Additional report tags (#11718)

* Add some more convenience functions for report helpers

* Add "reverse" tag

* Add unit tests

* Add lstrip and rstrip

* Fix unit tests

docs/docs/report/helpers.md

@@ -173,8 +173,144 @@ Generate a list of all active customers:
 
 More advanced database filtering should be achieved using a [report plugin](../plugins/mixins/report.md), and adding custom context data to the report template.
 
+## List Helpers
+
+The following helper functions are available for working with list (or list-like) data structures:
+
+### length
+
+Return the length of a list (or list-like) data structure. Note that this will also work for other data structures which support the `len()` function, such as strings, dictionaries or querysets:
+
+::: report.templatetags.report.length
+    options:
+        show_docstring_description: false
+        show_source: False
+
+### first
+
+Return the first element of a list (or list-like) data structure:
+
+::: report.templatetags.report.first
+    options:
+        show_docstring_description: false
+        show_source: False
+
+
+### last
+
+Return the last element of a list (or list-like) data structure:
+
+::: report.templatetags.report.last
+    options:
+        show_docstring_description: false
+        show_source: False
+
+### reverse
+
+Return a list (or list-like) data structure in reverse order:
+
+::: report.templatetags.report.reverse
+    options:
+        show_docstring_description: false
+        show_source: False
+
+### truncate
+
+Return a truncated version of a list (or list-like) data structure, containing only the first N elements:
+
+::: report.templatetags.report.truncate
+    options:
+        show_docstring_description: false
+        show_source: False
+
+## String Formatting
+
+### strip
+
+Return a string with leading and trailing whitespace removed:
+
+::: report.templatetags.report.strip
+    options:
+        show_docstring_description: false
+        show_source: False
+
+
+### lstrip
+
+Return a string with leading whitespace removed:
+
+::: report.templatetags.report.lstrip
+    options:
+        show_docstring_description: false
+        show_source: False
+
+### rstrip
+
+Return a string with trailing whitespace removed:
+
+::: report.templatetags.report.rstrip
+    options:
+        show_docstring_description: false
+        show_source: False
+
+### split
+
+Return a list of substrings by splitting a string based on a specified separator:
+
+::: report.templatetags.report.split
+    options:
+        show_docstring_description: false
+        show_source: False
+
+### join
+
+Return a string by joining a list of strings into a single string, using a specified separator:
+
+::: report.templatetags.report.join
+    options:
+        show_docstring_description: false
+        show_source: False
+
+### replace
+
+Return a string where occurrences of a specified substring are replaced with another substring:
+
+::: report.templatetags.report.replace
+    options:
+        show_docstring_description: false
+        show_source: False
+
+### lowercase
+
+Return a string with all characters converted to lowercase:
+
+::: report.templatetags.report.lowercase
+    options:
+        show_docstring_description: false
+        show_source: False
+
+### uppercase
+
+Return a string with all characters converted to uppercase:
+
+::: report.templatetags.report.uppercase
+    options:
+        show_docstring_description: false
+        show_source: False
+
+### titlecase
+
+Return a string with the first character of each word converted to uppercase and the remaining characters converted to lowercase:
+
+::: report.templatetags.report.titlecase
+    options:
+        show_docstring_description: false
+        show_source: False
+
 ## Number Formatting
 
+A number of helper functions are available for formatting numbers in a particular way. These can be used to format numbers according to a particular number of decimal places, or to add leading zeros, for example.
+
 ### format_number
 
 The helper function `format_number` allows for some common number formatting options. It takes a number (or a number-like string) as an input, as well as some formatting arguments. It returns a *string* containing the formatted number:

src/backend/InvenTree/report/templatetags/report.py

@@ -1036,3 +1036,196 @@ def include_icon_fonts(ttf: bool = False, woff: bool = False):
     """
 
