使用 AWS Lambda 和 DynamoDB 建立 REST API 應用程式

AWS
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建立資料表

首先，在 DynamoDB 建立一個資料表。

  • Table name: http-crud-tutorial-items
  • Partition key: id
  • 選擇 On-demand 模式

建立函式

在 AWS Lambda 建立一個函式。

  • Function name: http-crud-tutorial-function
  • Runtime: Node.js
  • Execution role name: http-crud-tutorial-role
  • Policy templates: Simple microservice permissions

建立範例函式：

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import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import {
  DynamoDBDocumentClient,
  ScanCommand,
  PutCommand,
  GetCommand,
  DeleteCommand,
} from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});

const dynamo = DynamoDBDocumentClient.from(client);

const tableName = "http-crud-tutorial-items";

export const handler = async (event, context) => {
  let body;
  let statusCode = 200;
  const headers = {
    "Content-Type": "application/json",
  };

  try {
    switch (event.routeKey) {
      case "DELETE /items/{id}":
        await dynamo.send(
          new DeleteCommand({
            TableName: tableName,
            Key: {
              id: event.pathParameters.id,
            },
          })
        );
        body = `Deleted item ${event.pathParameters.id}`;
        break;
      case "GET /items/{id}":
        body = await dynamo.send(
          new GetCommand({
            TableName: tableName,
            Key: {
              id: event.pathParameters.id,
            },
          })
        );
        body = body.Item;
        break;
      case "GET /items":
        body = await dynamo.send(
          new ScanCommand({ TableName: tableName })
        );
        body = body.Items;
        break;
      case "PUT /items":
        let requestJSON = JSON.parse(event.body);
        await dynamo.send(
          new PutCommand({
            TableName: tableName,
            Item: {
              id: requestJSON.id,
              price: requestJSON.price,
              name: requestJSON.name,
            },
          })
        );
        body = `Put item ${requestJSON.id}`;
        break;
      default:
        throw new Error(`Unsupported route: "${event.routeKey}"`);
    }
  } catch (err) {
    statusCode = 400;
    body = err.message;
  } finally {
    body = JSON.stringify(body);
  }

  return {
    statusCode,
    body,
    headers,
  };
};

點選 Deploy 按鈕。

建立 API

到 API Gateway 建立一個 REST API。

  • API name: http-crud-tutorial-api

建立 routes 如下：

  • GET /items/{id}
  • GET /items
  • PUT /items
  • DELETE /items/{id}

為每個路由建立 integration 如下：

  • 選擇路由
  • Integration type: Lambda function
  • Choose an existing integration: http-crud-tutorial-function

測試

新增物件

使用 curl 進行呼叫。

1
curl -X "PUT" -H "Content-Type: application/json" -d "{\"id\": \"123\", \"price\": 12345, \"name\": \"myitem\"}" https://xxx.execute-api.ap-northeast-1.amazonaws.com/items

回應如下：

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"Put item 123"

取得物件列表

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curl https://xxx.execute-api.ap-northeast-1.amazonaws.com/items

回應如下：

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[{"price":12345,"id":"123","name":"myitem"}]

取得指定物件

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curl https://xxx.execute-api.ap-northeast-1.amazonaws.com/items/123

回應如下：

1
{"price":12345,"id":"123","name":"myitem"}

刪除物件

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curl -X "DELETE" https://xxx.execute-api.ap-northeast-1.amazonaws.com/items/123

回應如下：

1
"Deleted item 123"

參考資料