Appsync mutatation query giving MalformedHttpRequestException via POST - graphql

Question

I am trying out the default example for realtime updates on AWS appsync.
Schema
type Channel {
name: String!
data: AWSJSON!
}
type Mutation {
publish(name: String!, data: AWSJSON!): Channel
}
type Query {
getChannel: Channel
}
type Subscription {
subscribe(name: String!): Channel
#aws_subscribe(mutations: ["publish"])
}
Running this query through AWS query page gives success
mutation PublishData {
publish(data: "{\"msg\": \"hello world!\"}", name: "channel") {
data
name
}
}
When trying to execute the same through HTTP Post, it gives error.
curl --location --request POST 'https://XXXX.ap-south-1.amazonaws.com:443/graphql' \
--header 'x-api-key: XXXXX' \
--header 'Content-Type: application/graphql' \
--data-raw '{
"query": "mutation PublishData { publish(data: \"{\"msg\": \"hello world!\"}\", name: \"broadcast\") { data name } }",
"variables": "{}"
}'
Executing this query gives success
curl --location --request POST 'https://XXX.ap-south-1.amazonaws.com:443/graphql' \
--header 'x-api-key: XXXX' \
--header 'Content-Type: application/graphql' \
--data-raw '{
"query": "mutation PublishData { publish(data: \"{}\", name: \"broadcast\") { data name } }",
"variables": "{}"
}'
I am unable to figure out where is the syntax error.

Answer 1

I got it working using variables. This is the syntax.
{
"query": "mutation($data:AWSJSON!) { publish(data: $data, name: \"broadcast\") { data name } }",
"variables": {"data":"{\"abs\":1}"}
}