Merge pull request #79 from tomhoule/customize-derives

Let users add arbitrary derives to ResponseData

Author: tomhoule

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 - (breaking) Control over which types custom scalars deserialize to is given to the user: you now have to provide type aliases for the custom scalars in the scope of the struct under derive.
 - (breaking) Support for multi-operations documents. You can select a particular operation by naming the struct under derive after it. In case there is no match, we revert to the current behaviour: select the first operation.
+- Support arbitrary derives on the generated response types via the `response_derives` option on the `graphql` attribute.
 
 ## [0.3.0] - 2018-07-24
 

README.md

@@ -13,6 +13,9 @@ A typed GraphQL client library for Rust.
 - Works in the browser (WebAssembly)
 - Subscriptions support (serialization-deserialization only at the moment)
 - Copies documentation from the GraphQL schema to the generated Rust code
+- Arbitrary derives on the generated responses
+- Arbitrary custom scalars
+- Supports multiple operations per query document
 
 ## Getting started
 
@@ -74,6 +77,31 @@ A typed GraphQL client library for Rust.
 
 [A complete example using the GitHub GraphQL API is available](https://github.com/tomhoule/graphql-client/tree/master/examples/github), as well as sample [rustdoc output](https://www.tomhoule.com/docs/example_module/).
 
+## Deriving specific traits on the response
+
+The generated response types always derive `serde::Deserialize` but you may want to print them (`Debug`), compare them (`PartialEq`) or derive any other trait on it. You can achieve this with the `response_derives` option of the `graphql` attribute. Example:
+
+```rust
+#[derive(GraphQLQuery)]
+#[graphql(
+  schema_path = "src/search_schema.graphql",
+  query_path = "src/search_query.graphql"
+  query_path = "src/search_query.graphql",
+  response_derives = "Serialize,PartialEq",
+)]
+struct SearchQuery;
+```
+
+## Custom scalars
+
+The generated code will reference the scalar types as defined in the server schema. This means you have to provide matching rust types in the scope of the struct under derive. It can be as simple as declarations like `type Email = String;`. This gives you complete freedom on how to treat custom scalars, as long as they can be deserialized.
+
+## Query documents with multiple operations
+
+You can write multiple operations in one query document (one `.graphql` file). You can then select one by naming the struct you `#[derive(GraphQLQuery)]` on with the same name as one of the operations. This is neat, as it allows sharing fragments between operations.
+
+There is an example [in the tests](./tests/operation_selection).
+
 ## Examples
 
 See the examples directory in this repository.

examples/example_module/src/lib.rs

@@ -11,6 +11,7 @@ use custom_scalars::*;
 #[derive(GraphQLQuery)]
 #[graphql(
     schema_path = "../github/src/schema.graphql",
-    query_path = "../github/src/query_1.graphql"
+    query_path = "../github/src/query_1.graphql",
+    response_derives = "Debug",
 )]
 pub struct ExampleModule;

examples/github/src/main.rs

@@ -32,7 +32,8 @@ type DateTime = String;
 #[derive(GraphQLQuery)]
 #[graphql(
     schema_path = "src/schema.graphql",
-    query_path = "src/query_1.graphql"
+    query_path = "src/query_1.graphql",
+    response_derives = "Debug",
 )]
 struct Query1;
 

graphql_client_cli/src/main.rs

@@ -15,7 +15,8 @@ use structopt::StructOpt;
 #[derive(GraphQLQuery)]
 #[graphql(
     schema_path = "src/introspection_schema.graphql",
-    query_path = "src/introspection_query.graphql"
+    query_path = "src/introspection_query.graphql",
+    response_derives = "Serialize",
 )]
 struct IntrospectionQuery;
 

