Trigger types (HTTP, Timer, Blob, Queue) in Azure - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define an HTTP trigger function in Azure Functions.

Azure

def main(req: func.HttpRequest) -> func.HttpResponse:
    if req.method == '[1]':
        return func.HttpResponse('Hello HTTP!')

Drag options to blanks, or click blank then click option'

ADELETE

BPOST

CPUT

DGET

Attempts:

3 left

💡 Hint

Common Mistakes

Using POST instead of GET for simple retrieval.

The HTTP trigger listens for HTTP requests. The most common method to respond to is GET.

2fill in blank

medium

Complete the code to set a Timer trigger schedule to run every 5 minutes.

Azure

timer = func.TimerRequest(schedule='[1]')

Drag options to blanks, or click blank then click option'

A0 */5 * * * *

B*/5 * * * *

C5 * * * *

D0 5 * * * *

Attempts:

3 left

💡 Hint

Common Mistakes

Using 5-field cron expressions missing the seconds field.

The cron expression 0 */5 * * * * means every 5 minutes at second 0.

3fill in blank

hard

Fix the error in the Blob trigger binding path to listen to the container named 'images'.

Azure

blob_trigger = func.InputStream('[1]/{name}')

Drag options to blanks, or click blank then click option'

Aimages

Bimage

Cimage-container

Dimg

Attempts:

3 left

💡 Hint

Common Mistakes

Using singular or incorrect container names.

The binding path must match the exact container name, which is images.

4fill in blank

hard

Fill both blanks to define a Queue trigger function that listens to the 'tasks' queue and uses the correct parameter type.

Azure

def main(msg: [1]):
    logging.info(f'Received message: {msg.[2]')

Drag options to blanks, or click blank then click option'

Afunc.QueueMessage

Bfunc.QueueTrigger

Cfunc.QueueItem

Dcontent

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect parameter types or accessing wrong attributes.

The parameter type for a Queue trigger message is func.QueueMessage, and the message content is accessed via the content attribute.

5fill in blank

hard

Fill all three blanks to define an HTTP triggered Azure Function that reads a query parameter 'name' and returns a greeting.

Azure

def main(req: func.HttpRequest) -> func.HttpResponse:
    name = req.params.get('[1]')
    if not name:
        try:
            req_body = req.get_json()
        except ValueError:
            pass
        else:
            name = req_body.get('[2]')
    if name:
        return func.HttpResponse(f'Hello, [3]!')
    else:
        return func.HttpResponse('Please pass a name on the query string or in the request body.', status_code=400)

Drag options to blanks, or click blank then click option'

Aname

Busername

Duser

Attempts:

3 left

💡 Hint

Common Mistakes

Using different keys for query and JSON, or wrong variable in greeting.

The query parameter and JSON key are both 'name', and the greeting uses the variable name.

Practice

1. Which Azure Function trigger type starts a function when a web request is received?

easy

A. Queue trigger

B. Timer trigger

C. HTTP trigger

D. Blob trigger

Solution

1. Step 1: Understand trigger types

   HTTP triggers start functions when they receive web requests.

2. Step 2: Match trigger to event

   Since the question asks about web requests, HTTP trigger is the correct match.

3. Final Answer:

   HTTP trigger -> Option C

4. Quick Check:

   Web request triggers = HTTP trigger [OK]

Hint: Web requests always use HTTP triggers [OK]

Common Mistakes:

• Confusing Timer with HTTP
• Thinking Blob triggers handle web requests
• Mixing Queue triggers with HTTP

2. Which of the following is the correct way to define a Timer trigger in Azure Functions using function.json?

easy

A. {"bindings": [{"type": "timerTrigger", "direction": "in", "name": "myTimer", "schedule": "0 */5 * * * *"}]}

B. {"bindings": [{"type": "httpTrigger", "direction": "in", "name": "req"}]}

C. {"bindings": [{"type": "blobTrigger", "direction": "in", "name": "myBlob", "path": "samples-workitems/{name}"}]}

D. {"bindings": [{"type": "queueTrigger", "direction": "in", "name": "myQueueItem", "queueName": "myqueue-items"}]}

Solution

1. Step 1: Identify Timer trigger syntax

   Timer triggers use type "timerTrigger" and include a "schedule" property.

