Update simple example for Node.js < v7.6

Author: gpahal

examples/simple/README.md

@@ -45,11 +45,18 @@ npm install
 ```
 
 ## Run the sample code
+For Node.js >= v7.6, run:
 
 ```sh
 node index.js
 ```
 
+For Node.js < v7.6 or if you don't want to use the async/await syntax, run:
+
+```sh
+node index-pre-v7.6.js
+```
+
 Your output should look something like this:
 
 ```
@@ -59,4 +66,4 @@ Alice
 DONE!
 ```
 
-You can explore the source code in the `index.js` file.
+You can explore the source code in the `index.js` and `index-pre-v7.6.js` files.

examples/simple/index-pre-v7.6.js

@@ -0,0 +1,100 @@
+const grpc = require("grpc");
+const dgraph = require("dgraph-js");
+
+function newClient() {
+    const clientStub = new dgraph.DgraphClientStub("localhost:9080", grpc.credentials.createInsecure());
+    return new dgraph.DgraphClient(clientStub);
+}
+
+// Drop All - discard all data and start from a clean slate.
+function dropAll(dgraphClient) {
+    const op = new dgraph.Operation();
+    op.setDropAll(true);
+    return dgraphClient.alter(op);
+}
+
+// Set schema.
+function setSchema(dgraphClient) {
+    const schema = "name: string @index(exact) .";
+    const op = new dgraph.Operation();
+    op.setSchema(schema);
+    return dgraphClient.alter(op);
+}
+
+// Create a node for a person with name Alice.
+function createAlice(dgraphClient) {
+    // Create a new transaction.
+    const txn = dgraphClient.newTxn();
+
+    // Create data.
+    const p = { name: "Alice" };
+
+    // Serialize it.
+    const json = JSON.stringify(p);
+
+    const serialized = new Uint8Array(new Buffer(json));
+    // OR if you want to use base64
+    // const serialized = new Buffer(json).toString("base64");
+
+    let err;
+
+    // Run mutation.
+    const mu = new dgraph.Mutation();
+    mu.setSetJson(serialized);
+    return txn.mutate(mu).then(() => {
+        // Commit transaction.
+        return txn.commit();
+    }).catch((e) => {
+        err = e;
+    }).then(() => {
+        return txn.discard();
+    }).then(() => {
+        if (err != null) {
+            throw err;
+        }
+    });
+}
+
+// Query for a person with name Alice.
+function queryAlice(dgraphClient) {
+    // Run query.
+    const query = `query all($a: string) {
+        all(func: eq(name, $a))
+        {
+            name
+        }
+    }`;
+    const vars = { $a: "Alice" };
+
+    return dgraphClient.newTxn().queryWithVars(query, vars).then((res) => {
+        // Deserialize result.
+        const jsonStr = new Buffer(res.getJson_asU8()).toString();
+        // OR if you want to use base64
+        // const jsonStr = new Buffer(res.getJson_asB64(), "base64").toString();
+
+        const ppl = JSON.parse(jsonStr);
+
+        // Print results.
+        console.log(`people found: ${ppl.all.length}`);
+        for (let i = 0; i < ppl.all.length; i += 1) {
+            console.log(ppl.all[i].name);
+        }
+    });
+}
+
+function main() {
+    const dgraphClient = newClient();
+    return dropAll(dgraphClient).then(() => {
+        return setSchema(dgraphClient);
+    }).then(() => {
+        return createAlice(dgraphClient);
+    }).then(() => {
+        return queryAlice(dgraphClient);
+    });
+}
+
+main().then(() => {
+    console.log("\nDONE!");
+}).catch((e) => {
+    console.log("ERROR: ", e);
+});