AI Recipe Generation

Introduction: AI-Powered Recipe Generation

Welcome to this lesson on generating new recipes with AI! So far, you have learned how to interact with large language models (LLMs), structure prompts, and manage LLM calls in your TypeScript application using Express . Now, you will see how these skills come together to create a feature that generates unique cooking recipes based on a list of ingredients provided by the user. Imagine you have a few ingredients in your fridge and want to know what you can cook. With AI-powered recipe generation, your app can suggest creative, step-by-step recipes instantly. This not only makes your app more helpful but also demonstrates the power of combining AI with modern web development in TypeScript. In this lesson, you will learn how to connect your Express backend to the AI, send ingredient lists, and return structured recipes to your users. By the end, you will understand the full flow of generating a recipe with AI and preparing it for use in your application.

Quick Recall: Prompts and LLM Manager

Before we dive in, let’s briefly recall two important concepts from previous lessons: Prompt Templates: You learned how to use template files to create prompts for the AI. These templates can include placeholders (like {{ingredients}}) that are filled in with real values before being sent to the AI. LLM Manager: The LLM Manager is a helper that handles all communication with the language model. It loads the right prompts, fills in variables, sends the request, and returns the AI’s response. These tools are the foundation for generating recipes with AI. In this lesson, you will see how they are used together in a real Express route.

How Recipe Generation Works in Express

Let’s walk through how your Express app generates a recipe using AI, step by step.

1. The API Route

Your app provides a special route for generating recipes: TypeScript import { Router } from "express"; import { z } from "zod"; import { generateResponse } from "../services/llm"; import { parseAiRecipe } from "../utils/parser"; export const recipes = Router(); recipes.post("/generate", async (req, res) => {const body = z.object({ ingredients: z.array(z.string()).min(1) }).safeParse(req.body); if (!body.success) return res.status(400).json({ error: "No ingredients provided" }); const ingredientStr = body.data.ingredients.join(", "); // ... (rest of the code)}); import { Router } from "express"; import { z } from "zod"; import { generateResponse } from "../services/llm"; import { parseAiRecipe } from "../utils/parser"; export const recipes = Router(); recipes.post("/generate", async (req, res) => {const body = z.object({ ingredients: z.array(z.string()).min(1) }).safeParse(req.body); if (!body.success) return res.status(400).json({ error: "No ingredients provided" }); const ingredientStr = body.data.ingredients.join(", "); // ... (rest of the code)}); This route listens for POST requests at /generate . It expects a JSON body with an ingredients array. If no ingredients are provided, it returns an error. Example request: JSON {"ingredients": ["chicken", "rice", "broccoli"]} {"ingredients": ["chicken", "rice", "broccoli"]}

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TypeScript

import { Router } from "express";
import { z } from "zod";
import { generateResponse } from "../services/llm";
import { parseAiRecipe } from "../utils/parser";

export const recipes = Router();

recipes.post("/generate", async (req, res) => {
  const body = z.object({ ingredients: z.array(z.string()).min(1) }).safeParse(req.body);
  if (!body.success) return res.status(400).json({ error: "No ingredients provided" });
  const ingredientStr = body.data.ingredients.join(", ");

  // ... (rest of the code)
});

JSON

{
  "ingredients": ["chicken", "rice", "broccoli"]
}

TypeScript

const ai = await generateResponse(
  "recipe_gen_system",
  "recipe_gen_user",
  { ingredients: ingredientStr }
);

const ai = await generateResponse(
  "recipe_gen_system",
  "recipe_gen_user",
  { ingredients: ingredientStr }
);

text

Name: Chicken and Broccoli Rice Bowl
Ingredients:
- chicken
- rice
- broccoli
Steps:
1. Cook the rice.
2. Sauté the chicken.
3. Add broccoli and mix everything together.

Name: Chicken and Broccoli Rice Bowl
Ingredients:
- chicken
- rice
- broccoli
Steps:
1. Cook the rice.
2. Sauté the chicken.
3. Add broccoli and mix everything together.

