Endpoint Performs a partial update on an existing task. Only the fields you include in the request body will be updated. The API automatically manages the updatedAt timestamp and finishedAt timestamp based on changes to the completed field.
Path Parameters The unique identifier (UUID) of the task to update. Example: 550e8400-e29b-41d4-a716-446655440000
Request Body All fields are optional - include only the fields you want to update.
Updated task title. Validation:
Minimum length: 3 characters
Maximum length: 25 characters
Automatically trimmed
Example: "Updated task title" Updated task description. Validation:
Maximum length: 25 characters
Automatically trimmed
Example: "Updated description" Updated completion status. Automatic Behavior:
When changed from false to true: finishedAt is automatically set to current timestamp
When changed from true to false: finishedAt is automatically removed
Example: true Updated category assignment. Special Values:
Empty string ("") assigns task to "uncategorized"
Valid UUID assigns task to that category
Example: "550e8400-e29b-41d4-a716-446655440000" or "" Do not include _id, createdAt, updatedAt, or finishedAt in your request. These fields are managed automatically by the API. Any attempt to set them will be ignored.
Response Returns the complete updated task object with all fields.
The task’s unique identifier (unchanged).
The task title (updated if provided in request).
The task description (updated if provided in request).
The completion status (updated if provided in request).
The category ID (updated if provided in request).
The original creation timestamp (unchanged).
Automatically set to current timestamp.
Automatically managed based on completed status changes.
Status Codes
200 OK - Task successfully updated400 Bad Request - Validation failed on provided fields404 Not Found - No task exists with the provided ID
Examples cURL - Mark as Completed
cURL - Update Title and Description
cURL - Change Category
cURL - Remove Category (Set to Uncategorized)
JavaScript - Mark as Completed
JavaScript - Update Multiple Fields
JavaScript - With Error Handling
curl -X PATCH http://localhost:3000/api/tasks/550e8400-e29b-41d4-a716-446655440000 \ -H "Content-Type: application/json" \ -d '{"completed":true}'
Request Examples Mark as Completed
Mark as Incomplete
Update Title Only
Update Multiple Fields
Remove Category
Response Examples 200 OK - Task Marked as Completed
200 OK - Task Marked as Incomplete
200 OK - Category Changed
404 Not Found
400 Bad Request
{ "_id" : "550e8400-e29b-41d4-a716-446655440000" , "title" : "Write API documentation" , "description" : "Create comprehensive docs" , "completed" : true , "categoryId" : "a1b2c3d4-e5f6-4a5b-8c9d-0e1f2a3b4c5d" , "createdAt" : "2026-03-11T10:00:00.000Z" , "updatedAt" : "2026-03-11T16:00:00.000Z" , "finishedAt" : "2026-03-11T16:00:00.000Z" }
Automatic Field Management updatedAt Timestamp The updatedAt field is always set to the current timestamp on every update, regardless of which fields you modify.
finishedAt Timestamp Logic Mark as Complete
Mark as Incomplete
No Change
When completed changes from false to true: Before: { "completed" : false // finishedAt not present }
Request: After: { "completed" : true , "finishedAt" : "2026-03-11T16:00:00.000Z" }
When completed changes from true to false: Before: { "completed" : true , "finishedAt" : "2026-03-11T16:00:00.000Z" }
Request: After: { "completed" : false // finishedAt removed }
When completed is not modified or remains the same: Request: Result:
finishedAt remains unchangedOnly title and updatedAt are modified
Common Use Cases Toggle Task Completion async function toggleTaskCompletion ( taskId ) { // First, get the current task const getResponse = await fetch ( `http://localhost:3000/api/tasks/ ${ taskId } ` ); const task = await getResponse . json (); // Toggle the completion status const updateResponse = await fetch ( `http://localhost:3000/api/tasks/ ${ taskId } ` , { method: 'PATCH' , headers: { 'Content-Type' : 'application/json' }, body: JSON . stringify ({ completed: ! task . completed }) }); return await updateResponse . json (); }
Move Task to Different Category async function moveTaskToCategory ( taskId , newCategoryId ) { const response = await fetch ( `http://localhost:3000/api/tasks/ ${ taskId } ` , { method: 'PATCH' , headers: { 'Content-Type' : 'application/json' }, body: JSON . stringify ({ categoryId: newCategoryId }) }); if ( response . ok ) { const updatedTask = await response . json (); console . log ( `Task moved to category: ${ updatedTask . categoryId } ` ); return updatedTask ; } }
Rename Task async function renameTask ( taskId , newTitle ) { const response = await fetch ( `http://localhost:3000/api/tasks/ ${ taskId } ` , { method: 'PATCH' , headers: { 'Content-Type' : 'application/json' }, body: JSON . stringify ({ title: newTitle }) }); return await response . json (); }
Update Task Description async function updateDescription ( taskId , newDescription ) { const response = await fetch ( `http://localhost:3000/api/tasks/ ${ taskId } ` , { method: 'PATCH' , headers: { 'Content-Type' : 'application/json' }, body: JSON . stringify ({ description: newDescription }) }); return await response . json (); }
Usage Notes Partial Updates : This is a PATCH endpoint, which means you only need to include fields you want to change. Unspecified fields remain unchanged.
Optimistic UI Updates : You can update your UI immediately when the user makes changes, then sync with the API in the background for better perceived performance.
Category Validation : The API does not validate whether the categoryId you provide exists. Make sure you’re using valid category UUIDs.
Empty String Behavior : Setting categoryId to an empty string ("") will assign the task to "uncategorized". This is equivalent to removing the category assignment.
