feat: add cast array to expected array query params

README.md

@@ -378,6 +378,28 @@ getUsers(@QueryParam("limit") limit: number) {
 }
 ```
 
+You can use `isArray` option to get a query param array. This will cast the query param :
+
+```typescript
+@Get("/users/by-multiple-ids")
+getUsers(@QueryParam("ids", { isArray: true}) ids: string[]) {
+}
+```
+
+`GET /users/by-multiple-ids?ids=a` → `ids = ['a']`
+`GET /users/by-multiple-ids?ids=a&ids=b` → `ids = ['a', 'b']`
+
+You can combine use `isArray` option with `type` option to get a query param array of one type. This will cast the query param :
+
+```typescript
+@Get("/users/by-multiple-ids")
+getUsers(@QueryParam("ids", { isArray: true, type: Number}) ids: number[]) {
+}
+```
+
+`GET /users/by-multiple-ids?ids=1` → `ids = [1]`
+`GET /users/by-multiple-ids?ids=1&ids=3.5` → `ids = [1, 3.5]`
+
 If you want to inject all query parameters use `@QueryParams()` decorator.
 The bigest benefit of this approach is that you can perform validation of the params.
 
@@ -402,12 +424,17 @@ class GetUsersQuery {
     @IsBoolean()
     isActive: boolean;
 
+    @IsArray()
+    @IsNumber(undefined, { each: true })
+    @Type(() => Number)
+    ids: number[];
 }
 
 @Get("/users")
 getUsers(@QueryParams() query: GetUsersQuery) {
     // here you can access query.role, query.limit
     // and others valid query parameters
+    // query.ids will be an array, of numbers, even with one element
 }
 ```
 
@@ -1535,7 +1562,7 @@ export class QuestionController {
 
 | Signature                                                        | Example                                           | Description                                                                                                                                 |
 | ---------------------------------------------------------------- | ------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------- |
-| `@Authorized(roles?: string\|string[])`                          | `@Authorized("SUPER_ADMIN")` get()                | Checks if user is authorized and has given roles on a given route. `authorizationChecker` should be defined in routing-controllers options. |  |
+| `@Authorized(roles?: string\|string[])`                          | `@Authorized("SUPER_ADMIN")` get()                | Checks if user is authorized and has given roles on a given route. `authorizationChecker` should be defined in routing-controllers options. |
 | `@CurrentUser(options?: { required?: boolean })`                 | get(@CurrentUser({ required: true }) user: User)  | Injects currently authorized user. `currentUserChecker` should be defined in routing-controllers options.                                   |
 | `@Header(headerName: string, headerValue: string)`               | `@Header("Cache-Control", "private")` get()       | Allows to explicitly set any HTTP header returned in the response.                                                                          |
 | `@ContentType(contentType: string)`                              | `@ContentType("text/csv")` get()                  | Allows to explicitly set HTTP Content-Type returned in the response.                                                                        |

src/ActionParameterHandler.ts

@@ -130,8 +130,13 @@ export class ActionParameterHandler<T extends BaseDriver> {
         case 'string':
         case 'boolean':
         case 'date':
-          return this.normalizeStringValue(value, param.name, param.targetName);
+          const normalizedValue = this.normalizeStringValue(value, param.name, param.targetName);
+          return param.isArray ? [normalizedValue] : normalizedValue;
+        case 'array':
+          return [value];
       }
+    } else if (Array.isArray(value)) {
+      return value.map(v => this.normalizeStringValue(v, param.name, param.targetName));
     }
 
     // if target type is not primitive, transform and validate it
@@ -188,10 +193,14 @@ export class ActionParameterHandler<T extends BaseDriver> {
    */
   protected parseValue(value: any, paramMetadata: ParamMetadata): any {
     if (typeof value === 'string') {
-      try {
-        return JSON.parse(value);
-      } catch (error) {
-        throw new ParameterParseJsonError(paramMetadata.name, value);
+      if (['queries', 'query'].includes(paramMetadata.type) && paramMetadata.targetName === 'array') {
+        return [value];
+      } else {
+        try {
+          return JSON.parse(value);
+        } catch (error) {
+          throw new ParameterParseJsonError(paramMetadata.name, value);
+        }
       }
     }
     return value;

src/decorator-options/ParamOptions.ts

@@ -32,4 +32,9 @@ export interface ParamOptions {
    * Explicitly set type which should be used for param to perform transformation.
    */
   type?: any;
+
+  /**
+   * Force value to be cast as an array.
+   */
+  isArray?: boolean;
 }

src/decorator/QueryParam.ts

@@ -18,6 +18,7 @@ export function QueryParam(name: string, options?: ParamOptions): Function {
       classTransform: options ? options.transform : undefined,
       explicitType: options ? options.type : undefined,
       validate: options ? options.validate : undefined,
+      isArray: options?.isArray ?? false,
     });
   };
 }

src/metadata/ParamMetadata.ts

@@ -78,6 +78,11 @@ export class ParamMetadata {
    */
   transform: (action: Action, value?: any) => Promise<any> | any;
 
+  /**
+   * If true, string values are cast to arrays
+   */
+  isArray?: boolean;
+
   /**
    * Additional parameter options.
    * For example it can be uploader middleware options or body-parser middleware options.
@@ -113,6 +118,7 @@ export class ParamMetadata {
     this.transform = args.transform;
     this.classTransform = args.classTransform;
     this.validate = args.validate;
+    this.isArray = args.isArray;
 
     if (args.explicitType) {
       this.targetType = args.explicitType;

src/metadata/args/ParamMetadataArgs.ts

@@ -66,4 +66,9 @@ export interface ParamMetadataArgs {
    * Explicitly set type which should be used for Body to perform transformation.
    */
   explicitType?: any;
+
+  /**
+   * Explicitly tell that the QueryParam is an array to force routing-controller to cast it
+   */
+  isArray?: boolean;
 }