2. Step 2: Match JSON with Timer trigger

   {"bindings": [{"type": "timerTrigger", "direction": "in", "name": "myTimer", "schedule": "0 */5 * * * *"}]} has type "timerTrigger" and a cron schedule, matching Timer trigger format.

3. Final Answer:

   Option A JSON with timerTrigger and schedule -> Option A

4. Quick Check:

   Timer trigger needs "timerTrigger" type and schedule [OK]

Hint: Timer triggers always include a cron schedule in function.json [OK]

Common Mistakes:

• Using httpTrigger type for Timer
• Missing schedule property
• Confusing Blob or Queue trigger syntax

3. Given this Azure Function code snippet using a Queue trigger:

public static void Run([QueueTrigger("myqueue-items")] string myQueueItem, ILogger log) {
    log.LogInformation($"Processed queue item: {myQueueItem}");
}

What will be logged when a message "Hello" is added to the queue?

medium

A. Processed queue item: Hello

B. Processed queue item: myqueue-items

C. Queue trigger error

D. No log output

Solution

1. Step 1: Understand Queue trigger behavior

   The function runs when a message arrives in "myqueue-items" queue, passing the message content as myQueueItem.

2. Step 2: Analyze log output

   The log prints "Processed queue item: " plus the message content, which is "Hello".

3. Final Answer:

   Processed queue item: Hello -> Option A

4. Quick Check:

   Queue message content logged = "Processed queue item: Hello" [OK]

Hint: Queue trigger passes message content as parameter [OK]

Common Mistakes:

• Logging queue name instead of message
• Expecting error without cause
• Assuming no output from trigger

4. You wrote this Azure Function with a Blob trigger:

public static void Run([BlobTrigger("samples-workitems/{name}")] Stream myBlob, string name, ILogger log) {
    log.LogInformation($"Blob name: {name}, Size: {myBlob.Length} bytes");
}

But the function never runs when you upload blobs. What is the most likely cause?

medium

A. Blob triggers require HTTP requests to start

B. The Blob trigger path is incorrect or container name is wrong

C. The function is missing a Timer trigger

D. The function must use Queue trigger instead

Solution

1. Step 1: Check Blob trigger path

   The Blob trigger listens to a specific container path; if the container name or path is wrong, it won't trigger.

2. Step 2: Eliminate other causes

   Timer triggers or HTTP requests are unrelated; Blob triggers respond to storage changes only.

3. Final Answer:

   The Blob trigger path is incorrect or container name is wrong -> Option B

4. Quick Check:

   Blob trigger needs correct container path to run [OK]

Hint: Blob trigger must match exact container path [OK]

Common Mistakes:

• Expecting Timer or HTTP triggers to start Blob
• Wrong container or path in BlobTrigger attribute
• Confusing Blob and Queue triggers

5. You want to run an Azure Function every day at 3 AM and also process any new files uploaded to a Blob container immediately. Which trigger types should you combine in your solution?

hard

A. HTTP trigger for schedule and Queue trigger for file uploads

B. Blob trigger for schedule and HTTP trigger for file uploads

C. Queue trigger for schedule and Timer trigger for file uploads

D. Timer trigger for schedule and Blob trigger for file uploads

Solution

1. Step 1: Identify trigger for scheduled runs

   Timer triggers run functions on schedules like daily at 3 AM.

2. Step 2: Identify trigger for file uploads

   Blob triggers respond immediately to new files uploaded to Blob storage.

3. Step 3: Combine triggers correctly

   Use Timer trigger for scheduled runs and Blob trigger for file events.

4. Final Answer:

   Timer trigger for schedule and Blob trigger for file uploads -> Option D

5. Quick Check:

   Schedule = Timer, File upload = Blob trigger [OK]

Hint: Schedule needs Timer; file events need Blob trigger [OK]

Common Mistakes:

• Using HTTP trigger for schedule
• Mixing Queue with schedule incorrectly
• Confusing Blob and HTTP triggers