Allow using #[derive(GraphQLQuery)] without depending on serde

This PR makes the serde derives emitted by `#[derive(GraphQLQuery)]` use
a private re-export of the serde crate instead of relying on users of
this crate having added serde to their `Cargo.toml`.

Serde allows you to add an annotation

    #[serde(crate = "<path to crate>")]

for exactly this reason so most of this PR is just plumbing the correct
path through the codegen crate to the correct annotation.

Details
-------
- There is a new `#[doc(hidden)] mod _private` declaration in the
  `graphql_client` crate. All re-exports (which is just serde) have been
   placed there.
- I have added a new `serde_path` field to `GraphQLCodegenOptions` which
  defaults to `::serde`. This means that the code generated by the CLI
  should remain effectively unchanged.
- The rest is just applying `#[serde(crate = ...)]` annotations where
  appropriate.

Fixes #427

examples/github/Cargo.toml

@@ -7,7 +7,6 @@ edition = "2018"
 [dev-dependencies]
 anyhow = "1.0"
 graphql_client = { path = "../../graphql_client", features = ["reqwest-blocking"] }
-serde = "^1.0"
 reqwest = { version = "^0.11", features = ["json", "blocking"] }
 prettytable-rs = "^0.7"
 clap = { version = "^3.0", features = ["derive"] }

examples/hasura/Cargo.toml

@@ -7,7 +7,6 @@ edition = "2018"
 [dev-dependencies]
 anyhow = "1.0"
 graphql_client = { path = "../../graphql_client", features = ["reqwest-blocking"] }
-serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 reqwest = { version = "^0.11", features = ["json", "blocking"] }
 prettytable-rs = "0.7.0"

examples/web/Cargo.toml

@@ -10,7 +10,6 @@ crate-type = ["cdylib", "rlib"]
 [dependencies]
 graphql_client = { path = "../../graphql_client", features = ["reqwest"] }
 wasm-bindgen = "^0.2"
-serde = { version = "1.0.67", features = ["derive"] }
 lazy_static = "1.0.1"
 js-sys = "0.3.6"
 wasm-bindgen-futures = "0.4.18"

graphql_client/src/lib.rs

@@ -299,6 +299,12 @@ pub struct Response<Data> {
     pub extensions: Option<HashMap<String, serde_json::Value>>,
 }
 
+/// Hidden module for types used by the codegen crate.
+#[doc(hidden)]
+pub mod _private {
+    pub use ::serde;
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

graphql_client_codegen/src/codegen.rs

@@ -11,7 +11,7 @@ use crate::{
 };
 use heck::ToSnakeCase;
 use proc_macro2::{Ident, Span, TokenStream};
-use quote::quote;
+use quote::{quote, ToTokens};
 use selection::*;
 use std::collections::BTreeMap;
 
@@ -21,6 +21,8 @@ pub(crate) fn response_for_query(
     options: &GraphQLClientCodegenOptions,
     query: BoundQuery<'_>,
 ) -> Result<TokenStream, GeneralError> {
+    let serde = options.serde_path();
+
     let all_used_types = all_used_types(operation_id, &query);
     let response_derives = render_derives(options.all_response_derives());
     let variable_derives = render_derives(options.all_variable_derives());
@@ -43,7 +45,7 @@ pub(crate) fn response_for_query(
         render_response_data_fields(operation_id, options, &query).render(&response_derives);
 
     let q = quote! {
-        use serde::{Serialize, Deserialize};
+        use #serde::{Serialize, Deserialize};
         use super::*;
 
         #[allow(dead_code)]
@@ -77,9 +79,13 @@ fn generate_variables_struct(
     options: &GraphQLClientCodegenOptions,
     query: &BoundQuery<'_>,
 ) -> TokenStream {
+    let serde = options.serde_path();
+    let serde_path = serde.to_token_stream().to_string();
+
     if operation_has_no_variables(operation_id, query.query) {
         return quote!(
             #variable_derives
+            #[serde(crate = #serde_path)]
             pub struct Variables;
         );
     }
@@ -115,6 +121,7 @@ fn generate_variables_struct(
 
     let variables_struct = quote!(
         #variable_derives
+        #[serde(crate = #serde_path)]
         pub struct Variables {
             #(#variable_fields,)*
         }

graphql_client_codegen/src/codegen/enums.rs

@@ -16,6 +16,7 @@ pub(super) fn generate_enum_definitions<'a, 'schema: 'a>(
     options: &'a GraphQLClientCodegenOptions,
     query: BoundQuery<'schema>,
 ) -> impl Iterator<Item = TokenStream> + 'a {
+    let serde = options.serde_path();
     let traits = options
         .all_response_derives()
         .chain(options.all_variable_derives())
@@ -66,18 +67,18 @@ pub(super) fn generate_enum_definitions<'a, 'schema: 'a>(
                 Other(String),
             }
 