     return mark_safe(icon_class + '\n'.join(fonts))
+
+
+@register.simple_tag()
+def lowercase(value: str) -> str:
+    """Convert a string to lowercase.
+
+    Arguments:
+        value: The string to be converted
+    """
+    if not value:
+        return ''
+    return str(value).lower()
+
+
+@register.simple_tag()
+def uppercase(value: str) -> str:
+    """Convert a string to uppercase.
+
+    Arguments:
+        value: The string to be converted
+    """
+    if not value:
+        return ''
+    return str(value).upper()
+
+
+@register.simple_tag()
+def titlecase(value: str) -> str:
+    """Convert a string to title case.
+
+    Arguments:
+        value: The string to be converted
+    """
+    if not value:
+        return ''
+    return str(value).title()
+
+
+@register.simple_tag()
+def strip(value: str, chars: Optional[str] = ' ') -> str:
+    """Strip leading and trailing characters from a string.
+
+    Arguments:
+        value: The string to be stripped
+        chars: The set of characters to strip from the string (default = whitespace)
+    """
+    if not value:
+        return ''
+    return str(value).strip(chars)
+
+
+@register.simple_tag()
+def lstrip(value: str, chars: Optional[str] = ' ') -> str:
+    """Strip leading characters from a string.
+
+    Arguments:
+        value: The string to be stripped
+        chars: The set of characters to strip from the string (default = whitespace)
+    """
+    if not value:
+        return ''
+    return str(value).lstrip(chars)
+
+
+@register.simple_tag()
+def rstrip(value: str, chars: Optional[str] = ' ') -> str:
+    """Strip trailing characters from a string.
+
+    Arguments:
+        value: The string to be stripped
+        chars: The set of characters to strip from the string (default = whitespace)
+    """
+    if not value:
+        return ''
+    return str(value).rstrip(chars)
+
+
+@register.simple_tag()
+def split(value: str, separator: str = ',') -> list:
+    """Split a string into a list, using the provided separator (default = ',').
+
+    Arguments:
+        value: The string to be split
+        separator: The character to use as a separator (default = ',')
+    """
+    if not value:
+        return []
+    return [v.strip() for v in str(value).split(separator)]
+
+
+@register.simple_tag()
+def join(value: list, separator: str = ',') -> str:
+    """Join a list of items into a string, using the provided separator (default = ',').
+
+    Arguments:
+        value: The list of items to be joined
+        separator: The character to use as a separator (default = ',')
+    """
+    if not value:
+        return ''
+    return separator.join(str(v) for v in value)
+
+
+@register.simple_tag()
+def length(value: Any) -> int:
+    """Return the length of a list or string.
+
+    Arguments:
+        value: The value to be measured (e.g. a list or string)
+    """
+    if value is None:
+        return 0
+    try:
+        return len(value)
+    except TypeError:
+        return 0
+
+
+@register.simple_tag()
+def replace(value: str, old: str, new: str = '') -> str:
+    """Replace occurrences of a substring within a string with a new value.
+
+    Arguments:
+        value: The original string
+        old: The substring to be replaced
+        new: The value to replace the old substring with (default = "")
+    """
+    if not value:
+        return ''
+    return str(value).replace(old, new)
+
+
+@register.simple_tag()
+def first(value: list, default: Any = None) -> Any:
+    """Return the first item in a list, or a default value if the list is empty.
+
+    Arguments:
+        value: The list from which to retrieve the first item
+        default: The value to return if the list is empty (default = None)
+    """
+    if not value:
+        return default
+    try:
+        return value[0]
+    except (IndexError, TypeError):
+        return default
+
+
+@register.simple_tag()
+def last(value: list, default: Any = None) -> Any:
+    """Return the last item in a list, or a default value if the list is empty.
+
+    Arguments:
+        value: The list from which to retrieve the last item
+        default: The value to return if the list is empty (default = None)
+    """
+    if not value:
+        return default
+    try:
+        return value[-1]
+    except (IndexError, TypeError):
+        return default
+
+
+@register.simple_tag()
+def reverse(value: list) -> list:
+    """Return a reversed version of the provided list.
+
+    Arguments:
+        value: The list to be reversed
+    """
+    if not value:
+        return []
+    try:
+        return value[::-1]
+    except TypeError:
+        return []
+
+
+@register.simple_tag()
+def truncate(value: list, length: int) -> list:
+    """Return a truncated version of the provided list.
+
+    Arguments:
+        value: The list to be truncated
+        length: The maximum length of the returned list
+    """
+    if not value:
+        return []
+    try:
+        return value[:length]
+    except TypeError:
+        return []

src/backend/InvenTree/report/test_tags.py

@@ -231,6 +231,47 @@ class ReportTagTest(PartImageTestMixin, InvenTreeTestCase):
             logo = report_tags.logo_image()
             self.assertIn('inventree.png', logo)
 
+    def test_string_tags(self):
+        """Simple tests for the string manipulation tags."""
+        self.assertEqual(report_tags.uppercase('hello world'), 'HELLO WORLD')
+        self.assertEqual(report_tags.lowercase('HELLO WORLD'), 'hello world')
+        self.assertEqual(report_tags.titlecase('hello world'), 'Hello World')
+
+        self.assertEqual(report_tags.strip('  hello world  '), 'hello world')  # noqa: B005
+        self.assertEqual(report_tags.strip('  hello world  ', chars=' hd'), 'ello worl')  # noqa: B005
+        self.assertEqual(report_tags.strip('xxhelloxx', chars='xy'), 'hello')  # noqa: B005
+
+        self.assertEqual(report_tags.lstrip('  hello world  '), 'hello world  ')  # noqa: B005
+        self.assertEqual(report_tags.rstrip('  world  ', chars=' dl'), '  wor')  # noqa: B005
+
+        self.assertEqual(report_tags.split('a,b,c', separator=','), ['a', 'b', 'c'])
+        self.assertEqual(report_tags.split('a,|,b|c', separator='|'), ['a,', ',b', 'c'])
+
+        self.assertEqual(report_tags.join(['a', 'b', 'c'], separator=','), 'a,b,c')
+        self.assertEqual(report_tags.join(['a', 'b', 'c'], separator='|'), 'a|b|c')
+        self.assertEqual(report_tags.join(None, separator=','), '')
+
+        self.assertEqual(report_tags.replace('hello world', 'world'), 'hello ')
+        self.assertEqual(
+            report_tags.replace('hello world', 'world', 'there'), 'hello there'
+        )
+
+        self.assertEqual(report_tags.first('hello world'), 'h')
+        self.assertEqual(report_tags.last('hello world'), 'd')
+        self.assertEqual(report_tags.length('hello world'), 11)
+        self.assertEqual(report_tags.truncate('hello world', length=3), 'hel')
+        self.assertEqual(report_tags.reverse('hello world'), 'dlrow olleh')
+
+    def test_list_tags(self):
+        """Simple tests for list manipulation tags."""
+        self.assertEqual(report_tags.first([1, 2, 3]), 1)
+        self.assertEqual(report_tags.last([1, 2, 3]), 3)
+        self.assertEqual(report_tags.length([1, 2, 3]), 3)
+        self.assertEqual(report_tags.reverse([1, 2, 3]), [3, 2, 1])
+        self.assertEqual(report_tags.truncate([1, 2, 3], 2), [1, 2])
+        self.assertEqual(report_tags.join([1, 2, 3], separator=','), '1,2,3')
+        self.assertEqual(report_tags.join(None, separator=','), '')
+
     def test_maths_tags(self):
         """Simple tests for mathematical operator tags."""
         self.assertEqual(report_tags.add(1, 2), 3)