Jinja2

1. Data Manipulation in Templates

{{ user.name.title() }}

Explanation: Modifies user's name to uppercase and concatenates it.

2. Conditional Statements


<div data-gb-custom-block data-tag="if">

  <p>Administrator</p>

<div data-gb-custom-block data-tag="else"></div>

  <p>User</p>

</div>

Explanation: Displays "Administrator" if the user is an admin, otherwise "User".

3. Loops and Iterations


<div data-gb-custom-block data-tag="for">

  <div>{{ post.title }}</div>

</div>

Explanation: Loops through a list of posts and displays the title for each post.

4. Data Filtering


<div data-gb-custom-block data-tag="set" data-attribute='created_date'></div>

Explanation: Sorts a list of posts based on creation date.

5. Custom Filters

@app.template_filter('duration')
def duration_filter(value):
    """Formats a duration in minutes into human-readable format."""
    return f"{value // 60}h {value % 60}m"

Explanation: Defines a custom filter to format a duration in minutes.

6. Macros


<div data-gb-custom-block data-tag="macro">

  <div>
    <h2>{{ post.title }}</h2>
    <p>{{ post.content }}</p>
  </div>

</div>

Explanation: Defines a reusable block that renders a post's title and content.

7. Includes


<div data-gb-custom-block data-tag="include" data-0='includes/sidebar.html'></div>

Explanation: Includes another template file into the current one.

8. Inheritance


<div data-gb-custom-block data-tag="extends" data-0='base.html'></div>

<div data-gb-custom-block data-tag="block">

  <h1>Home</h1>

</div>

Explanation: Creates a template that inherits the layout from a base template.

9. Static Asset Handling


<div data-gb-custom-block data-tag="static" data-0='style.css'></div>

Explanation: Generates the URL to a static asset, allowing for caching.

10. Raw Data Output

{{ post.raw_content|safe }}

Explanation: Outputs raw data without escaping, allowing for dynamic content like HTML or JavaScript.

11. URI Escaping

{{ url|uri_escape }}

Explanation: Escapes a URL string to protect against XSS attacks.

12. HTML Escape

{{ post.title|escape }}

Explanation: Escapes HTML characters to prevent cross-site scripting.

13. Date Manipulation


<div data-gb-custom-block data-tag="set"></div>

{{ now.strftime('%Y-%m-%d') }}

Explanation: Formats the current time using a specific date format.

14. Mathematical Operations

{{ a + 5 }}

Explanation: Performs mathematical operations on template variables.

15. Exception Handling


<div data-gb-custom-block data-tag="try">

  {{ undefined_variable }}

<div data-gb-custom-block data-tag="except"></div>

  {{ e }}

</div>

Explanation: Catches Jinja2 exceptions and allows for error handling.

16. Default Values

{{ user.name|default('John Doe') }}

Explanation: Provides a default value if a variable is undefined.

17. URL Building


<div data-gb-custom-block data-tag="set" data-0='view_post' data-1='view_post'></div>

Explanation: Generates a URL for a specific route.

18. Form Rendering

<form action="{{ url_for('submit_form') }}" method="POST">
  <input type="text" name="name" />
</form>

Explanation: Renders a HTML form with the specified action and method.

19. Delimiters

{# Comment using jinja delimiters #}

Explanation: Allows comments to be written within Jinja2 templates.

20. Unicode Handling

{{ "你好"|to_unicode }}

Explanation: Converts a string to unicode to handle non-ASCII characters.

21. Iteration Over Attributes


<div data-gb-custom-block data-tag="for">

  {{ key }}: {{ value }}

</div>

Explanation: Loops over the attributes of a dictionary object.

22. Dictionaries in Templates

{{ dict.keys()|list }}

Explanation: Retrieves a list of keys from a dictionary.

23. Callback Function Execution

{{ callback(arg1, arg2) }}

Explanation: Calls a specified callback function with arguments.

24. String Joins

{{ ",".join(list) }}

Explanation: Concatenates elements of a list into a string using the specified separator.

