Grouping APIs by tags in Spring Boot - Step-by-Step Execution

Concept Flow - Grouping APIs by tags

Define API Controller

↓

Add Tag Annotation

↓

Define API Endpoints

↓

Run Application

↓

API Docs Show Grouped Tags

↓

User Sees APIs Grouped by Tags

This flow shows how adding tags to API controllers groups endpoints in documentation tools like Swagger.

Execution Sample

Spring Boot

@Tag(name = "User")
@RestController
@RequestMapping("/users")
public class UserController {
  @GetMapping
  public List<User> getAll() { return List.of(); }
}

This code defines a User API controller tagged as 'User' to group its endpoints.

Execution Table

Step	Action	Annotation Processed	Effect on API Docs	Output
1	Start application	No tags processed yet	No grouping in docs	API docs show all endpoints ungrouped
2	Read @Tag(name = "User") on UserController	Tag 'User' assigned	Endpoints under UserController grouped under 'User'	User endpoints grouped in docs
3	Read @GetMapping on getAll()	Endpoint registered	Endpoint appears under 'User' tag	GET /users listed under 'User'
4	Application running	Tags and endpoints loaded	Grouping visible in Swagger UI	User tag with GET /users endpoint shown
5	User views docs	Tags used for grouping	Easier navigation by tag	User sees APIs grouped by tags

💡 Application fully started with API endpoints grouped by tags for documentation.

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
tags	[]	["User"]	["User"]	["User"]	["User"]
endpoints	[]	[]	["GET /users"]	["GET /users"]	["GET /users"]
apiDocsGrouping	None	Partial	Partial	Complete	Complete

Key Moments - 2 Insights

Why do APIs appear grouped under tags in documentation?

Because the @Tag annotation assigns a name to the controller or endpoint, which documentation tools use to group APIs. See execution_table step 2 and 4.

What happens if no @Tag annotation is added?

APIs appear ungrouped or under a default group in docs, making navigation harder. This is shown in execution_table step 1.

Visual Quiz - 3 Questions

Look at the execution_table at step 3, what endpoint is registered under the 'User' tag?

A DELETE /users

B POST /users

C GET /users

D PUT /users

💡 Hint

Check the 'Output' column at step 3 in execution_table.

At which step does the API documentation show grouping by tags?

A Step 4

B Step 1

C Step 2

D Step 5

💡 Hint

Look at the 'Effect on API Docs' column for when grouping is complete.

If you remove the @Tag annotation, how does the variable 'tags' change after step 2?

A It contains 'User'

B It becomes empty []

C It contains multiple tags

D It causes an error

💡 Hint

Refer to variable_tracker 'tags' value after step 2.

Concept Snapshot

Use @Tag(name = "TagName") on controllers or methods.
This groups APIs in documentation tools like Swagger.
Without tags, APIs appear ungrouped.
Tags improve API navigation and clarity.
Run app to see grouping in Swagger UI.

Full Transcript

Grouping APIs by tags in Spring Boot means adding the @Tag annotation to your API controllers or methods. This annotation assigns a name that documentation tools like Swagger use to group your endpoints. When the application starts, it reads these tags and organizes the API docs accordingly. Without tags, all APIs appear in one list, which can be confusing. Adding tags helps users find related APIs easily. For example, a UserController with @Tag(name = "User") will have all its endpoints grouped under 'User' in the docs. This process happens during app startup and is visible in the Swagger UI.