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How to build Expense tracking with Lovable?

Learn how to build an expense tracker with Lovable using our step-by-step guide. Streamline budgeting, track spending, and boost your financial insights!

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How to build Expense tracking with Lovable?

 
Project Setup and File Organization
 

  • Create a new Lovable project by logging into your Lovable account and starting a new project.
  • Inside your project, you will create three new files: index.html, style.css, and expense.js.
  • Lovable does not use a terminal; therefore, all dependencies are added directly in the code. For this example, we use vanilla HTML, CSS, and JavaScript.

 
Creating the HTML Structure
 

  • In your project file explorer, create a file named index.html.
  • Insert the following code snippet into index.html; this creates the user interface with a form to add expenses and a list to display them.
  • Place the code exactly in the file so that it is the main content rendered by Lovable.

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Expense Tracker</title>
    <link rel="stylesheet" href="style.css">
  </head>
  <body>
    <h1>Expense Tracker</h1>
    <form id="expense-form">
      <input type="text" id="description" placeholder="Expense Description">
      <input type="number" id="amount" placeholder="Amount">
      <button type="submit">Add Expense</button>
    </form>
    <ul id="expense-list"></ul>
    <script src="expense.js"></script>
  </body>
</html>

 
Adding CSS Styling
 

  • Create a file named style.css in your Lovable project.
  • Insert the following CSS code to style the application interface. This provides basic styling for the form and expense list.

body {
  font-family: Arial, sans-serif;
  margin: 20px;
  background-color: #f4f4f4;
}

h1 {
  text-align: center;
}

form {
  max-width: 400px;
  margin: 0 auto 20px;
  display: flex;
  gap: 10px;
}

input[type="text"],
input[type="number"] {
  flex: 1;
  padding: 8px;
  border: 1px solid #ccc;
  border-radius: 4px;
}

button {
  padding: 8px 12px;
  border: none;
  border-radius: 4px;
  background-color: #5cb85c;
  color: #fff;
  cursor: pointer;
}

ul#expense-list {
  max-width: 400px;
  margin: 0 auto;
  list-style-type: none;
  padding: 0;
}

ul#expense-list li {
  background-color: #fff;
  margin-bottom: 8px;
  padding: 10px;
  border-radius: 4px;
  border: 1px solid #ddd;
}

 
Implementing the Expense Tracking Logic
 

  • Create a file named expense.js in your Lovable project.
  • Insert the following JavaScript code into expense.js. This script handles form submissions, stores expense entries in localStorage, and displays them on page load.
  • Ensure this file is saved exactly as expense.js and referenced in your index.html as shown earlier.

document.getElementById('expense-form').addEventListener('submit', function(e) {
  e.preventDefault();
  var description = document.getElementById('description').value;
  var amount = document.getElementById('amount').value;
  
  if(description && amount) {
    // Create a new expense list item
    var expenseItem = document.createElement('li');
    expenseItem.textContent = description + " - $" + amount;
    document.getElementById('expense-list').appendChild(expenseItem);
    
    // Save to localStorage
    var expenses = JSON.parse(localStorage.getItem('expenses')) || [];
    expenses.push({description: description, amount: amount});
    localStorage.setItem('expenses', JSON.stringify(expenses));
    
    // Clear the form inputs
    document.getElementById('description').value = '';
    document.getElementById('amount').value = '';
  }
});

// Load saved expenses when the page loads
window.addEventListener('load', function() {
  var expenses = JSON.parse(localStorage.getItem('expenses')) || [];
  var expenseList = document.getElementById('expense-list');
  expenses.forEach(function(exp) {
    var expenseItem = document.createElement('li');
    expenseItem.textContent = exp.description + " - $" + exp.amount;
    expenseList.appendChild(expenseItem);
  });
});

 
Finalizing and Testing Your Expense Tracker
 

  • Review all the files (index.html, style.css, and expense.js) to ensure the code is correctly inserted.
  • Use Lovable’s built-in preview feature to load index.html and interact with your expense tracker by adding expense entries.
  • Changes to your files are automatically applied when you refresh the preview.

 
Adding Dependency Comments (If Needed)
 

  • If you need to include third-party libraries (for example, for advanced date formatting or charts), you can add them by inserting a script tag in the <head> section of index.html.
  • No terminal installation is required. Simply add the external library URL like this:

<script src="https://cdn.example.com/library.js"></script>

 
Review
 

  • You now have an expense tracker built on Lovable that uses HTML, CSS, and JavaScript.
  • The logic to store expenses in the browser’s localStorage ensures that added records persist across page reloads.
  • You can later extend this project with additional features such as expense editing, deletion, or charts by following similar patterns.