graphql_query_derive/src/attributes.rs

@@ -0,0 +1,29 @@
+use failure;
+use syn;
+
+pub(crate) fn extract_attr(ast: &syn::DeriveInput, attr: &str) -> Result<String, failure::Error> {
+    let attributes = &ast.attrs;
+    let attribute = attributes
+        .iter()
+        .find(|attr| {
+            let path = &attr.path;
+            quote!(#path).to_string() == "graphql"
+        }).ok_or_else(|| format_err!("The graphql attribute is missing"))?;
+    if let syn::Meta::List(items) = &attribute
+        .interpret_meta()
+        .expect("Attribute is well formatted")
+    {
+        for item in items.nested.iter() {
+            if let syn::NestedMeta::Meta(syn::Meta::NameValue(name_value)) = item {
+                let syn::MetaNameValue { ident, lit, .. } = name_value;
+                if ident == attr {
+                    if let syn::Lit::Str(lit) = lit {
+                        return Ok(lit.value());
+                    }
+                }
+            }
+        }
+    }
+
+    Err(format_err!("attribute not found"))?
+}

graphql_query_derive/src/codegen.rs

@@ -11,8 +11,14 @@ pub(crate) fn response_for_query(
     schema: schema::Schema,
     query: query::Document,
     selected_operation: String,
+    additional_derives: Option<String>,
 ) -> Result<TokenStream, failure::Error> {
     let mut context = QueryContext::new(schema);
+
+    if let Some(derives) = additional_derives {
+        context.ingest_additional_derives(&derives).unwrap();
+    }
+
     let mut definitions = Vec::new();
     let mut operations: Vec<Operation> = Vec::new();
 
@@ -77,7 +83,11 @@ pub(crate) fn response_for_query(
             .unwrap()
     };
 
-    let enum_definitions = context.schema.enums.values().map(|enm| enm.to_rust());
+    let enum_definitions = context
+        .schema
+        .enums
+        .values()
+        .map(|enm| enm.to_rust(&context));
     let fragment_definitions: Result<Vec<TokenStream>, _> = context
         .fragments
         .values()
@@ -101,6 +111,8 @@ pub(crate) fn response_for_query(
         .map(|s| s.to_rust())
         .collect();
 
+    let response_derives = context.response_derives();
+
     Ok(quote! {
         type Boolean = bool;
         type Float = f64;
@@ -119,7 +131,7 @@ pub(crate) fn response_for_query(
 
         #variables_struct
 
-        #[derive(Debug, Serialize, Deserialize)]
+        #response_derives
         #[serde(rename_all = "camelCase")]
         pub struct ResponseData {
             #(#response_data_fields,)*

graphql_query_derive/src/enums.rs

@@ -16,7 +16,8 @@ pub struct GqlEnum {
 }
 
 impl GqlEnum {
-    pub fn to_rust(&self) -> TokenStream {
+    pub(crate) fn to_rust(&self, query_context: &::query::QueryContext) -> TokenStream {
+        let derives = query_context.response_enum_derives();
         let variant_names: Vec<TokenStream> = self
             .variants
             .iter()
@@ -42,7 +43,7 @@ impl GqlEnum {
         let name = name_ident.clone();
 
         quote! {
-            #[derive(Debug)]
+            #derives
             pub enum #name {
                 #(#variant_names,)*
                 Other(String),

graphql_query_derive/src/fragments.rs

@@ -11,13 +11,14 @@ pub struct GqlFragment {
 
 impl GqlFragment {
     pub(crate) fn to_rust(&self, context: &QueryContext) -> Result<TokenStream, ::failure::Error> {
+        let derives = context.response_derives();
         let name_ident = Ident::new(&self.name, Span::call_site());
         let object = context.schema.objects.get(&self.on).expect("oh, noes");
         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!{
-            #[derive(Debug, Deserialize, Serialize)]
+            #derives
             pub struct #name_ident {
                 #(#fields,)*
             }

graphql_query_derive/src/interfaces.rs

@@ -33,6 +33,7 @@ impl GqlInterface {
         prefix: &str,
     ) -> Result<TokenStream, failure::Error> {
         let name = Ident::new(&prefix, Span::call_site());
+        let derives = query_context.response_derives();
 
         selection
             .extract_typename()
@@ -78,13 +79,13 @@ impl GqlInterface {
         let attached_enum_name = Ident::new(&format!("{}On", name), Span::call_site());
         let (attached_enum, last_object_field) = if !union_variants.is_empty() {
             let attached_enum = quote! {
-                #[derive(Deserialize, Debug, Serialize)]
+                #derives
                 #[serde(tag = "__typename")]
                 pub enum #attached_enum_name {
                     #(#union_variants,)*
                 }
             };
-            let last_object_field = quote!(#[serde(flatten)] on: #attached_enum_name,);
+            let last_object_field = quote!(#[serde(flatten)] pub on: #attached_enum_name,);
             (attached_enum, last_object_field)
         } else {
             (quote!(), quote!())
@@ -98,7 +99,7 @@ impl GqlInterface {
 
