AppSync - creating nested mutation with array and objects?

Question

Does AppSync support nested single mutation?

I want to call a single mutation which will insert records into two tables, eg: User and Roles tables in DynamoDB.

Something like this for example:

createUser(
   input: {
      Name: "John"
      Email: "[email protected]"
      LinesRoles: [
        { Name: "Role 1" }
        { Name: "Role 2" }
      ]
   }) {
        Id
        Name
        LinesRoles {
          Id
          Name
        }
      }

Do I need to create two resolvers in AppSync for User and Roles to insert the records in both tables?

Tinou · Accepted Answer · 2019-05-23 01:42:14Z

3

I can think of three ways to achieve this:

Use a BatchPutItem to save records into two tables at once. However, you won’t be able to use any ConditionExpression
Use a pipeline resolver with two AppSync functions where one function makes a PutItem to the Roles table and the other to the User table. However, you need to be ok with potentially inconsistent scenarios where the record has been inserted in one table but not in the other.
Use a Lambda resolver that does the write to 2 tables inside a DynamoDB transaction.

answered May 23, 2019 at 1:42

Tinou

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2 Comments

user88432 Over a year ago

To use BatchPutItem, how to get new inserted UserId before creating roles in the Roles Table? Do I need 1 or 2 resolvers for this case?

Tinou Over a year ago

When you use BatchPutItem you have to specify the entire item for both tables at the same time. So in your case you need to know the userId before inserting, maybe use a UUID?

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