Support for trimming chars from generated slug's start/end. by mjamro · Pull Request #175 · ctolkien/Slugify

mjamro · 2026-02-13T20:34:43Z

Closes #162

Copilot

Pull request overview

This pull request adds support for trimming specific characters from the start and/or end of generated slugs, addressing issue #162 which requested the ability to remove trailing punctuation like dots from slugs.

Changes:

Added three new configuration options: TrimChars, TrimEndChars, and TrimStartChars to SlugHelperConfiguration
Implemented trimming logic in SlugHelper.GenerateSlug() method
Added comprehensive test coverage for the new trimming functionality
Updated README.md with documentation and examples

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 8 comments.

File	Description
src/Slugify.Core/SlugHelperConfiguration.cs	Added three new char array properties for trimming characters from both ends, end only, or start only
src/Slugify.Core/SlugHelper.cs	Implemented trimming operations in the slug generation pipeline
tests/Slugify.Core.Tests/SlugHelperTests.cs	Added three test methods to validate the trimming functionality
README.md	Added documentation section explaining the new trim options with examples

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Copilot · 2026-02-17T06:18:24Z

src/Slugify.Core/SlugHelper.cs

+        normalizedInput = Config.TrimChars.Length != 0 ? normalizedInput.Trim(Config.TrimChars) : normalizedInput;
+        normalizedInput = Config.TrimEndChars.Length != 0 ? normalizedInput.TrimEnd(Config.TrimEndChars) : normalizedInput;
+        normalizedInput = Config.TrimStartChars.Length != 0 ? normalizedInput.TrimStart(Config.TrimStartChars) : normalizedInput;


The trim operations are applied early in the pipeline, before string replacements and character filtering. This means they cannot trim characters that appear at the edges as a result of transformations. For example, if a string replacement adds a dot at the end, or if character filtering removes characters that expose trailing punctuation, the current implementation won't trim them. The MaximumLength feature (lines 92-100) sets a precedent by trimming trailing dashes AFTER all transformations. Consider moving these trim operations to after line 100 (before the return) to trim from the final slug, which would be more consistent and handle more use cases.

Copilot · 2026-02-17T06:18:24Z

README.md

+Trim options to remove characters from the input before replacements and character filtering. This is useful to prevent generated slug to start/end with certain characters like dot.
+
+- Options
+  - `TrimChars` — characters to trim from both ends (behaves like `string.Trim(char[])`).
+  - `TrimEndChars` — characters to trim from the end (behaves like `string.TrimEnd(char[])`).
+  - `TrimStartChars` — characters to trim from the start (behaves like `string.TrimStart(char[])`).
+
+- Default value: all three are empty arrays (no extra trimming).


The documentation states these options remove characters "from the input before replacements and character filtering", but issue 162 describes wanting to remove trailing punctuation from the generated slug (i.e., the output). The current implementation trims early in the process, which may not match user expectations. Consider updating the documentation to clarify this behavior, or moving the trim operations to apply to the final slug output instead.

Copilot · 2026-02-17T06:18:24Z

tests/Slugify.Core.Tests/SlugHelperTests.cs

+    [Theory]
+    [MemberData(nameof(GenerateStandardSluggers))]
+    public void TestTrimmingEndChars(ISlugHelper helper)
+    {
+        const string original = "hello._world._";
+        const string expected = "hello._world";
+
+        helper.Config = new SlugHelperConfiguration
+        {
+            TrimEndChars = [ '.', '_' ],
+        };
+
+        Assert.Equal(expected, helper.GenerateSlug(original));
+    }


The test only validates trimming characters that exist in the original input. Add a test case where trailing characters appear due to transformations, such as: input "test." with StringReplacements of {".": "-"} and TrimEndChars = ['-']. This would expose whether the trim operations correctly handle characters created during the slug generation process. The current implementation would fail such a test because trimming happens before replacements.