25. Object Attributes as Variables


<div data-gb-custom-block data-tag="set"></div>

Explanation: Assigns an object attribute to a template variable.

26. Function Arguments

{{ square(x) }}

Explanation: Calls a function with a specified argument.

27. Variable Assignment


<div data-gb-custom-block data-tag="set" data-x='5'></div>

Explanation: Assigns a value to a template variable.

28. Comparison Operators


<div data-gb-custom-block data-tag="if">

  ...

</div>

Explanation: Compares template variables using comparison operators.

29. Regular Expression Matching


<div data-gb-custom-block data-tag="if" data-0='[a-z]+' data-1='[a-z]+'>

  ...

</div>

Explanation: Checks if a string matches a regular expression.

30. Boolean Operations


<div data-gb-custom-block data-tag="if">

  ...

</div>

Explanation: Performs boolean operations on template variables.

31. List Operations

{{ list.sort() }}

Explanation: Sorts a list in-place.

32. Dictionary Operations

{{ dict.get('key', default_value) }}

Explanation: Retrieves a value from a dictionary, returning a default value if the key is not found.

33. Formatted String Literal

{{ f"Hello, {name}!" }}

Explanation: Formats a string using the f-string syntax.

34. Call a Class Method

{{ object.method(argument) }}

Explanation: Calls a method on an object and passes an argument.

35. Access a Class Attribute

{{ object.attribute }}

Explanation: Accesses an attribute of a class.

36. Create an Object

{{ object = Class(argument) }}

Explanation: Creates an object of a class and passes an argument.

37. Loop Over a Range


<div data-gb-custom-block data-tag="for" data-0='5' data-1='5' data-2='5' data-3='5' data-4='5' data-5='5' data-6='5' data-7='5' data-8='5' data-9='5' data-10='5' data-11='5'>

  {{ i }}

</div>

Explanation: Iterates through a range of numbers.

38. Check if Variable is Defined


<div data-gb-custom-block data-tag="if">

  ...

</div>

Explanation: Verifies whether a variable is defined.

39. Load a Template from a File


<div data-gb-custom-block data-tag="from" data-0='path/to/template.html'></div>

Explanation: Imports a template from a file and makes all its variables available.

40. Assign a Template Variable to Global Namespace


<div data-gb-custom-block data-tag="set"></div>

Explanation: Assigns a variable to the global namespace, making it available throughout the application.

41. Access Environment Variables

{{ getenv('USER') }}

Explanation: Retrieves an environment variable.

42. Call a Callback Function with Keyword Arguments

{{ callback(arg1=1, arg2='value') }}

Explanation: Calls a callback function with specific keyword arguments.

43. Execute Custom Code


<div data-gb-custom-block data-tag="with" data-0='README.md'>

  {{ f.read() }}

</div>

Explanation: Executes custom Python code within the template.

44. Create a Custom Context


<div data-gb-custom-block data-tag="with" data-0='Alice' data-name='Alice'>

  ...

</div>

Explanation: Creates a temporary context with modified values.

45. Access Function Annotations


<div data-gb-custom-block data-tag="set" data-0='input_type' data-1='input_type' data-2='input_type' data-3='input_type'></div>

Explanation: Retrieves the type annotation for a function input parameter.

46. Call a Function with Positional Arguments

{{ function(1, 'value', True) }}

Explanation: Calls a function with positional arguments.

47. Index into a List or Tuple

{{ list[index] }}

Explanation: Accesses an element of a list or tuple using an index.

48. Slice a List or Tuple

{{ list[start:end] }}

Explanation: Slices a list or tuple to create a new list or tuple.

49. Get the Length of a List or Tuple

{{ len(list) }}

Explanation: Retrieves the number of elements in a list or tuple.

50. Combine Multiple Templates


<div data-gb-custom-block data-tag="include" data-0='header.html'></div>

<div data-gb-custom-block data-tag="include" data-0='content.html'></div>

<div data-gb-custom-block data-tag="include" data-0='footer.html'></div>

Explanation: Combines multiple templates into a single cohesive template.