TypeScript

let name: string | null = null;
const parsedIngredients: string[] = [];
const steps: string[] = [];

const lines = response.trim().split('\n');
let section: string | null = null;

let name: string | null = null;
const parsedIngredients: string[] = [];
const steps: string[] = [];

const lines = response.trim().split('\n');
let section: string | null = null;

TypeScript

for (const line of lines) {
  if (line.toLowerCase().startsWith("name:")) {
    name = line.split(":").slice(1).join(":").trim();
    section = null;
  } else if (line.toLowerCase().startsWith("ingredients:")) {
    section = "ingredients";
  } else if (line.toLowerCase().startsWith("steps:")) {
    section = "steps";
  } else if (section === "ingredients" && line.trim().startsWith("-")) {
    parsedIngredients.push(line.trim().substring(1).trim());
  } else if (section === "steps" && /^\d/.test(line.trim())) {
    steps.push(line.trim());
  }
}

for (const line of lines) {
  if (line.toLowerCase().startsWith("name:")) {
    name = line.split(":").slice(1).join(":").trim();
    section = null;
  } else if (line.toLowerCase().startsWith("ingredients:")) {
    section = "ingredients";
  } else if (line.toLowerCase().startsWith("steps:")) {
    section = "steps";
  } else if (section === "ingredients" && line.trim().startsWith("-")) {
    parsedIngredients.push(line.trim().substring(1).trim());
  } else if (section === "steps" && /^\d/.test(line.trim())) {
    steps.push(line.trim());
  }
}

TypeScript

return res.json({
  name: name,
  ingredients: parsedIngredients,
  steps: steps
});

return res.json({
  name: name,
  ingredients: parsedIngredients,
  steps: steps
});

JSON

{
  "name": "Chicken and Broccoli Rice Bowl",
  "ingredients": ["chicken", "rice", "broccoli"],
  "steps": [
    "1. Cook the rice.",
    "2. Sauté the chicken.",
    "3. Add broccoli and mix everything together."
  ]
}

{
  "name": "Chicken and Broccoli Rice Bowl",
  "ingredients": ["chicken", "rice", "broccoli"],
  "steps": [
    "1. Cook the rice.",
    "2. Sauté the chicken.",
    "3. Add broccoli and mix everything together."
  ]
}

TypeScript

import { Router } from "express";
import { z } from "zod";
import { generateResponse } from "../services/llm";
import { parseAiRecipe } from "../utils/parser";

export const recipes = Router();

recipes.post("/generate", async (req, res) => {
  const body = z.object({ ingredients: z.array(z.string()).min(1) }).safeParse(req.body);
  if (!body.success) return res.status(400).json({ error: "No ingredients provided" });
  const ingredientStr = body.data.ingredients.join(", ");

  // Generate the AI response using prompt templates
  const ai = await generateResponse(
    "recipe_gen_system",
    "recipe_gen_user",
    { ingredients: ingredientStr }
  );
  if (!ai) return res.status(500).json({ error: "Failed to generate recipe" });

  // Parse the AI's response
  try {
    const parsed = parseAiRecipe(ai);
    return res.json(parsed);
  } catch {
    return res.status(500).json({ error: "Invalid recipe format from AI" });
  }
});

import { Router } from "express";
import { z } from "zod";
import { generateResponse } from "../services/llm";
import { parseAiRecipe } from "../utils/parser";

export const recipes = Router();

recipes.post("/generate", async (req, res) => {
  const body = z.object({ ingredients: z.array(z.string()).min(1) }).safeParse(req.body);
  if (!body.success) return res.status(400).json({ error: "No ingredients provided" });
  const ingredientStr = body.data.ingredients.join(", ");

  // Generate the AI response using prompt templates
  const ai = await generateResponse(
    "recipe_gen_system",
    "recipe_gen_user",
    { ingredients: ingredientStr }
  );
  if (!ai) return res.status(500).json({ error: "Failed to generate recipe" });

  // Parse the AI's response
  try {
    const parsed = parseAiRecipe(ai);
    return res.json(parsed);
  } catch {
    return res.status(500).json({ error: "Invalid recipe format from AI" });
  }
});

TypeScript

// src/utils/parser.ts
export function parseAiRecipe(text: string) {
  const lines = text.trim().split('\n');
  let name: string | null = null;
  const ingredients: string[] = [];
  const steps: string[] = [];
  let section: string | null = null;

  for (const line of lines) {
    if (line.toLowerCase().startsWith("name:")) {
      name = line.split(":").slice(1).join(":").trim();
      section = null;
    } else if (line.toLowerCase().startsWith("ingredients:")) {
      section = "ingredients";
    } else if (line.toLowerCase().startsWith("steps:")) {
      section = "steps";
    } else if (section === "ingredients" && line.trim().startsWith("-")) {
      ingredients.push(line.trim().substring(1).trim());
    } else if (section === "steps" && /^\d/.test(line.trim())) {
      steps.push(line.trim());
    }
  }
  
