How can I return a map using dynamic -graphql

[shivam-880]

Following code complain with compilation error:

#[ResolvedObjectFields]
impl Node {
    async fn properties<'a>(&self, _ctx: &Context<'a>) -> HashMap<String, Foo> {
        HashMap::<String, Foo>::new()
    }

Error:

the trait bound `HashMap<std::string::String, Foo>: Register` is not satisfied [E0277] 
the trait `Register` is not implemented for `HashMap<std::string::String, Foo>` Help: 
the following other types implement trait `Register`:

How do I implement Register for HashMap? And how can I make it generic so that I don't end up reimplmenting Register for each hashmaps?

[smmoosavi]

What is the expected graphql type in the schema? did you want to have a Json scalar type?

[shivam-880]

yes

[smmoosavi]

You can define a new scalar with Scalar macro and implementing ScalarValue trait

use dynamic_graphql::{Value, Scalar, ScalarValue};

#[derive(Scalar)]
#[graphql(name = "Json")]
pub struct JsonScalar(pub HashMap::<String, Value>);

impl ScalarValue for JsonScalar {
    fn from_value(value: Value) -> dynamic_graphql::Result<Self>
    where
        Self: Sized,
    {
        todo!();
    }

    fn to_value(&self) -> Value {
        todo!();
    }
}

see this file for more examples.

[shivam-880]

I believe this is what you are suggesting.

#[derive(Serialize, Deserialize, Scalar)]
pub struct IP {
    key: String,
    value: IpAddr
}

impl ScalarValue for IP {
    fn from_value(value: Value) -> dynamic_graphql::Result<Self>
    where
        Self: Sized,
    {
        match value {
            Value::String(s) => Ok(serde_json::from_str(&s).unwrap()),
            _ => Err(dynamic_graphql::Error::new(
                "Expected a string value".to_string(),
            )),
        }
    }

    fn to_value(&self) -> Value {
        serde_json::to_string(self).unwrap().into()
    }
}

Could be used as:

IP{key: "address1".to_string(), value:IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1))}

[smmoosavi]

No. As I know Scalar could be any value, not just string.

can you provide a sample graphql schema, query, and the response you need?

[smmoosavi]

I added examples for JsonValue, JsonObject, and KeyValue scalar in #24. Hope it helps!