# Jinja2
***
**1. Data Manipulation in Templates**
```python
{{ user.name.title() }}
```
**Explanation:** Modifies user's name to uppercase and concatenates it.
**2. Conditional Statements**
```python
```
**Explanation:** Displays "Administrator" if the user is an admin, otherwise "User".
**3. Loops and Iterations**
```python
```
**Explanation:** Loops through a list of posts and displays the title for each post.
**4. Data Filtering**
```python
```
**Explanation:** Sorts a list of posts based on creation date.
**5. Custom Filters**
```python
@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**
```python
{{ post.title }}
{{ post.content }}
```
**Explanation:** Defines a reusable block that renders a post's title and content.
**7. Includes**
```python
```
**Explanation:** Includes another template file into the current one.
**8. Inheritance**
```python
Home
```
**Explanation:** Creates a template that inherits the layout from a base template.
**9. Static Asset Handling**
```python
```
**Explanation:** Generates the URL to a static asset, allowing for caching.
**10. Raw Data Output**
```python
{{ post.raw_content|safe }}
```
**Explanation:** Outputs raw data without escaping, allowing for dynamic content like HTML or JavaScript.
**11. URI Escaping**
```python
{{ url|uri_escape }}
```
**Explanation:** Escapes a URL string to protect against XSS attacks.
**12. HTML Escape**
```python
{{ post.title|escape }}
```
**Explanation:** Escapes HTML characters to prevent cross-site scripting.
**13. Date Manipulation**
```python
{{ now.strftime('%Y-%m-%d') }}
```
**Explanation:** Formats the current time using a specific date format.
**14. Mathematical Operations**
```python
{{ a + 5 }}
```
**Explanation:** Performs mathematical operations on template variables.
**15. Exception Handling**
```python
{{ undefined_variable }}
{{ e }}
{{ key }}: {{ value }}
```
**Explanation:** Loops over the attributes of a dictionary object.
**22. Dictionaries in Templates**
```python
{{ dict.keys()|list }}
```
**Explanation:** Retrieves a list of keys from a dictionary.
**23. Callback Function Execution**
```python
{{ callback(arg1, arg2) }}
```
**Explanation:** Calls a specified callback function with arguments.
**24. String Joins**
```python
{{ ",".join(list) }}
```
**Explanation:** Concatenates elements of a list into a string using the specified separator.
**25. Object Attributes as Variables**
```python
```
**Explanation:** Assigns an object attribute to a template variable.
**26. Function Arguments**
```python
{{ square(x) }}
```
**Explanation:** Calls a function with a specified argument.
**27. Variable Assignment**
```python
```
**Explanation:** Assigns a value to a template variable.
**28. Comparison Operators**
```python
...
```
**Explanation:** Compares template variables using comparison operators.
**29. Regular Expression Matching**
```python
...
```
**Explanation:** Checks if a string matches a regular expression.
**30. Boolean Operations**
```python
...
```
**Explanation:** Performs boolean operations on template variables.
**31. List Operations**
```python
{{ list.sort() }}
```
**Explanation:** Sorts a list in-place.
**32. Dictionary Operations**
```python
{{ 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**
```python
{{ f"Hello, {name}!" }}
```
**Explanation:** Formats a string using the f-string syntax.
**34. Call a Class Method**
```python
{{ object.method(argument) }}
```
**Explanation:** Calls a method on an object and passes an argument.
**35. Access a Class Attribute**
```python
{{ object.attribute }}
```
**Explanation:** Accesses an attribute of a class.
**36. Create an Object**
```python
{{ object = Class(argument) }}
```
**Explanation:** Creates an object of a class and passes an argument.
**37. Loop Over a Range**
```python
{{ i }}
```
**Explanation:** Iterates through a range of numbers.
**38. Check if Variable is Defined**
```python
...
```
**Explanation:** Verifies whether a variable is defined.
**39. Load a Template from a File**
```python
```
**Explanation:** Imports a template from a file and makes all its variables available.
**40. Assign a Template Variable to Global Namespace**
```python
```
**Explanation:** Assigns a variable to the global namespace, making it available throughout the application.
**41. Access Environment Variables**
```python
{{ getenv('USER') }}
```
**Explanation:** Retrieves an environment variable.
**42. Call a Callback Function with Keyword Arguments**
```python
{{ callback(arg1=1, arg2='value') }}
```
**Explanation:** Calls a callback function with specific keyword arguments.
**43. Execute Custom Code**
```python
{{ f.read() }}
```
**Explanation:** Executes custom Python code within the template.
**44. Create a Custom Context**
```python
...
