Task status monitoring in Flask - Mini Project: Build & Apply

Task status monitoring

📖 Scenario: You are building a simple program to monitor the status of tasks in a project. Each task has a name and a status like 'pending', 'in progress', or 'done'. You want to create a small program that keeps track of tasks and shows how many tasks are done.

🎯 Goal: Build a program that stores tasks in a dictionary, sets a status filter, counts how many tasks are done, and displays the count.

📋 What You'll Learn

Create a dictionary called tasks with exact task names and statuses

Create a variable called status_filter with the value 'done'

Use a list comprehension to create a list of tasks with status matching status_filter

Print the count of tasks that are done

💡 Why This Matters

🌍 Real World

Monitoring task statuses helps teams track progress and identify completed work quickly.

💼 Career

Understanding how to filter and count tasks is useful for building dashboards and status reports in DevOps and project management roles.

1

Create the tasks dictionary

Create a dictionary called tasks with these exact entries: 'task1': 'pending', 'task2': 'done', 'task3': 'in progress', 'task4': 'done'

Flask

# Your code here

Hint

Use curly braces to create a dictionary with keys as task names and values as their statuses.

2

Set the status filter

Create a variable called status_filter and set it to the string 'done'

Flask

tasks = {'task1': 'pending', 'task2': 'done', 'task3': 'in progress', 'task4': 'done'}
# Your code here

Hint

Just assign the string 'done' to the variable status_filter.

3

Filter tasks by status

Use a list comprehension to create a list called done_tasks that contains the names of tasks from tasks where the status equals status_filter

Flask

tasks = {'task1': 'pending', 'task2': 'done', 'task3': 'in progress', 'task4': 'done'}
status_filter = 'done'
# Your code here

Hint

Use tasks.items() to get task and status pairs, then filter by status_filter.

4

Print the count of done tasks

Print the number of tasks in done_tasks using print(len(done_tasks))

Flask

tasks = {'task1': 'pending', 'task2': 'done', 'task3': 'in progress', 'task4': 'done'}
status_filter = 'done'
done_tasks = [task for task, status in tasks.items() if status == status_filter]
# Your code here

Hint

Use len() to get the count of items in the list and print it.

Practice

1. What is the main purpose of task status monitoring in a Flask application?

easy

A. To store user login credentials securely

B. To speed up the Flask server response time

C. To let users see the progress of background jobs

D. To automatically restart the Flask app on errors

Solution

1. Step 1: Understand task status monitoring

   Task status monitoring is about showing users how background jobs are progressing.

2. Step 2: Identify the correct purpose

   Among the options, only letting users see job progress matches the purpose.

3. Final Answer:

   To let users see the progress of background jobs -> Option C

4. Quick Check:

   Task status monitoring = show job progress [OK]

Hint: Task status monitoring shows job progress to users [OK]

Common Mistakes:

• Confusing task monitoring with server speed optimization
• Thinking it manages user authentication
• Assuming it restarts the app automatically

2. Which Flask route method is best to check the status of a running background task?

easy

A. POST

B. GET

C. DELETE

D. PUT

Solution

1. Step 1: Understand HTTP methods for status checking

   GET is used to retrieve information without changing server state.

2. Step 2: Match method to task status check

   Checking task status is a read operation, so GET is appropriate.

3. Final Answer:

   GET -> Option B

4. Quick Check:

   Check status = GET request [OK]

Hint: Use GET to fetch status without changing data [OK]

Common Mistakes:

• Using POST which changes data
• Choosing DELETE which removes data
• Using PUT which updates data

3. Given this Flask code snippet, what will be the output when accessing /status/task1 if tasks = {'task1': 'running'}?

from flask import Flask, jsonify
app = Flask(__name__)
tasks = {'task1': 'running'}

@app.route('/status/<task_id>')
def status(task_id):
    state = tasks.get(task_id, 'not found')
    return jsonify({'task': task_id, 'status': state})

medium

A. {"task": "task1", "status": "running"}

B. {"task": "task1", "status": "not found"}

C. 404 Not Found error

D. SyntaxError

Solution

1. Step 1: Check the tasks dictionary for 'task1'

   The dictionary has 'task1' with value 'running'.

2. Step 2: Understand the route function output

   The function returns JSON with task id and its status from the dictionary.

3. Final Answer:

   {"task": "task1", "status": "running"} -> Option A

4. Quick Check:

   tasks['task1'] = running [OK]

Hint: Check dictionary key presence for status [OK]

Common Mistakes:

• Assuming missing key returns error instead of default
• Confusing JSON string with Python dict
• Expecting 404 error without explicit handling

4. Identify the error in this Flask route for checking task status:

@app.route('/status/<task_id>')
def status(task_id):
    state = tasks[task_id]
    return {'task': task_id, 'status': state}

medium

A. Using tasks[task_id] without checking if key exists

B. Returning a dictionary instead of JSON response

C. Missing @app.route decorator

D. Incorrect route URL syntax

Solution

1. Step 1: Analyze dictionary access

   Accessing tasks[task_id] without checking key causes KeyError if missing.

2. Step 2: Confirm other parts are correct

   Returning dict is allowed by Flask; decorator and route syntax are correct.

3. Final Answer:

   Using tasks[task_id] without checking if key exists -> Option A

4. Quick Check:

   Direct dict access risks KeyError [OK]

Hint: Always check dict keys before access to avoid errors [OK]

Common Mistakes:

• Thinking returning dict is wrong in Flask
• Ignoring possible KeyError on missing keys
• Assuming route decorator is missing

5. You want to monitor multiple background tasks in Flask and update their status safely. Which approach is best to store and update task states?

hard

A. Store task states only in local variables inside routes

B. Store task states in a file without synchronization

C. Use print statements to track task progress in console

D. Use a global dictionary with thread locks to store task states

Solution

1. Step 1: Consider concurrency in Flask background tasks

   Multiple tasks may update states concurrently, so thread safety is needed.

2. Step 2: Evaluate storage options

   Global dictionary with thread locks ensures safe updates; local vars or files without sync cause errors.

3. Final Answer:

   Use a global dictionary with thread locks to store task states -> Option D

4. Quick Check:

   Safe shared state needs locks [OK]

Hint: Use locks with shared dict for safe task status updates [OK]

Common Mistakes:

• Using local variables which don't persist
• Ignoring thread safety causing race conditions
• Relying on print statements for monitoring