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Automate Workflows with AWS Step Functions

Add Shaping Step to State Machine

Understand how to add a shaping step in your AWS Step Functions state machine using a Lambda function. Explore updating task states, setting transitions between states, and configuring automatic retries to ensure resilient workflow execution.

We'll cover the following...

Shaping step in our workflow

Let's define the shaping step in our state machine. It will be a Task state that uses the Lambda function we just defined.

import { DynamoDB } from "aws-sdk";
import { APIGatewayProxyEvent, APIGatewayProxyResult } from "aws-lambda";

const dynamoDB = new DynamoDB.DocumentClient();
const tableName = process.env.INVENTORY_TABLE;

interface Ingredient {
  ingredient: string;
  quantity: number;
}

export const handler = async (
  event: APIGatewayProxyEvent
): Promise<APIGatewayProxyResult> => {
  const requiredIngredients: Ingredient[] = JSON.parse(
    event.body
  ).requiredIngredients;

  const insufficientIngredients = await Promise.all(
    requiredIngredients.map(async (ingredient) => {
      const result = await dynamoDB
        .get({
          TableName: tableName,
          Key: { ingredient: ingredient.ingredient },
        })
        .promise();

      if (!result.Item || result.Item.quantity < ingredient.quantity) {
        return {
          ingredient: ingredient.ingredient,
          quantity:
            ingredient.quantity - (result.Item ? result.Item.quantity : 0),
        };
      }

      await dynamoDB
        .update({
          TableName: tableName,
          Key: { ingredient: ingredient.ingredient },
          UpdateExpression: "SET quantity = :newQuantity",
          ExpressionAttributeValues: {
            ":newQuantity": result.Item.quantity - ingredient.quantity,
          },
        })
        .promise();

      return null;
    })
  );

  const filteredInsufficientIngredients = insufficientIngredients.filter(
    (item) => item !== null
  );

  if (filteredInsufficientIngredients.length === 0) {
    return {
      statusCode: 200,
      body: {
        status: "success",
        ingredients: requiredIngredients,
      },
    };
  } else {
    return {
      statusCode: 400,
      body: {
        status: "insufficient",
        insufficientIngredients: filteredInsufficientIngredients,
      },
    };
  }
};
Project

First, within the ...