[−][src]Trait async_graphql::connection::DataSource

pub trait DataSource {
    type CursorType: CursorType + Send + Sync;
    type NodeType: OutputValueType + Send;
    type ConnectionFieldsType: ObjectType + Send;
    type EdgeFieldsType: ObjectType + Send;
#[must_use]    fn execute_query<'life0, 'life1, 'life2, 'async_trait>(
        &'life0 self, 
        ctx: &'life1 Context<'life2>, 
        after: Option<Self::CursorType>, 
        before: Option<Self::CursorType>, 
        first: Option<usize>, 
        last: Option<usize>
    ) -> Pin<Box<dyn Future<Output = FieldResult<Connection<Self::CursorType, Self::NodeType, Self::ConnectionFieldsType, Self::EdgeFieldsType>>> + Send + 'async_trait>>
    where
        'life0: 'async_trait,
        'life1: 'async_trait,
        'life2: 'async_trait,
        Self: 'async_trait;

#[must_use]    fn query<'life0, 'life1, 'life2, 'async_trait>(
        &'life0 self, 
        ctx: &'life1 Context<'life2>, 
        after: Option<String>, 
        before: Option<String>, 
        first: Option<i32>, 
        last: Option<i32>
    ) -> Pin<Box<dyn Future<Output = FieldResult<Connection<Self::CursorType, Self::NodeType, Self::ConnectionFieldsType, Self::EdgeFieldsType>>> + Send + 'async_trait>>
    where
        <Self::CursorType as CursorType>::Error: Display + Send + Sync + 'static,
        'life0: 'async_trait,
        'life1: 'async_trait,
        'life2: 'async_trait,
        Self: Sync + 'async_trait,
    { ... }
}

Data source of GraphQL Cursor Connections type

Edge is an extension object type that extends the edge fields, If you don't need it, you can use EmptyEdgeFields.

References

(GraphQL Cursor Connections Specification)[https://facebook.github.io/relay/graphql/connections.htm]

Examples

use async_graphql::*;
use async_graphql::connection::*;

struct QueryRoot;

struct Numbers;

#[SimpleObject]
struct Diff {
    diff: i32,
}

#[DataSource]
impl DataSource for Numbers {
    type CursorType = usize;
    type NodeType = i32;
    type ConnectionFieldsType = EmptyFields;
    type EdgeFieldsType = Diff;

    async fn execute_query(&self,
        ctx: &Context<'_>,
        after: Option<usize>,
        before: Option<usize>,
        first: Option<usize>,
        last: Option<usize>,
     ) -> FieldResult<Connection<Self::CursorType, Self::NodeType, Self::ConnectionFieldsType, Self::EdgeFieldsType>> {
        let mut start = after.map(|after| after + 1).unwrap_or(0);
        let mut end = before.unwrap_or(10000);
        if let Some(first) = first {
            end = (start + first).min(end);
        }
        if let Some(last) = last {
            start = if last > end - start {
                 end
            } else {
                end - last
            };
        }
        let mut connection = Connection::new(start > 0, end < 10000);
        connection.append(
            (start..end).into_iter().map(|n|
                Ok(Edge::new_with_additional_fields(n, n as i32, Diff{ diff: (10000 - n) as i32 }))),
        )?;
        Ok(connection)
    }
}

#[Object]
impl QueryRoot {
    async fn numbers(&self, ctx: &Context<'_>,
        after: Option<String>,
        before: Option<String>,
        first: Option<i32>,
        last: Option<i32>
    ) -> FieldResult<Connection<usize, i32, EmptyFields, Diff>> {
        Numbers.query(ctx, after, before, first, last).await
    }
}

#[async_std::main]
async fn main() {
    let schema = Schema::new(QueryRoot, EmptyMutation, EmptySubscription);

    assert_eq!(schema.execute("{ numbers(first: 2) { edges { node diff } } }").await.unwrap().data, serde_json::json!({
        "numbers": {
            "edges": [
                {"node": 0, "diff": 10000},
                {"node": 1, "diff": 9999},
            ]
        },
    }));

    assert_eq!(schema.execute("{ numbers(last: 2) { edges { node diff } } }").await.unwrap().data, serde_json::json!({
        "numbers": {
            "edges": [
                {"node": 9998, "diff": 2},
                {"node": 9999, "diff": 1},
            ]
        },
    }));
}

Associated Types

type CursorType: CursorType + Send + Sync

Cursor type

type NodeType: OutputValueType + Send

Record type

type ConnectionFieldsType: ObjectType + Send

Additional fields for connection

Is a type that implements ObjectType and can be defined by the procedure macro #[Object] or #[SimpleObject].

type EdgeFieldsType: ObjectType + Send

Additional fields for edge

Is a type that implements ObjectType and can be defined by the procedure macro #[Object] or #[SimpleObject].

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Required methods

#[must_use]fn execute_query<'life0, 'life1, 'life2, 'async_trait>(
    &'life0 self,
    ctx: &'life1 Context<'life2>,
    after: Option<Self::CursorType>,
    before: Option<Self::CursorType>,
    first: Option<usize>,
    last: Option<usize>
) -> Pin<Box<dyn Future<Output = FieldResult<Connection<Self::CursorType, Self::NodeType, Self::ConnectionFieldsType, Self::EdgeFieldsType>>> + Send + 'async_trait>> where
    'life0: 'async_trait,
    'life1: 'async_trait,
    'life2: 'async_trait,
    Self: 'async_trait, 

Execute query

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Provided methods

#[must_use]fn query<'life0, 'life1, 'life2, 'async_trait>(
    &'life0 self,
    ctx: &'life1 Context<'life2>,
    after: Option<String>,
    before: Option<String>,
    first: Option<i32>,
    last: Option<i32>
) -> Pin<Box<dyn Future<Output = FieldResult<Connection<Self::CursorType, Self::NodeType, Self::ConnectionFieldsType, Self::EdgeFieldsType>>> + Send + 'async_trait>> where
    <Self::CursorType as CursorType>::Error: Display + Send + Sync + 'static,
    'life0: 'async_trait,
    'life1: 'async_trait,
    'life2: 'async_trait,
    Self: Sync + 'async_trait, 

Parses the parameters and executes the query.

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Implementations on Foreign Types

impl<'a, T> DataSource for &'a [T] where
    T: OutputValueType + Send + Sync + 'a, [src]

type CursorType = usize

type NodeType = &'a T

type ConnectionFieldsType = EmptyFields

type EdgeFieldsType = EmptyFields

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Implementors

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