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How to Build an Expense Tracking API with Lovable Using Express and Mongoose


const express = require('express');
const mongoose = require('mongoose');
const app = express();

app.use(express.json());

mongoose.connect('mongodb://localhost:27017/lovable-expenses', { useNewUrlParser: true, useUnifiedTopology: true })
  .then(() => console.log('MongoDB connected'))
  .catch(err => console.error(err));

const expenseSchema = new mongoose.Schema({
  userId: { type: mongoose.Schema.Types.ObjectId, required: true, ref: 'User' },
  amount: { type: Number, required: true },
  category: { type: String, required: true },
  date: { type: Date, default: Date.now },
  description: String,
  paymentMethod: String
});

const Expense = mongoose.model('Expense', expenseSchema);

app.post('/api/expenses', async (req, res) => {
  try {
    const expense = new Expense(req.body);
    await expense.save();
    res.status(201).json(expense);
  } catch (error) {
    res.status(400).json({ error: error.message });
  }
});

app.get('/api/expenses', async (req, res) => {
  try {
    const { userId, category } = req.query;
    const query = {};
    if (userId) query.userId = userId;
    if (category) query.category = category;
    const expenses = await Expense.find(query).sort({ date: -1 });
    res.json(expenses);
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

app.get('/api/expenses/summary', async (req, res) => {
  try {
    const { userId, startDate, endDate } = req.query;
    const match = { userId: mongoose.Types.ObjectId(userId) };
    if (startDate || endDate) {
      match.date = {};
      if (startDate) match.date.$gte = new Date(startDate);
      if (endDate) match.date.$lte = new Date(endDate);
    }
    const summary = await Expense.aggregate([
      { $match: match },
      { $group: { \_id: "$category", totalAmount: { $sum: "$amount" } } }
    ]);
    res.json(summary);
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => console.log(`Server running on port ${PORT}`));

How to add currency conversion to your expense tracker with Lovable


const express = require('express');
const axios = require('axios');
const router = express.Router();

router.get('/api/expenses/convert', async (req, res) => {
  try {
    const { amount, fromCurrency, toCurrency } = req.query;
    if (!amount || !fromCurrency || !toCurrency) {
      return res.status(400).json({ error: 'Missing required query parameters: amount, fromCurrency, toCurrency' });
    }

    const apiKey = process.env.CURRENCY_API_KEY;
    const apiUrl = `https://api.exchangerate-api.com/v4/latest/${fromCurrency}`;
    const response = await axios.get(apiUrl);
    
    if (!response.data || !response.data.rates) {
      return res.status(500).json({ error: 'Failed to retrieve conversion rates.' });
    }
    
    const conversionRate = response.data.rates[toCurrency];
    if (!conversionRate) {
      return res.status(400).json({ error: 'Target currency not supported.' });
    }
    
    const convertedAmount = parseFloat(amount) \* conversionRate;
    
    res.json({
      originalAmount: parseFloat(amount),
      fromCurrency,
      toCurrency,
      conversionRate,
      convertedAmount
    });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

module.exports = router;

How to update expenses and send automated budget alerts with Lovable


const express = require('express');
const mongoose = require('mongoose');
const nodemailer = require('nodemailer');
const router = express.Router();

const expenseSchema = new mongoose.Schema({
  userId: { type: mongoose.Schema.Types.ObjectId, ref: 'User', required: true },
  amount: { type: Number, required: true },
  category: { type: String, required: true },
  date: { type: Date, default: Date.now },
  description: String
});
const Expense = mongoose.model('Expense', expenseSchema);

const userSchema = new mongoose.Schema({
  email: { type: String, required: true },
  monthlyBudget: { type: Number, required: true }
});
const User = mongoose.model('User', userSchema);

const transporter = nodemailer.createTransport({
  service: 'gmail',
  auth: {
    user: process.env.EMAIL\_USER,
    pass: process.env.EMAIL\_PASS
  }
});

router.put('/api/expenses/:id', async (req, res) => {
  try {
    const expenseId = req.params.id;
    const updatedData = req.body;
    const expense = await Expense.findByIdAndUpdate(expenseId, updatedData, { new: true });
    if (!expense) return res.status(404).json({ error: 'Expense not found' });
    
    const startOfMonth = new Date(expense.date.getFullYear(), expense.date.getMonth(), 1);
    const endOfMonth = new Date(expense.date.getFullYear(), expense.date.getMonth() + 1, 0);
    
    const monthlyExpenses = await Expense.aggregate([
      { $match: { userId: expense.userId, date: { $gte: startOfMonth, $lte: endOfMonth } } },
      { $group: { \_id: null, total: { $sum: "$amount" } } }
    ]);
    
    const user = await User.findById(expense.userId);
    if (user && monthlyExpenses.length > 0 && monthlyExpenses[0].total > user.monthlyBudget) {
      await transporter.sendMail({
        from: process.env.EMAIL\_USER,
        to: user.email,
        subject: 'Alert: Monthly Budget Exceeded',
        text: `You have exceeded your monthly budget of ${user.monthlyBudget}. Your current total is ${monthlyExpenses[0].total}.`
      });
    }
    res.json(expense);
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

module.exports = router;

Want to explore opportunities to work with us?

