Add support for file uploads in Relay Environment

Add support for file uploads in RelayEnvironment by implementing
multipart form[1] handling via FormData when uploadables are
present. Maintain backward compatibility for standard GraphQL queries.

[1] https://github.com/jaydenseric/graphql-multipart-request-spec

Signed-off-by: gearnode <bryan@frimin.fr>

apps/console/src/RelayEnvironment.ts

@@ -7,21 +7,60 @@ import {
 } from "relay-runtime";
 import { buildEndpoint } from "./utils";
 
-const fetchRelay: FetchFunction = async (request, variables) => {
-  const response = await fetch(buildEndpoint("/console/v1/query"), {
-    method: "POST",
-    credentials: "include",
-    headers: {
-      Accept:
-        "application/graphql-response+json; charset=utf-8, application/json; charset=utf-8",
-      "Content-Type": "application/json",
-    },
-    body: JSON.stringify({
+const fetchRelay: FetchFunction = async (request, variables, _, uploadables) => {
+  const requestInit: RequestInit = {
+    method: 'POST',
+    credentials: 'include',
+    headers: {},
+  };
+
+
+  if (uploadables) {
+    const formData = new FormData();
+    formData.append(
+      'operations',
+      JSON.stringify({
+        operationName: request.name,
+        query: request.text,
+        variables: variables,
+      })
+    );
+
+
+    const uploadableMap: {
+      [key: string]: string[];
+    } = {};
+
+    Object.keys(uploadables).forEach((key, index) => {
+      if (Object.prototype.hasOwnProperty.call(uploadables, key)) {
+        uploadableMap[index] = [`variables.${key}`];
+      }
+    });
+
+    formData.append('map', JSON.stringify(uploadableMap));
+
+    Object.keys(uploadables).forEach((key, index) => {
+      if (Object.prototype.hasOwnProperty.call(uploadables, key)) {
+        formData.append(index.toString(), uploadables[key]);
+      }
+    });
+
+    requestInit.body = formData;
+
+  } else {
+    requestInit.headers = {
+      "Accept": "application/graphql-response+json; charset=utf-8, application/json; charset=utf-8",
+      "Content-Type": "application/json"
+    }
+
+    requestInit.body = JSON.stringify({
       operationName: request.name,
       query: request.text,
       variables,
-    }),
-  });
+    });
+  }
+
+  const response = await fetch(buildEndpoint("/console/v1/query"), requestInit);
 
   const json = await response.json();