  return { name, ingredients, steps };
}

// src/utils/parser.ts
export function parseAiRecipe(text: string) {
  const lines = text.trim().split('\n');
  let name: string | null = null;
  const ingredients: string[] = [];
  const steps: string[] = [];
  let section: string | null = null;

  for (const line of lines) {
    if (line.toLowerCase().startsWith("name:")) {
      name = line.split(":").slice(1).join(":").trim();
      section = null;
    } else if (line.toLowerCase().startsWith("ingredients:")) {
      section = "ingredients";
    } else if (line.toLowerCase().startsWith("steps:")) {
      section = "steps";
    } else if (section === "ingredients" && line.trim().startsWith("-")) {
      ingredients.push(line.trim().substring(1).trim());
    } else if (section === "steps" && /^\d/.test(line.trim())) {
      steps.push(line.trim());
    }
  }
  
  return { name, ingredients, steps };
}

TypeScript

const ai = await generateResponse(
  "recipe_gen_system",
  "recipe_gen_user",
  { ingredients: ingredientStr }
);

text

Name: Chicken and Broccoli Rice Bowl
Ingredients:
- chicken
- rice
- broccoli
Steps:
1. Cook the rice.
2. Sauté the chicken.
3. Add broccoli and mix everything together.

TypeScript

let name: string | null = null;
const parsedIngredients: string[] = [];
const steps: string[] = [];

const lines = response.trim().split('\n');
let section: string | null = null;

TypeScript

for (const line of lines) {
  if (line.toLowerCase().startsWith("name:")) {
    name = line.split(":").slice(1).join(":").trim();
    section = null;
  } else if (line.toLowerCase().startsWith("ingredients:")) {
    section = "ingredients";
  } else if (line.toLowerCase().startsWith("steps:")) {
    section = "steps";
  } else if (section === "ingredients" && line.trim().startsWith("-")) {
    parsedIngredients.push(line.trim().substring(1).trim());
  } else if (section === "steps" && /^\d/.test(line.trim())) {
    steps.push(line.trim());
  }
}

TypeScript

return res.json({
  name: name,
  ingredients: parsedIngredients,
  steps: steps
});

JSON

{
  "name": "Chicken and Broccoli Rice Bowl",
  "ingredients": ["chicken", "rice", "broccoli"],
  "steps": [
    "1. Cook the rice.",
    "2. Sauté the chicken.",
    "3. Add broccoli and mix everything together."
  ]
}

TypeScript

import { Router } from "express";
import { z } from "zod";
import { generateResponse } from "../services/llm";
import { parseAiRecipe } from "../utils/parser";

export const recipes = Router();

recipes.post("/generate", async (req, res) => {
  const body = z.object({ ingredients: z.array(z.string()).min(1) }).safeParse(req.body);
  if (!body.success) return res.status(400).json({ error: "No ingredients provided" });
  const ingredientStr = body.data.ingredients.join(", ");

  // Generate the AI response using prompt templates
  const ai = await generateResponse(
    "recipe_gen_system",
    "recipe_gen_user",
    { ingredients: ingredientStr }
  );
  if (!ai) return res.status(500).json({ error: "Failed to generate recipe" });

  // Parse the AI's response
  try {
    const parsed = parseAiRecipe(ai);
    return res.json(parsed);
  } catch {
    return res.status(500).json({ error: "Invalid recipe format from AI" });
  }
});

TypeScript

// src/utils/parser.ts
export function parseAiRecipe(text: string) {
  const lines = text.trim().split('\n');
  let name: string | null = null;
  const ingredients: string[] = [];
  const steps: string[] = [];
  let section: string | null = null;

  for (const line of lines) {
    if (line.toLowerCase().startsWith("name:")) {
      name = line.split(":").slice(1).join(":").trim();
      section = null;
    } else if (line.toLowerCase().startsWith("ingredients:")) {
      section = "ingredients";
    } else if (line.toLowerCase().startsWith("steps:")) {
      section = "steps";
    } else if (section === "ingredients" && line.trim().startsWith("-")) {
      ingredients.push(line.trim().substring(1).trim());
    } else if (section === "steps" && /^\d/.test(line.trim())) {
      steps.push(line.trim());
    }
  }
  
  return { name, ingredients, steps };
}

Introduction: AI-Powered Recipe Generation

Quick Recall: Prompts and LLM Manager

How Recipe Generation Works in Express

1. The API Route

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2. Preparing the Prompts

3. Getting the AI’s Response

Parsing and Structuring the AI’s Recipe

1. Splitting the Response

2. Extracting Each Section Using String Methods

3. Returning the Structured Recipe

Putting It All Together: Full Implementation

Summary and Practice Preview