Implement fragment on interfaces

This is limited to the interface’s own fields for now. We do not support type-refining fragments (see this issue: #154).

Author: tomhoule

.gitignore

@@ -1,4 +1,4 @@
-/target
+target/
 node_modules/
 **/*.rs.bk
 Cargo.lock

CHANGELOG.md

@@ -52,6 +52,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 - `GraphQLError` now implements the `Display` trait.
 
+- Basic support for fragments on interfaces
+
 ### Fixed
 
 - Handle all Rust keywords as field names in codegen by appending `_` to the generated names, so a field called `type` in a GraphQL query will become a `type_` field in the generated struct. Thanks to @scrogson!

examples/call_from_js/src/lib.rs

@@ -1,4 +1,4 @@
-#![feature(wasm_custom_section, wasm_import_module, use_extern_macros)]
+#![feature(use_extern_macros)]
 
 #[macro_use]
 extern crate graphql_client;

graphql_client_codegen/src/fragments.rs

@@ -16,16 +16,24 @@ impl GqlFragment {
         let derives = context.response_derives();
         let name_ident = Ident::new(&self.name, Span::call_site());
         let opt_object = context.schema.objects.get(&self.on);
-        let object = if let Some(object) = opt_object {
-            object
+        let (field_impls, fields) = if let Some(object) = opt_object {
+            let field_impls =
+                object.field_impls_for_selection(context, &self.selection, &self.name)?;
+            let fields =
+                object.response_fields_for_selection(context, &self.selection, &self.name)?;
+            (field_impls, fields)
+        } else if let Some(iface) = context.schema.interfaces.get(&self.on) {
+            let field_impls =
+                iface.field_impls_for_selection(context, &self.selection, &self.name)?;
+            let fields =
+                iface.response_fields_for_selection(context, &self.selection, &self.name)?;
+            (field_impls, fields)
         } else {
             panic!(
                 "fragment '{}' cannot operate on unknown type '{}'",
                 self.name, self.on
             );
         };
-        let field_impls = object.field_impls_for_selection(context, &self.selection, &self.name)?;
-        let fields = object.response_fields_for_selection(context, &self.selection, &self.name)?;
 
         Ok(quote!{
             #derives

graphql_client_codegen/src/interfaces.rs

@@ -19,7 +19,22 @@ pub struct GqlInterface {
 }
 
 impl GqlInterface {
-    pub fn new(name: Cow<str>, description: Option<&str>) -> GqlInterface {
+    fn object_selection(&self, selection: &Selection) -> Selection {
+        Selection(
+            selection
+                .0
+                .iter()
+                // Only keep what we can handle
+                .filter(|f| match f {
+                    SelectionItem::Field(f) => f.name != "__typename",
+                    SelectionItem::FragmentSpread(_) => true,
+                    SelectionItem::InlineFragment(_) => false,
+                }).map(|a| (*a).clone())
+                .collect(),
+        )
+    }
+
+    pub(crate) fn new(name: Cow<str>, description: Option<&str>) -> GqlInterface {
         GqlInterface {
             description: description.map(|d| d.to_owned()),
             name: name.into_owned(),
@@ -29,6 +44,35 @@ impl GqlInterface {
         }
     }
 
+    pub(crate) fn field_impls_for_selection(
+        &self,
+        context: &QueryContext,
+        selection: &Selection,
+        prefix: &str,
+    ) -> Result<Vec<TokenStream>, failure::Error> {
+        ::shared::field_impls_for_selection(
+            &self.fields,
+            context,
+            &self.object_selection(selection),
+            prefix,
+        )
+    }
+
+    pub(crate) fn response_fields_for_selection(
+        &self,
+        context: &QueryContext,
+        selection: &Selection,
+        prefix: &str,
+    ) -> Result<Vec<TokenStream>, failure::Error> {
+        response_fields_for_selection(
+            &self.name,
+            &self.fields,
+            context,
+            &self.object_selection(selection),
+            prefix,
+        )
+    }
+
     pub(crate) fn response_for_selection(
         &self,
         query_context: &QueryContext,
@@ -42,19 +86,6 @@ impl GqlInterface {
             .extract_typename()
             .ok_or_else(|| format_err!("Missing __typename in selection for {}", prefix))?;
 
