Support followers for Database (#21169)

openmetadata-service/src/main/java/org/openmetadata/service/resources/databases/DatabaseResource.java

@@ -79,7 +79,7 @@ public class DatabaseResource extends EntityResource<Database, DatabaseRepositor
   public static final String COLLECTION_PATH = "v1/databases/";
   private final DatabaseMapper mapper = new DatabaseMapper();
   static final String FIELDS =
-      "owners,databaseSchemas,usageSummary,location,tags,extension,domain,sourceHash";
+      "owners,databaseSchemas,usageSummary,location,tags,extension,domain,sourceHash,followers";
 
   @Override
   public Database addHref(UriInfo uriInfo, Database db) {
@@ -757,4 +757,65 @@ public class DatabaseResource extends EntityResource<Database, DatabaseRepositor
     Database database = repository.deleteDatabaseProfilerConfig(id);
     return addHref(uriInfo, database);
   }
+
+  @PUT
+  @Path("/{id}/followers")
+  @Operation(
+      operationId = "addFollowerToDatabase",
+      summary = "Add a follower",
+      description = "Add a user identified by `userId` as followed of this Database",
+      responses = {
+        @ApiResponse(
+            responseCode = "200",
+            description = "OK",
+            content =
+                @Content(
+                    mediaType = "application/json",
+                    schema = @Schema(implementation = ChangeEvent.class))),
+        @ApiResponse(responseCode = "404", description = "Database for instance {id} is not found")
+      })
+  public Response addFollower(
+      @Context UriInfo uriInfo,
+      @Context SecurityContext securityContext,
+      @Parameter(description = "Id of the Database", schema = @Schema(type = "UUID"))
+          @PathParam("id")
+          UUID id,
+      @Parameter(
+              description = "Id of the user to be added as follower",
+              schema = @Schema(type = "string"))
+          UUID userId) {
+    return repository
+        .addFollower(securityContext.getUserPrincipal().getName(), id, userId)
+        .toResponse();
+  }
+
+  @DELETE
+  @Path("/{id}/followers/{userId}")
+  @Operation(
+      operationId = "deleteFollower",
+      summary = "Remove a follower",
+      description = "Remove the user identified `userId` as a follower of the entity.",
+      responses = {
+        @ApiResponse(
+            responseCode = "200",
+            description = "OK",
+            content =
+                @Content(
+                    mediaType = "application/json",
+                    schema = @Schema(implementation = ChangeEvent.class)))
+      })
+  public Response deleteFollower(
+      @Context UriInfo uriInfo,
+      @Context SecurityContext securityContext,
+      @Parameter(description = "Id of the Entity", schema = @Schema(type = "UUID")) @PathParam("id")
+          UUID id,
+      @Parameter(
+              description = "Id of the user being removed as follower",
+              schema = @Schema(type = "string"))
+          @PathParam("userId")
+          String userId) {
+    return repository
+        .deleteFollower(securityContext.getUserPrincipal().getName(), id, UUID.fromString(userId))
+        .toResponse();
+  }
 }

openmetadata-service/src/test/java/org/openmetadata/service/resources/databases/DatabaseResourceTest.java

@@ -333,7 +333,7 @@ public class DatabaseResourceTest extends EntityResourceTest<Database, CreateDat
         database.getUsageSummary(),
         database.getLocation());
 
-    fields = "owners,databaseSchemas,usageSummary,location,tags";
+    fields = "owners,databaseSchemas,usageSummary,location,tags,followers";
     database =
         byName
             ? getEntityByName(database.getFullyQualifiedName(), fields, ADMIN_AUTH_HEADERS)

openmetadata-spec/src/main/resources/json/schema/entity/data/database.json

@@ -128,6 +128,10 @@
     "certification": {
       "$ref": "../../type/assetCertification.json"
     },
+    "followers": {
+      "description": "Followers of this entity.",
+      "$ref": "../../type/entityReferenceList.json"
+    },
     "sourceHash": {
       "description": "Source hash of the entity",
       "type": "string",

openmetadata-ui/src/main/resources/ui/src/generated/entity/data/database.ts

@@ -59,6 +59,10 @@ export interface Database {
      * Entity extension data with custom attributes added to the entity.
      */
     extension?: any;
+    /**
+     * Followers of this entity.
+     */
+    followers?: EntityReference[];
     /**
      * Name that uniquely identifies a database in the format 'ServiceName.DatabaseName'.
      */