Curso Django. Plantillas III. Bucles y condicionales en plantillas. Vídeo 7

Introduction to Django Templates

In this section, we will learn about calling methods from templates and the hierarchy/order of calls made from templates. We will also explore how to use lists in the context and templates.

Calling Methods from Templates

• We can call methods from templates by using the dot notation.

• The dot notation is used to access attributes or methods of an object.

• For example, we can call a method like object.method() in a template.

Using Lists in Context and Templates

• In the previous video, we learned that we can pass a dictionary as an argument in the context to handle data in templates.

• To include a list in the context, simply add it as another key-value pair in the dictionary.

• Lists can be accessed using the dot notation and index position within the template.

• To access individual elements of a list, use list_name.index where index is the position of the element (starting from 0).

Example Implementation

• We will continue working on our previous example where we displayed static and dynamic messages on a webpage.

• Now, we want to include a list of topics related to our course.

• We add the list as another key-value pair in our context dictionary.

• In our template, we can display this list using double curly braces and accessing it with its key name.

Accessing List Elements Individually

In this section, we will learn how to access individual elements of a list within a template using index positions.

Accessing List Elements

• To access individual elements of a list within a template, use dot notation followed by the index position.

• Remember that lists start counting from 0, so if you want to access the first element, use list_name.0.

• You can use this notation to display specific elements of a list in your template.

Alternative Approach: Using Variables

• Instead of directly including the entire list in the context, you can create a variable and assign the list to it.

• Then, use this variable within the context to access the list elements in your template.

• This approach can be useful when dealing with long lists or for better readability.

Understanding Dot Notation in Templates

In this section, we will explore how dot notation is used in templates for different purposes.

Multiple Uses of Dot Notation

• Dot notation is used in templates for various purposes.

• It is used to access attributes or methods of an object, as well as to access indexes of a list.

• Understanding the context and purpose of dot notation is important when working with templates.

Conclusion

In this section, we covered calling methods from templates, using lists in context and templates, accessing individual elements of a list within a template, and understanding dot notation in templates.

Understanding Django's Internal Order of Calls

In this section, the speaker explains the internal order of calls in Django and how to identify if a point is making a call to an index of a list.

Django's Internal Order of Calls

• Django follows a specific internal order of calls.

• To determine if a point is making a call to an index of a list, follow these steps:

• Check if the point appears in the internal order of calls.

• If it does, then it is making a call to an index of a list.

Displaying Multiple Topics on Webpages

This section discusses different ways to display multiple topics on webpages using Django.

Displaying Topics One Below Another

• To display topics one below another, there are several approaches:

• Create a paragraph before the current paragraph and use bold tags to highlight it.

• Use opening and closing strong tags around the text "Temas del curso" to make it bold.

• Save changes and update the webpage to see the result.

Printing All Elements from a List

This section explains how to print or display all elements that are part of a list in Django.

Printing All Elements

• One way to print all elements from a list is by copying and pasting the instruction for each element.

• Change the index value for each copied instruction accordingly.

• However, this approach generates excessive HTML code and becomes impractical for large lists.

Using Loops in Django Templates

This section demonstrates how loops can be used in Django templates to iterate over lists efficiently.

Utilizing Loops in Django Templates

• Loops can be used in Django templates to iterate over lists.

• To create a loop, follow these steps:

• Remove unnecessary tags.

• Open a new paragraph after the introduction text "Temas del curso."

• Use the for loop syntax: % for tema in temas %

• Close the for loop with % endfor %.

• Save changes and update the webpage to see the result.

Benefits of Using Loops

This section highlights the advantages of using loops instead of copying instructions when dealing with large lists.

Advantages of Using Loops

• Using loops instead of copying instructions offers several benefits:

• Reduces HTML code generation.

• Efficiently handles large lists.

• When dealing with programming tasks that require iterating over elements, loops are a preferred solution.

Syntax for Looping Over Lists

This section explains the syntax for looping over lists in Django templates.

Syntax for Looping Over Lists

• Remove unnecessary tags from previous steps.

• After the introduction text "Temas del curso," open a new paragraph and use the following syntax:

% for tema in temas %

tema

% endfor %

• Save changes and update the webpage to see the result.

Creating Ordered or Unordered Lists

This section demonstrates how to create ordered or unordered lists using HTML tags within Django templates.

Creating Lists

• Before entering the for loop, add an opening <ul> tag if creating an unordered list or <ol> tag if creating an ordered list.

• Inside each iteration of the loop, replace <p> tags with <li> tags.

• Ensure correct opening and closing brackets for the list tags.

• Save changes and update the webpage to see the result.

Formatting Lists

This section explains how to format lists in Django templates by adjusting HTML tags.

Formatting Lists

• To improve list formatting, consider adding additional HTML tags:

• Add <p> and closing </p> tags around each topic within the loop.

• Use <ul> or <ol> tags to create a single unordered or ordered list that encompasses the entire loop.

• Save changes and update the webpage to see the improved formatting.

Utilizing Loops and Conditionals

This section mentions that loops can be combined with conditionals in Django templates.

Combining Loops and Conditionals

• In addition to loops, conditionals (such as if statements) can also be used in Django templates.

• The speaker provides an example of using an if statement within a loop but does not provide further details.

Printing Conditional Messages

In this section, the speaker discusses how to print conditional messages in Django templates.

Creating a Conditional Statement

• To print a message only if there is information available, a conditional statement can be used.

• The syntax for creating a conditional statement in Django templates is similar to HTML and Python.

• Before the for loop, an opening if tag is added, followed by the condition to check.

• After the closing tag of the for loop, the closing if tag is added.

Adding an Else Statement

• To handle cases where the condition is not met, an else statement can be added after the if statement.

• The syntax for adding an else statement in Django templates is similar to HTML and Python.

• After the closing tag of the if statement, an opening else tag is added, followed by the desired action or message.

Nesting Control Structures

• Control structures like loops and conditionals can be nested within each other in Django templates.

• This allows for more complex logic and control flow within the template.

Calling Methods and Properties

In this section, the speaker explains how to call methods and properties in Django templates.

Syntax for Calling Methods and Properties

• The syntax for calling methods and properties in Django templates is similar to Python.

• Use dot notation to access methods or properties of objects.

• There are no parentheses required when calling methods or properties in Django templates.

Example: Using String Methods

• Demonstrates calling string methods like lower() and upper() on variables within a template.

• These methods can modify strings by converting them to lowercase or uppercase.

Order of Evaluation

In this section, the speaker discusses the order of evaluation in Django templates when encountering different types of elements.

Order of Evaluation

• Django templates follow a specific order of evaluation when encountering elements like dictionaries, attributes, and methods.

• The order of evaluation is as follows: dictionary, attribute, method.

• If an element is not found at one level, the template engine moves to the next level for evaluation.

Example: Calling Methods and Properties

• Demonstrates calling methods and properties in Django templates using dot notation.

• Shows how the template engine evaluates whether an element is a dictionary, attribute, or method.

Conclusion

The transcript covers two main topics: printing conditional messages and calling methods/properties in Django templates. It explains how to create conditional statements and add else statements for handling different conditions. Additionally, it clarifies the syntax for calling methods and properties within templates. The section on the order of evaluation highlights the sequence followed by Django templates when encountering different types of elements.