-        let object_selection = Selection(
-            selection
-                .0
-                .iter()
-                // Only keep what we can handle
-                .filter(|f| match f {
-                    SelectionItem::Field(f) => f.name != "__typename",
-                    SelectionItem::FragmentSpread(_) => true,
-                    SelectionItem::InlineFragment(_) => false,
-                }).map(|a| (*a).clone())
-                .collect(),
-        );
-
         let union_selection = Selection(
             selection
                 .0
@@ -67,16 +98,10 @@ impl GqlInterface {
                 .collect(),
         );
 
-        let object_fields = response_fields_for_selection(
-            &self.name,
-            &self.fields,
-            query_context,
-            &object_selection,
-            prefix,
-        )?;
+        let object_fields =
+            self.response_fields_for_selection(query_context, &selection, prefix)?;
 
-        let object_children =
-            field_impls_for_selection(&self.fields, query_context, &object_selection, prefix)?;
+        let object_children = self.field_impls_for_selection(query_context, &selection, prefix)?;
         let (mut union_variants, union_children, used_variants) =
             union_variants(&union_selection, query_context, prefix)?;
 

tests/interfaces.rs

@@ -84,7 +84,7 @@ fn interface_not_on_everything_deserialization() {
 #[graphql(
     query_path = "tests/interfaces/interface_with_fragment_query.graphql",
     schema_path = "tests/interfaces/interface_schema.graphql",
-    response_derives = "Debug",
+    response_derives = "Debug,PartialEq",
 )]
 pub struct InterfaceWithFragmentQuery;
 
@@ -93,6 +93,45 @@ const RESPONSE_FRAGMENT: &'static str =
 
 #[test]
 fn fragment_in_interface() {
+    use interface_with_fragment_query::*;
     let response_data: interface_with_fragment_query::ResponseData =
-        serde_json::from_str(RESPONSE_FRAGMENT).unwrap();
+        serde_json::from_str(RESPONSE_FRAGMENT).expect("RESPONSE_FRAGMENT did not deserialize");
+
+    assert_eq!(
+        response_data,
+        ResponseData {
+            everything: Some(vec![
+                RustMyQueryEverything {
+                    name: "Audrey Lorde".to_string(),
+                    public_status: PublicStatus {
+                        display_name: false,
+                    },
+                    on: RustMyQueryEverythingOn::Person(RustMyQueryEverythingOnPerson {
+                        birthday: Some("1934-02-18".to_string()),
+                    })
+                },
+                RustMyQueryEverything {
+                    name: "Laïka".to_string(),
+                    public_status: PublicStatus { display_name: true },
+                    on: RustMyQueryEverythingOn::Dog(RustMyQueryEverythingOnDog {
+                        is_good_dog: true,
+                    })
+                },
+                RustMyQueryEverything {
+                    name: "Mozilla".to_string(),
+                    public_status: PublicStatus {
+                        display_name: false
+                    },
+                    on: RustMyQueryEverythingOn::Organization,
+                },
+                RustMyQueryEverything {
+                    name: "Norbert".to_string(),
+                    public_status: PublicStatus { display_name: true },
+                    on: RustMyQueryEverythingOn::Dog(RustMyQueryEverythingOnDog {
+                        is_good_dog: true
+                    }),
+                },
+            ])
+        }
+    )
 }

tests/interfaces/interface_with_fragment_query.graphql

@@ -1,20 +1,17 @@
 fragment PublicStatus on Named {
-    displayName
+  displayName
 }
 
 query MyQuery {
-    everything {
-        name
-        __typename
-        ...PublicStatus
-        ... on Dog {
-            isGoodDog
-        }
-        ... on Person {
-            birthday
-        }
-        ... on Organization {
-            industry
-        }
+  everything {
+    name
+    __typename
+    ...PublicStatus
+    ... on Dog {
+      isGoodDog
     }
+    ... on Person {
+      birthday
+    }
+  }
 }

tests/interfaces/interface_with_fragment_response.json

@@ -15,8 +15,7 @@
         {
             "__typename": "Organization",
             "name": "Mozilla",
-            "displayName": false,
-            "industry": "OTHER"
+            "displayName": false
         },
         {
             "__typename": "Dog",