Task results and status in Django - Step-by-Step Execution

Concept Flow - Task results and status

Start Task

↓

Task Running

↓

Task Completes?

No→Wait or Retry

Yes↓

Store Result & Status

↓

Check Status & Result

↓

Display or Use Result

This flow shows how a task starts, runs, completes, stores its result and status, and then how the status and result are checked or displayed.

Execution Sample

Django

from django_q.tasks import async_task

# Start a task
async_task('math.copysign', 1, -1)

# Later check status and result
from django_q.models import Task
result = Task.objects.last().result
status = Task.objects.last().success

This code starts an asynchronous task and later retrieves its result and success status from the database.

Execution Table

Step	Action	Task Status	Result Stored	Notes
1	Call async_task to start task	Pending	None	Task is queued to run asynchronously
2	Task starts running	Running	None	Task is executing the function
3	Task completes successfully	Success	-1.0	Result of math.copysign(1, -1) stored
4	Retrieve last task from DB	Success	-1.0	Access task status and result
5	Use result and status	Success	-1.0	Result -1.0 and success True used in app
6	No new tasks	N/A	N/A	Execution stops here

💡 No more tasks to process, final status and result stored

Variable Tracker

Variable	Start	After Step 1	After Step 3	After Step 4	Final
task_status	None	Pending	Success	Success	Success
task_result	None	None	-1.0	-1.0	-1.0

Key Moments - 3 Insights

Why is the task status 'Pending' right after calling async_task?

Because the task is only queued to run asynchronously and has not started execution yet, as shown in step 1 of the execution_table.

How do we know the task completed successfully?

At step 3, the status changes to 'Success' and the result is stored, indicating the task finished without errors.

Why do we retrieve the task from the database to get the result?

Because async tasks run outside the main code flow, their results and status are saved in the database for later retrieval, as shown in step 4.

Visual Quiz - 3 Questions

Look at the execution_table, what is the task status immediately after calling async_task?

A Running

B Pending

C Success

D Failed

💡 Hint

Check step 1 in the execution_table where the task is just queued.

At which step does the task result get stored?

A Step 2

B Step 4

C Step 3

D Step 5

💡 Hint

Look for when the result value changes from None to -1.0 in the variable_tracker and execution_table.

If the task failed, what would you expect the 'task_status' to be at step 3?

A Failed

B Running

C Pending

D Success

💡 Hint

Refer to the meaning of status values in the execution_table and key_moments.

Concept Snapshot

Task results and status in Django Q:
- async_task() queues a task (status: Pending)
- Task runs asynchronously (status: Running)
- On completion, result and status saved (Success or Failed)
- Retrieve task from DB to check status and result
- Use status to handle success or failure in your app

Full Transcript

In Django Q, when you start a task with async_task, it is first queued with status Pending. Then the task runs asynchronously and its status changes to Running. When the task finishes, the result and status (Success or Failed) are saved in the database. You can later retrieve the task object from the database to check its status and get the result. This lets your app know if the task succeeded and what output it produced.