51. Access a Dictionary Value

{{ dictionary['key'] }}

Explanation: Retrieves the value associated with a key in a dictionary.

52. Get the Keys of a Dictionary

{{ dictionary.keys() }}

Explanation: Retrieves a list of the keys in a dictionary.

53. Get the Values of a Dictionary

{{ dictionary.values() }}

Explanation: Retrieves a list of the values in a dictionary.

54. Check if a Key Exists in a Dictionary


<div data-gb-custom-block data-tag="if" data-0='key'>

  ...

</div>

Explanation: Checks if a key exists in a dictionary.

55. Iterate Over a Dictionary


<div data-gb-custom-block data-tag="for">

  ...

</div>

Explanation: Iterates over the key-value pairs in a dictionary.

56. Get the First Item in a List or Tuple

{{ list[0] }}

Explanation: Retrieves the first item in a list or tuple.

57. Get the Last Item in a List or Tuple

{{ list[-1] }}

Explanation: Retrieves the last item in a list or tuple.

58. Reverse a List or Tuple

{{ list[::-1] }}

Explanation: Creates a new list or tuple with the elements in reverse order.

59. Sort a List or Tuple

{{ list.sort() }}

Explanation: Sorts a list or tuple in place.

60. Filter a List or Tuple

{{ list|filter(lambda item: item > 0) }}

Explanation: Creates a new list or tuple containing only the items that pass a filter condition.

61. Map a List or Tuple

{{ list|map(lambda item: item + 1) }}

Explanation: Creates a new list or tuple by applying a function to each item in the original list or tuple.

62. Combine Multiple Lists or Tuples

{{ list1 + list2 }}

Explanation: Combines multiple lists or tuples into a single list or tuple.

63. Check if a Value is in a List or Tuple


<div data-gb-custom-block data-tag="if">

  ...

</div>

Explanation: Checks if a value is contained in a list or tuple.

64. Create a Set

{{ set() }}

Explanation: Creates a new empty set.

65. Add an Item to a Set

{{ set.add(item) }}

Explanation: Adds an item to a set.

66. Iterate Over a Set


<div data-gb-custom-block data-tag="for">

  ...

</div>

Explanation: Iterates over the items in a set.

67. Check if a Set Contains an Item


<div data-gb-custom-block data-tag="if">

  ...

</div>

Explanation: Checks if a set contains a specific item.

68. Intersect Two Sets

{{ set1.intersection(set2) }}

Explanation: Creates a new set containing the elements that are common to both sets.

69. Union Two Sets

{{ set1.union(set2) }}

Explanation: Creates a new set containing all the elements from both sets.

70. Difference Between Two Sets

{{ set1.difference(set2) }}

Explanation: Creates a new set containing the elements that are in set1 but not in set2.

71. Symmetric Difference Between Two Sets

{{ set1.symmetric_difference(set2) }}

Explanation: Creates a new set containing the elements that are in either set1 or set2 but not in both.

72. Create a Frozen Set

{{ frozenset() }}

Explanation: Creates a new frozen set.

73. Iterate Over a Frozen Set


<div data-gb-custom-block data-tag="for">

  ...

</div>

Explanation: Iterates over the items in a frozen set.

74. Check if a Frozen Set Contains an Item


<div data-gb-custom-block data-tag="if">

  ...

</div>

Explanation: Checks if a frozen set contains a specific item.

75. Convert a Set to a List

{{ list(set) }}

Explanation: Converts a set to a list.

76. Convert a Tuple to a List

{{ list(tuple) }}

Explanation: Converts a tuple to a list.

77. Convert a Dictionary to a List of Tuples

{{ list(dictionary.items()) }}

Explanation: Converts a dictionary to a list of tuples, where each tuple represents a key-value pair.

78. Convert a Dictionary to a List of Lists

{{ list(dictionary.values()) }}

Explanation: Converts a dictionary to a list of lists, where each list contains the values for a key in the dictionary.

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