Add JSON Mutation Support (#15)

* Add JSON Mutation Support

* JSON stringify mutation

Co-authored-by: Abhimanyu Singh Gaur <12651351+abhimanyusinghgaur@users.noreply.github.com>

* Update src/dgraph.ts

Co-authored-by: Abhimanyu Singh Gaur <12651351+abhimanyusinghgaur@users.noreply.github.com>

* check for string instead of object

Co-authored-by: Abhimanyu Singh Gaur <12651351+abhimanyusinghgaur@users.noreply.github.com>

Author: jdgamble555

src/dgraph.ts

@@ -32,14 +32,14 @@ async function dqlQuery(query: string, variables: Record<string, any> = {}): Pro
   return response.json();
 }
 
-async function dqlMutate(mutate: string): Promise<GraphQLResponse> {
+async function dqlMutate(mutate: string | Object): Promise<GraphQLResponse> {
   const response = await fetch(`${process.env.DGRAPH_URL}/mutate?commitNow=true`, {
     method: "POST",
     headers: {
-      "Content-Type": "application/rdf",
+      "Content-Type": typeof mutate === 'string' ? "application/rdf" : "application/json",
       "X-Auth-Token": process.env.DGRAPH_TOKEN || ""
     },
-    body: mutate
+    body: typeof mutate === 'string' ? mutate : JSON.stringify(mutate)
   })
   if (response.status !== 200) {
     throw new Error("Failed to execute DQL Mutate")