-            impl ::serde::Serialize for #name {
-                fn serialize<S: serde::Serializer>(&self, ser: S) -> Result<S::Ok, S::Error> {
+            impl #serde::Serialize for #name {
+                fn serialize<S: #serde::Serializer>(&self, ser: S) -> Result<S::Ok, S::Error> {
                     ser.serialize_str(match *self {
                         #(#constructors => #variant_str,)*
                         #name::Other(ref s) => &s,
                     })
                 }
             }
 
-            impl<'de> ::serde::Deserialize<'de> for #name {
-                fn deserialize<D: ::serde::Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
-                    let s: String = ::serde::Deserialize::deserialize(deserializer)?;
+            impl<'de> #serde::Deserialize<'de> for #name {
+                fn deserialize<D: #serde::Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
+                    let s: String = #serde::Deserialize::deserialize(deserializer)?;
 
                     match s.as_str() {
                         #(#variant_str => Ok(#constructors),)*

graphql_client_codegen/src/codegen/inputs.rs

@@ -7,7 +7,7 @@ use crate::{
 };
 use heck::{ToSnakeCase, ToUpperCamelCase};
 use proc_macro2::{Ident, Span, TokenStream};
-use quote::quote;
+use quote::{quote, ToTokens};
 
 pub(super) fn generate_input_object_definitions(
     all_used_types: &UsedTypes,
@@ -33,6 +33,9 @@ fn generate_struct(
     variable_derives: &impl quote::ToTokens,
     query: &BoundQuery<'_>,
 ) -> TokenStream {
+    let serde = options.serde_path();
+    let serde_path = serde.to_token_stream().to_string();
+
     let normalized_name = options.normalization().input_name(input.name.as_str());
     let safe_name = keyword_replace(normalized_name);
     let struct_name = Ident::new(safe_name.as_ref(), Span::call_site());
@@ -71,6 +74,7 @@ fn generate_struct(
 
     quote! {
         #variable_derives
+        #[serde(crate = #serde_path)]
         pub struct #struct_name{
             #(#fields,)*
         }

graphql_client_codegen/src/codegen/selection.rs

@@ -16,7 +16,7 @@ use crate::{
 };
 use heck::*;
 use proc_macro2::{Ident, Span, TokenStream};
-use quote::quote;
+use quote::{quote, ToTokens};
 use std::borrow::Cow;
 
 pub(crate) fn render_response_data_fields<'a>(
@@ -433,7 +433,7 @@ impl<'a> ExpandedField<'a> {
                 (Some(msg), DeprecationStrategy::Warn) => {
                     let optional_msg = msg.map(|msg| quote!((note = #msg)));
 
-                    Some(quote!(#[deprecated#optional_msg]))
+                    Some(quote!(#[deprecated #optional_msg]))
                 }
                 (Some(_), DeprecationStrategy::Deny) => return None,
             };
@@ -532,6 +532,9 @@ impl<'a> ExpandedSelection<'a> {
     }
 
     pub fn render(&self, response_derives: &impl quote::ToTokens) -> TokenStream {
+        let serde = self.options.serde_path();
+        let serde_path = serde.to_token_stream().to_string();
+
         let mut items = Vec::with_capacity(self.types.len());
 
         for (type_id, ty) in self.types() {
@@ -600,6 +603,7 @@ impl<'a> ExpandedSelection<'a> {
 
             let tokens = quote! {
                 #response_derives
+                #[serde(crate = #serde_path)]
                 pub struct #struct_name {
                     #(#fields,)*
                     #on_field

graphql_client_codegen/src/codegen_options.rs

@@ -47,6 +47,8 @@ pub struct GraphQLClientCodegenOptions {
     fragments_other_variant: bool,
     /// Skip Serialization of None values.
     skip_serializing_none: bool,
+    /// Path to the serde crate.
+    serde_path: syn::Path,
 }
 
 impl GraphQLClientCodegenOptions {
@@ -68,6 +70,7 @@ impl GraphQLClientCodegenOptions {
             extern_enums: Default::default(),
             fragments_other_variant: Default::default(),
             skip_serializing_none: Default::default(),
+            serde_path: syn::parse_quote!(::serde),
         }
     }
 
@@ -227,4 +230,14 @@ impl GraphQLClientCodegenOptions {
     pub fn skip_serializing_none(&self) -> &bool {
         &self.skip_serializing_none
     }
+
+    /// Set the path to used to resolve serde traits.
+    pub fn set_serde_path(&mut self, path: syn::Path) {
+        self.serde_path = path;
+    }
+
+    /// Get a reference to the path used to resolve serde traits.
+    pub fn serde_path(&self) -> &syn::Path {
+        &self.serde_path
+    }
 }

graphql_query_derive/src/lib.rs

@@ -104,6 +104,7 @@ fn build_graphql_client_derive_options(
     options.set_struct_ident(input.ident.clone());
     options.set_module_visibility(input.vis.clone());
     options.set_operation_name(input.ident.to_string());
+    options.set_serde_path(syn::parse_quote!(graphql_client::_private::serde));
 
     Ok(options)
 }