Response

Mali Response class encasulates the response of a call. Clients to not create this. Mali does it for us. It is accessible via the context response property. Some ctx properties and methods are just delegated to the response object. It allows us to sent the response payload, alongside any header and trailer metadata.

Example

async function sayHello(ctx) {
  // set some value to the response header metadata
  ctx.response.set('foo', 'bar')) // 'bar'

  console.log(ctx.response.type) // 'unary'

  // set some value to the response trailer / status metatada
  ctx.response.setStatus('biz', 'baz')

  // set the actual payload
  ctx.response.res = { message: `Hello ${ctx.req.name}!` }
}

Properties

response.call

The internal gRPC call instance reference.

response.type

The call type. One of CallType enums.

console.log(ctx.response.type) // 'unary'

response.metadata

The call's response header metadata plain object.

ctx.response.set('foo', 'bar')
console.log(ctx.response.metadata)  // { 'foo': 'bar' }

response.status

The call's response status / trailer metadata plain object.

ctx.response.setStatus('biz', 'baz')
console.log(ctx.response.status)  // { biz: 'baz' }

response.res

The actual call response payload object. This is set only in case of DUPLEX calls, to the the gRPC call reference itself. In all other cases set the res property to the actual response message / object in case of UNIRY and REQUEST_STREAM calls, and to the output stream in case of RESPONSE_STREAM calls. When a stream it is automatically piped into the call.

ctx.response.res = { foo: 'bar' }

For stream response calls:

ctx.response.res = createResponseStream()

Since in DUPLEX calls res is just the call instance itself, we can use it to write back to the client:

ctx.response.res.write({ foo: 'bar' })

Functions

response.get()

Get a response header metadata value.

console.log(ctx.response.get('foo')) // 'bar'

response.set()

Set a response header metadata value.

ctx.response.set('foo', 'bar')

Or using an object:

ctx.response.set({
  foo: 'bar'
})

response.getMetadata()

Get response header metadata as a grpc.Metadata object.

response.sendMetadata()

Send response header metadata. Optionally provide header metadata object directly as an argument and that is set and sent. If param is not provided sendMetadata sends the existing metadata in the response. If it is provided existin metadata is cleared and is set to the object adn then sent.

ctx.response.sendMetadata({
  foo: 'bar'
})

reponse.setStatus()

Set a reponse status / trailer metadata value.

ctx.response.setStatus('foo', 'bar')

Or using an object

ctx.response.setStatus({
  foo: 'bar'
})

reponse.getStatus()

Get a reponse status / trailer metadata value.

console.log(ctx.response.getStatus('foo')) // 'bar'

reponse.getStatusMetadata()

Get reponse status / trailer metadata as a grpc.Metadata object.