Search & Display Results From Database (Python Flask)

Welcome to a tutorial on how to search and display results from the database using Python Flask and SQLite. So you need to add a search box to your website? Well, it actually a 2-steps process in the simplest design.

Yep, that’s all. But just how is this done exactly? Let us walk through an example in this guide – Read on!

 

 

TABLE OF CONTENTS

 

 

EXAMPLE CODE DOWNLOAD

Source code on GitHub Gist

Just click on “download zip” or do a git clone. I have released it under the MIT license, so feel free to build on top of it or use it in your own project.

 

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QUICK SETUP

• Create a virtual environment virtualenv venv and activate it – venv\Scripts\activate (Windows) venv/bin/activate (Linux/Mac)
• Install required libraries – pip install flask
• For those who are new, the default Flask folders are –
  • static Public files (JS/CSS/images/videos/audio)
  • templates HTML pages

 

 

STEP 1) THE DATABASE

1A) DUMMY USERS TABLE

-- (A) USERS TABLE
CREATE TABLE users (
  uid INTEGER,
  name TEXT NOT NULL,
  email TEXT NOT NULL,
  tel TEXT NOT NULL,
  PRIMARY KEY("uid" AUTOINCREMENT)
);
 
CREATE INDEX `idx_name`
  ON `users` (`name`);

CREATE UNIQUE INDEX `idx_email`
  ON `users` (`email`);
 
-- (B) DUMMY DATA
INSERT INTO "users" VALUES
(1,'Jo Doe','jo@doe.com','465785'),
(2,'Joa Doe','joa@doe.com','123456'),
(3,'Job Doe','job@doe.com','234567'),
(4,'Joe Doe','joe@doe.com','345678'),
(5,'Jog Doe','jog@doe.com','578456'),
(6,'Joh Doe','joh@doe.com','378945'),
(7,'Joi Doe','joi@doe.com','456789'),
(8,'Jon Doe','jon@doe.com','987654'),
(9,'Jor Doe','jor@doe.com','754642'),
(10,'Joy Doe','joy@doe.com','124578');

For a start, here is a simple dummy user table and data.

• uid User ID. Primary key and auto-increment.
• name The user’s name, indexed.
• email The user’s email, unique.
• tel Telephone number.

 

 

1B) CREATE THE DATABASE

# (A) LOAD PACKAGES
import sqlite3, os
from sqlite3 import Error

# (B) DATABASE + SQL FILE
DBFILE = "users.db"
SQLFILE = "S1A_users.sql"

# (C) DELETE OLD DATABASE IF EXIST
if os.path.exists(DBFILE):
  os.remove(DBFILE)

# (D) IMPORT SQL
conn = sqlite3.connect(DBFILE)
with open(SQLFILE) as f:
  conn.executescript(f.read())
conn.commit()
conn.close()
print("Database created!")

Not much of a mystery here. We read S1A_users.sql and create the actual database file users.db.

 

STEP 2) FLASK SERVER

2A) MODULES & SETTINGS

# (A) INIT
# (A1) LOAD MODULES
from flask import Flask, render_template, request, make_response
import sqlite3
 
# (A2) FLASK SETTINGS + INIT
HOST_NAME = "localhost"
HOST_PORT = 80
DBFILE = "users.db"
app = Flask(__name__)
# app.debug = True
 
# (B) HELPER FUNCTION - SEARCH USERS
def getusers(search):
  conn = sqlite3.connect(DBFILE)
  cursor = conn.cursor()
  cursor.execute(
    "SELECT * FROM `users` WHERE `name` LIKE ? OR `email` LIKE ?",
    ("%"+search+"%", "%"+search+"%",)
  )
  results = cursor.fetchall()
  conn.close()
  return results

The top half of the Flask server script shouldn’t need a lot of explanation.

• (A) Load the required modules and define a bunch of server settings.
• (B) A helper function to do a search on the user database.

 

 

2B) VIEWS

# (C) DEMO SEARCH PAGE
@app.route("/", methods=["GET", "POST"])
def index():
  # (C1) SEARCH FOR USERS
  if request.method == "POST":
    data = dict(request.form)
    users = getusers(data["search"])
  else:
    users = []
 
  # (C2) RENDER HTML PAGE
  return render_template("S3_users.html", usr=users)
 
# (D) START
if __name__ == "__main__":
  app.run(HOST_NAME, HOST_PORT)

No need to panic, we are only serving a single page at / here. Take a look at how this works.

• (C1) When the HTML search form is submitted, we will use the helper function getusers() to do the database search.
• (C2) We pass the search results into the HTML template for rendering.
• (D) Start the Flask server. Captain Obvious at your service.

 

STEP 3) HTML SEARCH PAGE

<!-- (A) SEARCH FORM -->
<form method="post">
  <input type="text" name="search" required>
  <input type="submit" value="Search">
</form>
 
<!-- (B) OUTPUT SEARCH RESULTS -->
{% if usr | length != 0 %}
<table id="demo">
  {% for u in usr %}
  <tr>
    <td>{{ u[0] }}</td>
    <td>{{ u[1] }}</td>
    <td>{{ u[2] }}</td>
  </tr>
  {% endfor %}
</table>
{% else %}
<div id="demo">No search results.</div>
{% endif %}

Finally, the HTML page itself. It’s nothing more than a “regular search form”, and we generate the search results in a table.

 

 

 

INDEX YOUR SEARCHABLE FIELDS!

As you can see, we have created an index on the name and email columns in this example – CREATE INDEX `NAME` ON `TABLE` (`COL`). Many beginners will probably brush this aside and not think too much about the “confusing index”.

To set things straight – Indexes are important when it comes to search performance. In layman’s terms, it’s like creating a book catalog for a library. Is searching book-by-book faster? Or referring to the catalog faster? The answer is obvious, so always index your searchable columns.

 

ADOPT A “BETTER” DATABASE

Yes, SQLite works great. It is convenient and does not require any installation. But it will eventually run into performance and security issues in a cloud (Internet/Intranet) environment. So take your time to pick up a “professional database” – MySQL, MSSQL, PostgreSQL, MongoDB, and whatever else. It is not as difficult as some think, and it is beneficial for you in the long run.

 

LINKS & REFERENCES

• Python Flask
• SQLite Where – SQLite Tutorial