feat: support batch queries

graphql_client/src/lib.rs

@@ -86,6 +86,8 @@ pub trait GraphQLQuery {
 
     /// Produce a GraphQL query struct that can be JSON serialized and sent to a GraphQL API.
     fn build_query(variables: Self::Variables) -> QueryBody<Self::Variables>;
+    /// Produce a GraphQL batch query struct that can be JSON serialized and sent to a GraphQL API.
+    fn build_batch_query(variables: Vec<Self::Variables>) -> Vec<QueryBody<Self::Variables>>;
 }
 
 /// The form in which queries are sent over HTTP in most implementations. This will be built using the [`GraphQLQuery`] trait normally.

graphql_client/src/reqwest.rs

@@ -16,6 +16,19 @@ pub async fn post_graphql<Q: GraphQLQuery, U: reqwest::IntoUrl>(
     reqwest_response.json().await
 }
 
+/// Use the provided reqwest::Client to post a GraphQL request.
+#[cfg(any(feature = "reqwest", feature = "reqwest-rustls"))]
+pub async fn post_graphql_batch<Q: GraphQLQuery, U: reqwest::IntoUrl>(
+    client: &reqwest::Client,
+    url: U,
+    variables: Vec<Q::Variables>,
+) -> Result<crate::Response<Q::ResponseData>, reqwest::Error> {
+    let body = Q::build_batch_query(variables);
+    let reqwest_response = client.post(url).json(&body).send().await?;
+
+    reqwest_response.json().await
+}
+
 /// Use the provided reqwest::Client to post a GraphQL request.
 #[cfg(feature = "reqwest-blocking")]
 pub fn post_graphql_blocking<Q: GraphQLQuery, U: reqwest::IntoUrl>(
@@ -28,3 +41,16 @@ pub fn post_graphql_blocking<Q: GraphQLQuery, U: reqwest::IntoUrl>(
 
     reqwest_response.json()
 }
+
+/// Use the provided reqwest::Client to post a GraphQL request.
+#[cfg(feature = "reqwest-blocking")]
+pub fn post_graphql_blocking_batch<Q: GraphQLQuery, U: reqwest::IntoUrl>(
+    client: &reqwest::blocking::Client,
+    url: U,
+    variables: Vec<Q::Variables>,
+) -> Result<crate::Response<Q::ResponseData>, reqwest::Error> {
+    let body = Q::build_batch_query(variables);
+    let reqwest_response = client.post(url).json(&body).send()?;
+
+    reqwest_response.json()
+}

graphql_client/tests/batch_queries.rs

@@ -0,0 +1,28 @@
+use graphql_client::*;
+
+#[derive(GraphQLQuery)]
+#[graphql(
+    query_path = "tests/operation_selection/queries.graphql",
+    schema_path = "tests/operation_selection/schema.graphql",
+    response_derives = "Debug, PartialEq, Eq"
+)]
+pub struct Echo;
+
+#[test]
+fn batch_query() {
+    let echo_variables = vec![
+        echo::Variables {
+            msg: Some("hi".to_string()),
+        },
+        echo::Variables {
+            msg: Some("hello".to_string()),
+        },
+    ];
+    let echo_batch_queries: serde_json::Value =
+        serde_json::to_value(Echo::build_batch_query(echo_variables))
+            .expect("Failed to serialize the query!");
+    assert_eq!(
+        echo_batch_queries.to_string(),
+        r#"[{"operationName":"Echo","query":"query Heights($buildingId: ID!, $mountainName: String) {\n  mountainHeight(name: $mountainName)\n  buildingHeight(id: $buildingId)\n}\n\nquery Echo($msg: String) {\n  echo(msg: $msg)\n}\n","variables":{"msg":"hi"}},{"operationName":"Echo","query":"query Heights($buildingId: ID!, $mountainName: String) {\n  mountainHeight(name: $mountainName)\n  buildingHeight(id: $buildingId)\n}\n\nquery Echo($msg: String) {\n  echo(msg: $msg)\n}\n","variables":{"msg":"hello"}}]"#
+    );
+}