Update application.js

app/assets/javascripts/graphiql/rails/application.js

@@ -2,3 +2,31 @@
 //= require ./react-dom-15.5.4
 //= require ./fetch-0.10.1
 //= require ./graphiql-0.10.2
+
+    var parameters = {};
+
+    // Defines a GraphQL fetcher using the fetch API.
+    var graphQLEndpoint = "/graphql";
+    function graphQLFetcher(graphQLParams) {
+      return fetch(graphQLEndpoint, {
+        method: 'post',
+        headers: {
+           "Content-Type": "application/json",
+           "X-CSRF-Token": document.querySelector("meta[name=csrf-token]").getAttribute('content')
+        },
+
+        body: JSON.stringify(graphQLParams),
+        credentials: 'include',
+      }).then(function (response) {
+        return response.json()
+      });
+    }
+    var defaultQuery = undefined
+    // Render <GraphiQL /> into the body.
+    ReactDOM.render(
+      React.createElement(GraphiQL, {
+        fetcher: graphQLFetcher,
+        defaultQuery: defaultQuery
+      }),
+      document.getElementById("graphiql-container")
+    );