3b7ed74d11
- examples to fix still
- error_extensions.md ResultExt example does not compile!
- trait ErrorExtensions is not implemented for ParseIntError
- dataloader
- requires sqlx to work. So we either "stub" it OR we rewrite them simpler to use a simple "faux" db library
1.6 KiB
Object
Different from SimpleObject, Object must have a resolver defined for each field in its impl.
A resolver function has to be asynchronous. The first argument has to be &self, the second is an optional Context and it is followed by field arguments.
The resolver is used to get the value of the field. For example, you can query a database and return the result. The return type of the function is the type of the field. You can also return a async_graphql::Result to return an error if it occurs. The error message will then be sent as query result.
You may need access to global data in your query, for example a database connection pool.
When creating your Schema, you can use SchemaBuilder::data to configure the global data, and Context::data to configure Context data.
The following value_from_db function shows how to retrieve a database connection from Context.
# extern crate async_graphql;
# struct Data { pub name: String }
# struct DbConn {}
# impl DbConn {
# fn query_something(&self, id: i64) -> std::result::Result<Data, String> { Ok(Data {name:"".into()})}
# }
# struct DbPool {}
# impl DbPool {
# fn take(&self) -> DbConn { DbConn {} }
# }
use async_graphql::*;
struct MyObject {
value: i32,
}
#[Object]
impl MyObject {
async fn value(&self) -> String {
self.value.to_string()
}
async fn value_from_db(
&self,
ctx: &Context<'_>,
#[graphql(desc = "Id of object")] id: i64
) -> Result<String> {
let conn = ctx.data::<DbPool>()?.take();
Ok(conn.query_something(id)?.name)
}
}