How to access arguments on child resolver from parent call in AWS Appsync - aws-appsync

Question

I have two types: Todo and Comment.
type Todo {
id: ID!
name: String
description: String
priority: Int
status: TodoStatus
comments: [Comment]
}
type Comment {
todoid: ID!
commentid: String!
content: String
}
Then I have a Query getTodo but the thing is I want to include a content arg that filters the comment (child) if the string passed is in the content of Comment.
getTodo(id: ID!, content: String!): Todo
I have tried attaching a resolver to comments (under Todo). If I add a filter here, how will I be able to get the ctx.args.content which was passed in getTodo(id: ID!, content: String!).
{
"version" : "2017-02-28",
"operation" : "Query",
"query" : {
## Provide a query expression. **
"expression": "todoid = :id",
"expressionValues" : {
":id" : {
"S" : "${ctx.args.id}"
}
}
},
"filter": {
"expression": "contains(content, :content)",
"expressionValues" : {
":content": {
"S": "${ctx.args.content}"
}
}
}
}
Or if I remove this filter and leave it like this:
{
"version" : "2017-02-28",
"operation" : "Query",
"query" : {
## Provide a query expression. **
"expression": "todoid = :id",
"expressionValues" : {
":id" : {
"S" : "${ctx.args.id}"
}
}
}
}
How will I modify getTodo Resolver to fetch comments (with content that contains the string passed)?
Can I do it like this (accessing if comments.content contains the content string args passed):
{
"version" : "2017-02-28",
"operation" : "Query",
"query" : {
## Provide a query expression. **
"expression": "id = :id",
"expressionValues" : {
":id" : {
"S" : "${ctx.args.id}"
}
}
},
"filter": {
"expression": "contains(comments.content, :content)",
"expressionValues" : {
":content": {
"S": "${ctx.args.content}"
}
}
}
}

Answer 1

The GraphQL arguments you are accessing via $ctx.args are available at the field level. So when you access them when resolving the Post.comments field, you get back all the arguments on that field and that field only.
So to get the content string argument you could update your Todo type to:
type Todo {
id: ID!
name: String
description: String
priority: Int
status: TodoStatus
comments(content: String): [Comment]
}
Another way, if you don't want to expose the content argument on the Post.comments field and keep the argument on the Query.getTodo field, you could pass the arguments via the source. In your Query.getTodo resolver you could return the content field as part of the todo result. You would then be able to access it inside the Todo.comments resolver via $ctx.source.content.