Limit method in flask, python using SQLAlchemy

Limit method in flask, python using SQLAlchemy

 

In SQLAlchemy, you can use the limit() method to limit the number of rows returned by a query. To select the top N records, you can combine limit() with order_by() to sort the records and then retrieve the first N records.

Here's an example code to select the top N records from a table in a Flask web application using SQLAlchemy:

from flask import Flask from flask_sqlalchemy import SQLAlchemy app = Flask(__name__) app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql://user:password@localhost/mydatabase' db = SQLAlchemy(app) class Customer(db.Model): __tablename__ = 'customers' id = db.Column(db.Integer, primary_key=True) name = db.Column(db.String(100), nullable=False) @app.route('/top-customers/<int:n>') def top_customers(n): top_customers = db.session.query(Customer)\ .order_by(Customer.id.desc())\ .limit(n)\ .all() return render_template('top_customers.html', top_customers=top_customers)

In this example, we defined a model for the Customer table and a route to retrieve the top N customers from the database. We use the order_by() method to sort the customers by ID in descending order and the limit() method to limit the number of records returned by the query. The all() method is used to execute the query and retrieve all the records.

We can then render the top_customers in a template to display the result.

Here's an example template code:

{% for customer in top_customers %} <p>Customer Name: {{ customer.name }}</p> {% endfor %}

In this template code, we loop through the top_customers list and display the customer name for each record.

Happy Learning!! Happy Coding!!