             #attached_enum
 
-            #[derive(Debug, Serialize, Deserialize)]
+            #derives
             pub struct #name {
                 #(#object_fields,)*
                 #last_object_field

graphql_query_derive/src/lib.rs

@@ -1,4 +1,4 @@
-#![recursion_limit = "128"]
+#![recursion_limit = "512"]
 
 #[macro_use]
 extern crate failure;
@@ -16,6 +16,7 @@ extern crate quote;
 
 use proc_macro2::TokenStream;
 
+mod attributes;
 mod codegen;
 mod constants;
 mod enums;
@@ -77,8 +78,9 @@ fn impl_gql_query(input: &syn::DeriveInput) -> Result<TokenStream, failure::Erro
     let cargo_manifest_dir =
         ::std::env::var("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR env variable is defined");
 
-    let query_path = extract_attr(input, "query_path")?;
-    let schema_path = extract_attr(input, "schema_path")?;
+    let query_path = attributes::extract_attr(input, "query_path")?;
+    let schema_path = attributes::extract_attr(input, "schema_path")?;
+    let response_derives = attributes::extract_attr(input, "response_derives").ok();
 
     // We need to qualify the query with the path to the crate it is part of
     let query_path = format!("{}/{}", cargo_manifest_dir, query_path);
@@ -108,7 +110,8 @@ fn impl_gql_query(input: &syn::DeriveInput) -> Result<TokenStream, failure::Erro
 
     let module_name = Ident::new(&input.ident.to_string().to_snake_case(), Span::call_site());
     let struct_name = &input.ident;
-    let schema_output = codegen::response_for_query(schema, query, input.ident.to_string())?;
+    let schema_output =
+        codegen::response_for_query(schema, query, input.ident.to_string(), response_derives)?;
 
     let result = quote!(
         pub mod #module_name {
@@ -139,30 +142,3 @@ fn impl_gql_query(input: &syn::DeriveInput) -> Result<TokenStream, failure::Erro
 
     Ok(result)
 }
-
-fn extract_attr(ast: &syn::DeriveInput, attr: &str) -> Result<String, failure::Error> {
-    let attributes = &ast.attrs;
-    let attribute = attributes
-        .iter()
-        .find(|attr| {
-            let path = &attr.path;
-            quote!(#path).to_string() == "graphql"
-        }).ok_or_else(|| format_err!("The graphql attribute is missing"))?;
-    if let syn::Meta::List(items) = &attribute
-        .interpret_meta()
-        .expect("Attribute is well formatted")
-    {
-        for item in items.nested.iter() {
-            if let syn::NestedMeta::Meta(syn::Meta::NameValue(name_value)) = item {
-                let syn::MetaNameValue { ident, lit, .. } = name_value;
-                if ident == attr {
-                    if let syn::Lit::Str(lit) = lit {
-                        return Ok(lit.value());
-                    }
-                }
-            }
-        }
-    }
-
-    Err(format_err!("attribute not found"))?
-}

graphql_query_derive/src/objects.rs

@@ -67,14 +67,15 @@ impl GqlObject {
         selection: &Selection,
         prefix: &str,
     ) -> Result<TokenStream, failure::Error> {
+        let derives = query_context.response_derives();
         let name = Ident::new(prefix, Span::call_site());
         let fields = self.response_fields_for_selection(query_context, selection, prefix)?;
         let field_impls = self.field_impls_for_selection(query_context, selection, &prefix)?;
         let description = self.description.as_ref().map(|desc| quote!(#[doc = #desc]));
         Ok(quote! {
             #(#field_impls)*
 
-            #[derive(Debug, Serialize, Deserialize)]
+            #derives
             #[serde(rename_all = "camelCase")]
             #description
             pub struct #name {