Copilot · 2026-02-17T06:18:24Z

src/Slugify.Core/SlugHelper.cs

        normalizedInput = normalizedInput.Normalize(NormalizationForm.FormD);
        normalizedInput = Config.TrimWhitespace ? normalizedInput.Trim() : normalizedInput;
        normalizedInput = Config.ForceLowerCase ? normalizedInput.ToLowerInvariant() : normalizedInput;
+        normalizedInput = Config.TrimChars.Length != 0 ? normalizedInput.Trim(Config.TrimChars) : normalizedInput;


If a user sets both TrimChars and TrimEndChars (or TrimStartChars), the operations will be applied sequentially, which could lead to unexpected behavior. For example, if TrimChars = ['.'] and TrimEndChars = ['_'], after TrimChars removes dots from both ends, TrimEndChars would then remove underscores. Consider documenting this interaction, or detecting and warning about conflicting configurations, or applying only the most specific option when multiple are set.

Suggested change

normalizedInput = Config.TrimChars.Length != 0 ? normalizedInput.Trim(Config.TrimChars) : normalizedInput;

normalizedInput = Config.TrimChars.Length != 0 && Config.TrimEndChars.Length == 0 && Config.TrimStartChars.Length == 0

? normalizedInput.Trim(Config.TrimChars)

: normalizedInput;

Copilot · 2026-02-17T06:18:24Z

src/Slugify.Core/SlugHelperConfiguration.cs

+    /// List of characters to be trimmed (removed from both ends) from generated slug
+    /// </summary>
+    public char[] TrimChars { get; set; } = [];
+
+    /// <summary>
+    /// List of characters to be trimmed from end of the generated slug
+    /// </summary>
+    public char[] TrimEndChars { get; set; } = [];
+
+    /// <summary>
+    /// List of characters to be trimmed from start of the generated slug


The documentation says "List of characters to be trimmed (removed from both ends) from generated slug" but the trimming happens on the input, not the generated slug. Consider changing to "from the input string" or "before slug generation" for accuracy. Similarly for TrimEndChars and TrimStartChars documentation.

Suggested change

/// List of characters to be trimmed (removed from both ends) from generated slug

/// </summary>

public char[] TrimChars { get; set; } = [];

/// <summary>

/// List of characters to be trimmed from end of the generated slug

/// </summary>

public char[] TrimEndChars { get; set; } = [];

/// <summary>

/// List of characters to be trimmed from start of the generated slug

/// List of characters to be trimmed (removed from both ends) from the input string before slug generation.

/// </summary>

public char[] TrimChars { get; set; } = [];

/// <summary>

/// List of characters to be trimmed from the end of the input string before slug generation.

/// </summary>

public char[] TrimEndChars { get; set; } = [];

/// <summary>

/// List of characters to be trimmed from the start of the input string before slug generation.

src/Slugify.Core/SlugHelperConfiguration.cs

tests/Slugify.Core.Tests/SlugHelperTests.cs

Copilot · 2026-02-17T06:18:25Z

README.md

+
+### `TrimChars`, `TrimEndChars`, `TrimStartChars`
+
+Trim options to remove characters from the input before replacements and character filtering. This is useful to prevent generated slug to start/end with certain characters like dot.


Grammar issue: "to prevent generated slug to start/end" should be either "to prevent the generated slug from starting/ending" or "to prevent generated slugs from starting/ending".

Suggested change

Trim options to remove characters from the input before replacements and character filtering. This is useful to prevent generated slug to start/end with certain characters like dot.

Trim options to remove characters from the input before replacements and character filtering. This is useful to prevent the generated slug from starting or ending with certain characters like dot.

mjamro and others added 2 commits February 13, 2026 21:34

Support for trimming chars from generated slug's start/end.

cd8243f

Merge branch 'main' into main

15cd421

ctolkien requested a review from Copilot February 17, 2026 06:12

Copilot started reviewing on behalf of ctolkien February 17, 2026 06:12 View session

Copilot AI reviewed Feb 17, 2026

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Support for trimming chars from generated slug's start/end.#175

Support for trimming chars from generated slug's start/end.#175
mjamro wants to merge 2 commits intoctolkien:mainfrom
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		### `TrimChars`, `TrimEndChars`, `TrimStartChars`

		Trim options to remove characters from the input before replacements and character filtering. This is useful to prevent generated slug to start/end with certain characters like dot.

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Pull request overview

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