What is the difference between @Param('id') and @Param() with no argument in NestJS?

Q: What is the difference between @Param('id') and @Param() with no argument in NestJS?

// Single param — injects the string '42' @Get(':id') findOne(@Param('id') id: string) { // id === '42' for GET /users/42 } // All params — injects { userId: '1', postId: '7' } @Get(':userId/posts/:postId') findPost(@Param() params: Record ) { const { userId, postId } = params; } // Typed interface — better than Record for known shapes interface PostParams { userId: string; postId: string; } findPost(@Param() params: PostParams) {} // Always use pipes for type conversion @Get(':id') findOne(@Param('id', ParseIntPipe) id: number) { // id is now a number, not a string } @Param('key') — extracts a single named param; injects a string. @Param() with no arg — injects the full params object with all route params as strings. Route params are ALWAYS strings before pipe transformation — never assume a numeric type. Use ParseIntPipe, ParseUUIDPipe, or a custom pipe to convert the string to the right type. Use a typed interface with @Param() for multiple known params instead of Record .

Difficulty: 4/10

parameter decorators, routing, validation

@Param('id') extracts a single named route parameter by key and injects it as a string. @Param() with no argument injects the entire params object containing all route parameters as a plain object. Route params are always strings before pipe transformation regardless of which form is used.

Single param vs full params object

Key rules for @Param():

1
@Param('key') — extracts a single named param; injects a string.
2
@Param() with no arg — injects the full params object with all route params as strings.
3
Route params are ALWAYS strings before pipe transformation — never assume a numeric type.
4
Use ParseIntPipe, ParseUUIDPipe, or a custom pipe to convert the string to the right type.
5
Use a typed interface with @Param() for multiple known params instead of Record<string, string>.

Scenario Questions

0-2 years experience

Follow-up Questions