IIT M IMPROVEMENT AN EXAM QID4 26 Oct - 26 Oct 2025

Concepts this paper tests

Auto-generated summary from the source site. Handy as a checklist; the lessons above explain each idea from scratch.

Here’s a structured summary of the core topics, concepts, principles, and equations (where applicable) for the Diploma Level: Modern Application Development I (Computer-Based Exam). This exam focuses on Flask, Jinja2, HTML/CSS, HTTP, and Python templating.

Core Topics & Concepts

1. Flask (Python Web Framework)

• Routing:

  • Define routes using @app.route('/path').
  • Dynamic routes with variables: @app.route('/profile/<username>').
  • Query parameters: Accessed via request.args.get('param').
  • HTTP methods: @app.route('/', methods=['GET', 'POST']).
  • 404 Errors: Occur when a URL doesn’t match any route.

  • Example:

    @app.route('/user')
    def user():
        username = request.args.get('username')  # Query param
        return f"Hello, {username}"

• Request Handling:

  • request.method: Check if GET, POST, etc.
  • request.form: Access form data (for POST requests).
  • request.args: Access query parameters (for GET requests).

• Running the Server:

  • app.run(port=5000, debug=True).
  • Default port: 5000; customizable (e.g., 5008).
  • URLs: http://localhost:port or http://127.0.0.1:port.

• Common Errors:

  • 404 Not Found: No matching route.
  • 405 Method Not Allowed: HTTP method not supported for the route.
  • KeyError: Missing query/form parameter.

• Key Equations/Logic:

  • URL Structure: protocol://host:port/path?query_params Example: http://localhost:5000/user?username=alice
  • Route Matching: /profile/<username>/active/<year> matches /profile/alice/active/2024.

2. Jinja2 (Templating Engine)

• Syntax:

  • Variables: {{ variable }}.
  • Filters: {{ list | length }} or {{ list | len }} (note: length is correct in Jinja2; len is a Python function).

  • Control structures:

    {% if condition %} ... {% endif %}
    {% for item in list %} ... {% endfor %}

• Template Rendering:

  • render_template('file.html', var=value).
  • render_template_string("Hello, {{ name }}", name="Alice").

• Inheritance:

  • {% extends 'base.html' %} and {% block content %}...{% endblock %}.
• Key Differences: | Feature | Jinja2 | Python string.Template | |------------------|---------------------------------|---------------------------------| | Syntax | {{ var }} | ${var} or $var | | Filters | {{ list | length }} | No built-in filters | | Logic | {% if %}, {% for %} | No logic; substitution only |

3. HTML/CSS

• Block vs. Inline Elements: | Block Elements | Inline Elements | |----------------------|------------------------| | <div>, <p> | <span>, <strong> | | Start on new line | Flow inline | | Full width | Width as per content |

• Box Model:

  • Total Width Calculation: width + padding-left + padding-right + border-left + border-right + margin-left + margin-right Example:

    .container {
        width: 200px;
        padding: 15px;       /* 15px left + 15px right = 30px */
        border: 5px solid;   /* 5px left + 5px right = 10px */
        margin: 10px;         /* Excluded from total width */
    }

    Total width = 200 + 30 + 10 = 240px (excluding margin).

• Image Tag:

  • <img src="path" alt="text">.
  • alt text is shown if the image fails to load.

4. HTTP Protocol

• URL Structure: http://localhost:5000/path?query=value

  • http: Protocol.
  • localhost: Host.
  • 5000: Port.
  • /path: Route.
  • ?query=value: Query parameters.

• HTTP Methods:

  • GET: Retrieve data (query params).
  • POST: Submit data (form body).
  • PUT: Update data.
  • DELETE: Remove data.

• Status Codes:

  • 200 OK: Success.
  • 404 Not Found: Route doesn’t exist.
  • 405 Method Not Allowed: HTTP method not supported.

5. Python Templating

• Jinja2 vs. string.Template:

  • Jinja2: Supports logic, filters, and inheritance.
  • string.Template: Simpler, uses $var or ${var}.

  • Example:

    from jinja2 import Template as JTemplate
    from string import Template as STemplate
    jt = JTemplate("{{ name }}")  # Jinja2
    st = STemplate("$name")       # string.Template

• Rendering Workflow:

  1. User submits form (POST request).
  2. Flask handles the request (request.form).
  3. Jinja2 renders the template with dynamic data.

6. Command-Line Arguments

• sys.argv:

  • sys.argv[0]: Script name.
  • sys.argv[1:]: Command-line arguments.

  • Example:

    # python script.py arg1 arg2
    print(sys.argv[0])  # script.py
    print(sys.argv[1])  # arg1

7. Flask Errors & Debugging

• Common Issues:

  1. Route Mismatch:

     • @app.route('/login', method='GET') → Should be methods=['GET'].

  2. Missing Parameters:

     • def login(id): but no id in the URL.

  3. Incorrect HTTP Methods:

     • curl -X POST to a route that only allows GET.

• Debugging:

  • Run Flask with debug=True for detailed errors.
  • Check request.method and route definitions.

Key Equations/Calculations

1. CSS Box Model Total Width: `` total_width = width + padding_left + padding_right + border_left + border_right ` Example: ` width = 200px, padding = 15px, border = 5px total_width = 200 + 15 + 15 + 5 + 5 = 240px ``

1. URL Query Parameters: `` http://host:port/path?key1=value1&key2=value2 ` Access in Flask: `python value1 = request.args.get('key1') ``

Graph 2: Jinja2 vs. string.Template

Graph 3: HTML/CSS Concepts

Graph 4: HTTP Workflow in Flask

Graph 5: Python Templating Comparison