```
**Explanation:** Creates a temporary context with modified values.
**45. Access Function Annotations**
```python
```
**Explanation:** Retrieves the type annotation for a function input parameter.
**46. Call a Function with Positional Arguments**
```python
{{ function(1, 'value', True) }}
```
**Explanation:** Calls a function with positional arguments.
**47. Index into a List or Tuple**
```python
{{ list[index] }}
```
**Explanation:** Accesses an element of a list or tuple using an index.
**48. Slice a List or Tuple**
```python
{{ 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**
```python
{{ len(list) }}
```
**Explanation:** Retrieves the number of elements in a list or tuple.
**50. Combine Multiple Templates**
```python
```
**Explanation:** Combines multiple templates into a single cohesive template.
**51. Access a Dictionary Value**
```python
{{ dictionary['key'] }}
```
**Explanation:** Retrieves the value associated with a key in a dictionary.
**52. Get the Keys of a Dictionary**
```python
{{ dictionary.keys() }}
```
**Explanation:** Retrieves a list of the keys in a dictionary.
**53. Get the Values of a Dictionary**
```python
{{ dictionary.values() }}
```
**Explanation:** Retrieves a list of the values in a dictionary.
**54. Check if a Key Exists in a Dictionary**
```python
...
```
**Explanation:** Checks if a key exists in a dictionary.
**55. Iterate Over a Dictionary**
```python
...
```
**Explanation:** Iterates over the key-value pairs in a dictionary.
**56. Get the First Item in a List or Tuple**
```python
{{ list[0] }}
```
**Explanation:** Retrieves the first item in a list or tuple.
**57. Get the Last Item in a List or Tuple**
```python
{{ list[-1] }}
```
**Explanation:** Retrieves the last item in a list or tuple.
**58. Reverse a List or Tuple**
```python
{{ list[::-1] }}
```
**Explanation:** Creates a new list or tuple with the elements in reverse order.
**59. Sort a List or Tuple**
```python
{{ list.sort() }}
```
**Explanation:** Sorts a list or tuple in place.
**60. Filter a List or Tuple**
```python
{{ 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**
```python
{{ 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**
```python
{{ 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**
```python
...
```
**Explanation:** Checks if a value is contained in a list or tuple.
**64. Create a Set**
```python
{{ set() }}
```
**Explanation:** Creates a new empty set.
**65. Add an Item to a Set**
```python
{{ set.add(item) }}
```
**Explanation:** Adds an item to a set.
**66. Iterate Over a Set**
```python
...
```
**Explanation:** Iterates over the items in a set.
**67. Check if a Set Contains an Item**
```python
...
```
**Explanation:** Checks if a set contains a specific item.
**68. Intersect Two Sets**
```python
{{ set1.intersection(set2) }}
```
**Explanation:** Creates a new set containing the elements that are common to both sets.
**69. Union Two Sets**
```python
{{ set1.union(set2) }}
```
**Explanation:** Creates a new set containing all the elements from both sets.
**70. Difference Between Two Sets**
```python
{{ 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**
```python
{{ 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**
```python
{{ frozenset() }}
```
**Explanation:** Creates a new frozen set.
**73. Iterate Over a Frozen Set**
```python
...
```
**Explanation:** Iterates over the items in a frozen set.
**74. Check if a Frozen Set Contains an Item**
```python
...
```
**Explanation:** Checks if a frozen set contains a specific item.
**75. Convert a Set to a List**
```python
{{ list(set) }}
```
**Explanation:** Converts a set to a list.
**76. Convert a Tuple to a List**
```python
{{ list(tuple) }}
```
**Explanation:** Converts a tuple to a list.
**77. Convert a Dictionary to a List of Tuples**
```python
{{ 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**
```python
{{ list(dictionary.values()) }}
```
**Explanation:** Converts a dictionary to a list of lists, where each list contains the values for a key in the dictionary.
\*\*79