NodeJS Examples: UpdateCommand with list manipulation.

Author: Mo Kamioner

examples/SDK/node.js/sdk_v3/data_plane/WorkingWithItems/update-item-list.js

@@ -0,0 +1,116 @@
+// This is an example of an UpdateCommand using the higher level DocumentClient
+// for Amazon DynamoDB. It manipulates an list attribute on an item.
+
+const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");
+const { DynamoDBDocumentClient, UpdateCommand, PutCommand, GetCommand } = require("@aws-sdk/lib-dynamodb");
+
+const client = new DynamoDBClient({ region: "us-west-2" });
+const docClient = DynamoDBDocumentClient.from(client);
+
+async function createItem() {
+  // We create the item first so we have a point of reference of the changes.
+  const params = {
+    TableName: "RetailDatabase",
+    Item: {
+      pk: "jim.bob@somewhere.com",
+      sk: "metadata",
+      name: "Jim Bob",
+      favoriteColors: ['red', 'green', 'blue'],
+    },
+  };
+  await docClient.send(new PutCommand(params));
+}
+
+async function getFavoriteColors() {
+  const params = {
+    TableName: "RetailDatabase",
+    Key: {
+      pk: "jim.bob@somewhere.com",
+      sk: "metadata",
+    },
+    AttributesToGet: ['favoriteColors'], // No reason to get anything else
+  };
+  const response = await docClient.send(new GetCommand(params));
+  return response.Item.favoriteColors.join(', ');
+}
+
+async function addYellow() {
+  const params = {
+    TableName: "RetailDatabase",
+    Key: {
+      pk: "jim.bob@somewhere.com",
+      sk: "metadata",
+    },
+    UpdateExpression: "SET #fc = list_append(#fc, :colors)",
+    ExpressionAttributeNames: {
+      "#fc": "favoriteColors",
+    },
+    ExpressionAttributeValues: {
+      ":colors": ["yellow"],
+    },
+    ReturnValues: "ALL_NEW",
+  };
+
+  const response = await docClient.send(new UpdateCommand(params));
+  return response.Attributes.favoriteColors.join(', ');
+}
+
+async function removeGreen() {
+  const params = {
+    TableName: "RetailDatabase",
+    Key: {
+      pk: "jim.bob@somewhere.com",
+      sk: "metadata",
+    },
+    UpdateExpression: "REMOVE #fc[1]",
+    ExpressionAttributeNames: {
+      "#fc": "favoriteColors",
+    },
+    ReturnValues: "ALL_NEW",
+  };
+
+  const response = await docClient.send(new UpdateCommand(params));
+  return response.Attributes.favoriteColors.join(', ');
+}
+
+async function swapRedAndBlue() {
+  const params = {
+    TableName: "RetailDatabase",
+    Key: {
+      pk: "jim.bob@somewhere.com",
+      sk: "metadata",
+    },
+    UpdateExpression: "SET #fc[0] = #fc[1], #fc[1] = #fc[0]",
+    ExpressionAttributeNames: {
+      "#fc": "favoriteColors",
+    },
+    ReturnValues: "ALL_NEW",
+  };
+
+  const response = await docClient.send(new UpdateCommand(params));
+  return response.Attributes.favoriteColors.join(', ');
+}
+
+async function manipulateList() {
+  // We are creating the item for a fresh start
+  await createItem();
+
+  let favoriteColors = await getFavoriteColors();
+  console.log(`These are Jim's favorite colors: ${favoriteColors}`);
+
+  console.log("Yellow is one of Jim's favorite colors as well");
+  favoriteColors = await addYellow();
+  console.log(`Jim's new favorite colors: ${favoriteColors}`);
+
+  console.log("Green is not one of Jim's favorite colors anymore");
+  favoriteColors = await removeGreen();
+  console.log(`Jim's new favorite colors: ${favoriteColors}`);
+
+  console.log("Jim had a change of heart and he now likes blue more than red")
+  favoriteColors = await swapRedAndBlue();
+  console.log(`Jim's new favorite colors: ${favoriteColors}`);
+}
+
+manipulateList()
+  .then(() => console.log("Script completed"))
+  .catch((error) => console.error(error));