1.0 KiB
1.0 KiB
Custom scalars
In Async-GraphQL
most common scalar types are built in, but you can also create your own scalar types.
Using async-graphql::Scalar
, you can add support for a scalar when you implement it. You only need to implement parsing and output functions.
The following example defines a 64-bit integer scalar where its input and output are strings. (Note: Async-graphQL
already supports 64-bit integers and uses strings as input and output.)
use async_graphql::*;
struct StringNumber(i64);
#[Scalar]
impl ScalarType for StringNumber {
fn type_name() -> &'static str {
// Name of type
"StringNumber"
}
fn parse(value: &Value) -> Option<Self> {
if let Value::String(value) = value {
// Parse the integer value
value.parse().ok().map(StringNumber)
} else {
// If the type does not match, return None
None
}
}
fn to_json(&self) -> Result<serde_json::Value> {
Ok(serde_json::to_value(self.0).unwrap())
}
}