graphql variables serialize as a string and not json

[softprops]

Summary

when hurl constructs a request from a graphql query containing variables it correctly generates a json both with "query" and "variables" keys however the value assigned to "variables" is serialized as a string and not as a json object as most graphql servers expect

POST https://example.org/starwars/graphql
```graphql
query Hero($episode: Episode, $withFriends: Boolean!) {
  hero(episode: $episode) {
    name
    friends @include(if: $withFriends) {
      name
    }
  }
}

variables {
  "episode": "JEDI",
  "withFriends": false
}
```

Steps to reproduce

use the graphql example from the readme and run hurl with the --verbose flag capturing the curl example it generates

curl -H 'Content-Type: application/json' --data '{"query":"query Hero($episode: Episode, $withFriends: Boolean!) {\n  hero(episode: $episode) {\n    name\n    friends @include(if: $withFriends) {\n      name\n    }\n  }\n}","variables":"{\n  \"episode\": \"JEDI\",\n  \"withFriends\": false\n}"}' 'https://example.org/starwars/graphql'

note how "variables" is a string and not json "variables":"{\n \"episode\": \"JEDI\",\n \"withFriends\": false\n}"

Example Project

What is the current bug behavior?

"variables" objects in json encoded requests is a string

What is the expected correct behavior?

most servers will expect "variables" as a json object something more like this "variables":{ "episode": "JEDI", "withFriends": false}

this is also what is described by graphql.org https://graphql.org/learn/serving-over-http/#post-request

Relevant logs and/or screenshots

Output of checks

• Version (hurl --version):

hurl 2.0.0 libcurl/7.77.0 (SecureTransport) LibreSSL/2.8.3 zlib/1.2.11 nghttp2/1.42.0
Features (libcurl):  alt-svc AsynchDNS HSTS HTTP2 IPv6 Largefile libz NTLM NTLM_WB SPNEGO SSL UnixSockets
Features (built-in): brotli

• Operating system and version:

osx

Possible fixes

[jcamiel]

Good catch and thanks for the detailed issue. We will try to do a quick patch asap.

[softprops]

@jcamiel thanks and btw, this tool is awesome. My company is going to be looking to invest in usage of this tool for our e2e testing story. So far this looks perfect.

I'm not technically blocked on this issue as I'm able to gracefully degrade back to json requests

GET http://localhost:8080
ApolloGraphql-Client-Name: hurl-test
[Options]
retry: true
{
  "query": "query testMember($id: ID!) { member(id: $id) { name } }",
  "variables": { "id": "{{member_id}}" },
  "operationName": "testMember"
}

HTTP/1.1 200
[Asserts]
jsonpath "$.data.member" exists
duration < 200

but having the new native gql support will make for a much nicer authoring experience for our engineers

[jcamiel]

@softprops would you be kind to test my fix on this branch https://github.com/Orange-OpenSource/hurl/tree/1218-graphql-variables-serialize-as-a-string-and-not-json master? You'll need to build Hurl (see https://hurl.dev/docs/installation.html#building-from-sources)
No obligation of course, only if you can and have some time! I'm not a GraphQL expert, I want to be sure that variables are ok this time.

[softprops]

@jcamiel worked like a charm!

POST http://localhost:8080
ApolloGraphql-Client-Name: hurl-test
[Options]
retry: true
```graphql
query testMember($id: ID!) {
  member(id: $id) {
    name
  }
}

variables {
  "id": "{{member_id}}"
}
```

path/to/hurl/target/release/hurl --verbose	 --test --glob "src/e2e-test/**/*.hurl" --variable member_id=xxx

<snip>
*
* Request can be run with the following curl command:
* curl -H 'ApolloGraphql-Client-Name: hurl-test' -H 'Content-Type: application/json' --data '{"query":"query testMember($id: ID!) {\n  member(id: $id) {\n    name\n  }\n}","variables":{"id":"xxx"}}' 'http://localhost:8080'
<snip>

[softprops]

I'll keep an eye out for the next release. Thanks!

[jcamiel]

@softprops We've released a 2.0.1, should be available on the various packet managers soon