---
URL: "/guide/core/patch"
LLMS_URL: "/guide/core/patch/llms.txt"
---
# Create `PATCH` *endpoint*

<!--@include: ../../partials/coming-soon.md-->

## Usage

```js twoslash
import { App } from 'backan'

const id    = 'patch'
const route = new App(  )

const {
 validation: v,
 response,
} = route

route.add(
 {
  method  : 'patch',
  path    : '/:id',
  summary : 'Update partial resource by ID',
  request : {
   params : v.object( { id: v.string() } ),
   body   : { content : { 'application/json' : { schema : v.object( {
    name  : v.string().optional(),
    value : v.number().optional(),
   } ) } } },
  },
  responses : {
   200 : response.responseJSONSuccess(
    v.object( {
     updated       : v.boolean(),
     id            : v.string(),
     updatedFields : v.array( v.string() ), // List of updated fields
    } ),
   ),
   400 : response.responseJSONError400,
   404 : response.responseJSONError404,
   500 : response.responseJSONError500,
  },
  tags : [ id ],
 },
 async c => {

  try {

   const { id }  = c.req.valid( 'param' )
   const updates = c.req.valid( 'json' )

   console.log( `Updating resource ${id} with updates:`, updates )

   const updatedFields = Object.keys( updates )

   // Simulate partial update success
   return response.addSuccessResponse( c, {
    updated : true,
    id,
    updatedFields,
   } )

  }
  catch ( e ) {

   // Uncomment if needed
   // if (e instanceof SomeValidationError) {
   //   return response.add400Error(c, e);
   // }

   return response.add500Error( c, e )

  }

 },
)

export default route

```