python 51 lines · 7 steps

Building a Flask seed command with Click

A custom Flask CLI command fills the database with fake users and products for local development.

Explained by highlit
Flask Intermediate cli database seeding orm test data click options
1import random
2 
3import click
4from faker import Faker
5 
6from app import app, db
7from app.models import Category, Product, User
8 
9fake = Faker()
10 
11 
12@app.cli.command("seed")
13@click.option("--users", default=20, help="Number of users to create.")
14@click.option("--products", default=100, help="Number of products to create.")
15@click.option("--flush/--no-flush", default=False, help="Wipe tables first.")
16def seed(users, products, flush):
17 """Populate the database with sample data."""
18 if flush:
19 click.echo("Flushing existing records...")
20 Product.query.delete()
21 Category.query.delete()
22 User.query.delete()
23 db.session.commit()
24 
25 categories = [
26 Category(name=name, slug=name.lower())
27 for name in ("Books", "Electronics", "Home", "Toys", "Garden")
28 ]
29 db.session.add_all(categories)
30 
31 with click.progressbar(range(users), label="Creating users") as bar:
32 for _ in bar:
33 user = User(email=fake.unique.email(), name=fake.name())
34 user.set_password("password")
35 db.session.add(user)
36 
37 with click.progressbar(range(products), label="Creating products") as bar:
38 for _ in bar:
39 db.session.add(
40 Product(
41 name=fake.catch_phrase(),
42 price=round(random.uniform(4.99, 499.99), 2),
43 stock=random.randint(0, 250),
44 category=random.choice(categories),
45 )
46 )
47 
48 db.session.commit()
49 click.secho(
50 f"Seeded {users} users and {products} products.", fg="green"
51 )
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1Registering a command under app.cli lets you script database tasks that run inside the app context.
  2. 2Batching inserts and committing once at the end keeps seeding fast and atomic.
  3. 3Faker plus Click options make sample data both realistic and configurable from the terminal.

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