3. Mutations

Last updated: 2 minutes read.

Now that we have attached datasources to our Query in the schema let’s try to do the same for Mutation.

1. Update Schema

type Mutation {
  addReview(text: String, userId: String): Review
  deletReview(reviewId: String): String

We’ll update the Mutatation type as above where we’ll add two operations

  • addReview: Which accepts two arguments (i.e text and userId) and adds a new review by making a POST request to http://localhost:4001/reviews endpoint, which expects something like the following in the request payload
    "id": "1", // UserId of the user posting review 
    "text": "New Review by John Doe11" // review text
  • deleteReview: Which accepts one argument (i.e reviewId), that deletes a review by making a DELETE request to http://localhost:4001/reviews/:reviewId

2. Configure datasource.

Follow these steps to configure a data source for the Mutation.

  • Navigate to schema tab in the api where you would see the split screen view of schema editor on left and list of configurable fields on right
  • Select addReview field from Mutation type
  • Select REST option
  • Set a unique datasource name
  • Set the URL as http://localhost:4001/reviews
  • Select method type as POST
  • Set request body to relay the graphql arguments to our upstream payload as follows:
  "text": "{{.arguments.text}}",
  "userId": "{{.arguments.userId}}"
  • Update the API

3. Execute mutation operation

We can now test our mutation operation with the playground in API designer using the following operation

mutation AddReview {
  addReview(text: "review using udg", userId:"1"){

That should return us the following response:

  "data": {
    "addReview": {
      "id": "e201e6f3-b582-4772-b95a-d25199b4ab82",
      "text": "review using udg"


Configure a datasource to delete a review using review id.


- For users field on type Review
- - Description :: delete review using reviewId
- - URL :: http://localhost:4001/reviews/:reviewId
- - Method :: DELETE

- Enable field mapping to map your API response 


You can find the solution for the challenge in the above video.

Now that we have a good idea how we could do CRUD operations with UDG APIs, let’s see how we can secure them using policies