
+    const parameters: Record<string, string> | undefined = await getParameters(parameterPath);
 
     // Assess
     expect(client).toReceiveCommandWith(GetParametersByPathCommand, {
@@ -68,4 +72,60 @@ describe('Function: getParameters', () => {
 
   });
 
+  test('when called and transform `JSON` is specified, it returns an object with correct type', async () => {
+
+    // Prepare
+    const provider = new SSMProvider();
+    DEFAULT_PROVIDERS.ssm = provider;
+    const parameterPath = '/foo';
+    const parameterValue = JSON.stringify({ hello: 'world' });
+    const client = mockClient(SSMClient).on(GetParametersByPathCommand).resolves({
+      Parameters: [{
+        Name: '/foo/bar',
+        Value: parameterValue,
+      }],
+    });
+
+    // Act
+    const parameters: Record<string, Record<string, unknown>> | undefined = await getParameters(parameterPath);
+
+    // Assess
+    expect(client).toReceiveCommandWith(GetParametersByPathCommand, {
+      Path: parameterPath,
+    });
+    expect(parameters).toStrictEqual({
+      'bar': parameterValue,
+    });
+    expect(DEFAULT_PROVIDERS.ssm).toBe(provider);
+
+  });
+
+  test('when called and transform `JSON` is specified as well as an explicit `K` type, it returns a result with correct type', async () => {
+
+    // Prepare
+    const provider = new SSMProvider();
+    DEFAULT_PROVIDERS.ssm = provider;
+    const parameterPath = '/foo';
+    const parameterValue = JSON.stringify(5);
+    const client = mockClient(SSMClient).on(GetParametersByPathCommand).resolves({
+      Parameters: [{
+        Name: '/foo/bar',
+        Value: parameterValue,
+      }],
+    });
+
+    // Act
+    const parameters: Record<string, Record<string, number>> | undefined = await getParameters<Record<string, number>>(parameterPath);
+
+    // Assess
+    expect(client).toReceiveCommandWith(GetParametersByPathCommand, {
+      Path: parameterPath,
+    });
+    expect(parameters).toStrictEqual({
+      'bar': parameterValue,
+    });
+    expect(DEFAULT_PROVIDERS.ssm).toBe(provider);
+
+  });
+
 });
\ No newline at end of file