Connect with our team to unlock the full potential of no-code solutions with a no-commitment consultation!

Book a Free Consultation
Matt Graham, CEO of Rapid Developers

Book a call with an Expert

Starting a new venture? Need to upgrade your web app? RapidDev builds application with your growth in mind.

Book a free No-Code consultation

Best Practices for Building a Expense tracking with AI Code Generators

 
Understanding the Project Scope and Objectives
 

  • Begin by defining what the expense tracking app will do. For example, it should record, categorize, and analyze your expenses.
  • List out features such as receipt scanning, automatic categorization using AI, data visualization, and report generation.
  • Decide on the target user who may range from individuals managing personal budgets to small businesses keeping track of expenditures.

 
Researching AI Code Generators
 

  • Identify AI code generator tools that can assist in building parts of the expense tracker. Tools like GitHub Copilot, Tabnine, or custom GPT-4 based generators are popular.
  • Gather information on how these tools integrate with your development environment and programming languages in use.
  • Review best practices such as code review, version control, and unit testing when using AI-generated code.

 
Setting Up Your Development Environment
 

  • Install all required software. For a web-based expense tracker, you might need tools like Node.js for the back end or Python with key frameworks.
  • Set up a version control system like Git to manage your source code efficiently.
  • Configure your development environment to work seamlessly with your chosen AI code generator. This often involves installing plug-ins or extensions in your IDE.

 
Designing the Application Architecture
 

  • Decide if your application will be a web app, mobile app, or both. For a web app, define the client-server interaction.
  • Sketch the overall architecture including front-end, back-end, and database design. For example:
    • Front-end: User interface built with HTML, CSS, and JavaScript frameworks like React.
    • Back-end: API server to manage data requests, possibly using Python/Flask or Node.js/Express.
    • Database: SQL or NoSQL database to store expenses, user data, and receipts.

 
Integrating AI for Automatic Code Generation
 

  • Leverage AI code generators for recurring code patterns. For instance, generating CRUD operations or API endpoints.
  • Follow iterative steps:
    • Generate a basic function using the AI tool.
    • Examine the generated code carefully for correctness and best coding practices.
    • Integrate the code into your project and test it thoroughly.
  • Example: Generating a function to add a new expense. Review and modify AI-generated code as needed: 
    
def add_expense(expenses, new_entry):
    """
    Adds a new expense entry to the list.
    :param expenses: Current list of expenses.
    :param new\_entry: Dictionary with expense details.
    :return: Updated list of expenses.
    """
    expenses.append(new\_entry)
    return expenses

 
Building the User Interface
 

  • Create simple and intuitive layouts. Use design tools or frameworks such as Bootstrap to streamline the process.
  • Keep navigation clear with sections for adding expenses, viewing summaries, and generating reports.
  • Integrate AI-generated components like dynamic search or predictive input fields to improve usability.

 
Implementing Core Functionalities
 

  • Develop key features of your expense tracker such as expense entry forms, history displays, and analytical dashboards.
  • Use AI code generators to produce boilerplate code for database queries or web service connections, then refine manually.
  • Ensure proper error handling and validations in every form and function.

 
Testing and Quality Assurance
 

  • Always test the functionality provided by the AI-generated code as well as your manually written code.
  • Use testing frameworks like Jest for JavaScript or PyTest for Python to automate unit and integration tests.
  • Manually test the user interface to detect any logic issues or user experience concerns.

 
Security Best Practices
 

  • Implement proper authentication and authorization measures to secure user data.
  • Encrypt sensitive data both in transit and at rest. Avoid using AI-generated code blindly for security-critical functionalities.
  • Review generated code for vulnerabilities such as SQL injections or weak API endpoints, and fix them if found.

 
Documentation and Version Control
 

  • Maintain detailed documentation of all code changes and how to integrate AI-generated sections with manual implementations.
  • Use version control commit messages to keep track of which parts were AI-generated and what modifications were made afterward.
  • Include in-code comments and external documentation files explaining how each component works.

 
Deployment and Maintenance
 

  • Choose deployment platforms based on your technology stack, such as Heroku, AWS, or DigitalOcean.
  • Set up continuous integration and continuous deployment (CI/CD) pipelines to streamline future updates.
  • Monitor usage, performance, and security issues regularly after deployment. Use logging and analytics tools to track issues and user behaviors.

 
Iterating and Learning
 

  • Collect user feedback to identify areas for improvement and new features.
  • Continuously update both the AI components and manual code segments to meet user requirements.
  • Keep updated with advances in AI code generation to further optimize your development process.

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