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Fix SnakeCase conversion for properties with consecutive uppercase letters #839

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Merged
sebastienros merged 2 commits into from
Oct 23, 2025
Merged

Fix SnakeCase conversion for properties with consecutive uppercase letters #839

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Copilot Oct 23, 2025
8dda966
Fix SnakeCase conversion for consecutive uppercase letters
Copilot Oct 23, 2025
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42 changes: 42 additions & 0 deletions Fluid.Tests/TemplateTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1143,6 +1143,48 @@ public void MemberNameStrategiesHandleSuccessiveUppercase()
Assert.Equal("uv_index", snakeCase);
}

[Fact]
public void SnakeCaseHandlesAcronymsCorrectly()
{
// Test UserName -> user_name
Assert.Equal("user_name", MemberNameStrategies.SnakeCase(typeof(TestClass_UserName).GetProperty("UserName")));

// Test OpenAIModel -> open_ai_model
Assert.Equal("open_ai_model", MemberNameStrategies.SnakeCase(typeof(TestClass_OpenAIModel).GetProperty("OpenAIModel")));

// Test OEMVendor -> oem_vendor
Assert.Equal("oem_vendor", MemberNameStrategies.SnakeCase(typeof(TestClass_OEMVendor).GetProperty("OEMVendor")));

// Test IDSecurity -> id_security
Assert.Equal("id_security", MemberNameStrategies.SnakeCase(typeof(TestClass_IDSecurity).GetProperty("IDSecurity")));

// Test ID -> id
Assert.Equal("id", MemberNameStrategies.SnakeCase(typeof(TestClass_ID).GetProperty("ID")));

// Test XMLParser -> xml_parser
Assert.Equal("xml_parser", MemberNameStrategies.SnakeCase(typeof(TestClass_XMLParser).GetProperty("XMLParser")));

// Test HTMLElement -> html_element
Assert.Equal("html_element", MemberNameStrategies.SnakeCase(typeof(TestClass_HTMLElement).GetProperty("HTMLElement")));

// Test IOError -> io_error
Assert.Equal("io_error", MemberNameStrategies.SnakeCase(typeof(TestClass_IOError).GetProperty("IOError")));

// Test JSONData -> json_data
Assert.Equal("json_data", MemberNameStrategies.SnakeCase(typeof(TestClass_JSONData).GetProperty("JSONData")));
}

private class TestClass_UserName { public string UserName { get; set; } }
private class TestClass_OpenAIModel { public string OpenAIModel { get; set; } }
private class TestClass_OEMVendor { public string OEMVendor { get; set; } }
private class TestClass_IDSecurity { public string IDSecurity { get; set; } }
private class TestClass_ID { public int ID { get; set; } }
private class TestClass_UVIndex { public string UVIndex { get; set; } }
private class TestClass_XMLParser { public string XMLParser { get; set; } }
private class TestClass_HTMLElement { public string HTMLElement { get; set; } }
private class TestClass_IOError { public string IOError { get; set; } }
private class TestClass_JSONData { public string JSONData { get; set; } }

[Fact]
public async Task ShouldIterateOnDictionaries()
{
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56 changes: 34 additions & 22 deletions Fluid/MemberNameStrategies.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -45,26 +45,43 @@ public static string RenameCamelCase(MemberInfo member)

public static string RenameSnakeCase(MemberInfo member)
{
var upper = 0;
for (var i = 1; i < member.Name.Length; i++)
// Calculate the exact number of underscores needed
var underscores = 0;
var previousUpper = false;

for (var i = 0; i < member.Name.Length; i++)
{
if (char.IsUpper(member.Name[i]))
var c = member.Name[i];
if (char.IsUpper(c))
{
if (i > 0 && (!previousUpper || (i + 1 < member.Name.Length && char.IsLower(member.Name[i + 1]))))
{
underscores++;
}
previousUpper = true;
}
else
{
upper++;
previousUpper = false;
}
}

return String.Create(member.Name.Length + upper, member.Name, (data, name) =>
return String.Create(member.Name.Length + underscores, member.Name, (data, name) =>
{
var previousUpper = false;
previousUpper = false;
var k = 0;

for (var i = 0; i < name.Length; i++)
{
var c = name[i];
if (char.IsUpper(c))
{
if (i > 0 && !previousUpper)
// Insert underscore if:
// 1. Not at the start (i > 0)
// 2. Either:
// a. Previous char was not uppercase (transition from lowercase to uppercase)
// b. Previous char was uppercase AND next char is lowercase (end of acronym, start of new word)
if (i > 0 && (!previousUpper || (i + 1 < name.Length && char.IsLower(name[i + 1]))))
{
data[k++] = '_';
}
Expand Down Expand Up @@ -103,36 +120,31 @@ public static string RenameSnakeCase(MemberInfo member)
return string.Empty;

StringBuilder result = new StringBuilder();
bool wasPrevUpper = false; // Track if the previous character was uppercase
int uppercaseCount = 0; // Count consecutive uppercase letters at the start
bool previousUpper = false;

for (int i = 0; i < input.Length; i++)
{
char c = input[i];

if (char.IsUpper(c))
{
if (i > 0 && (!wasPrevUpper || (uppercaseCount > 1 && i < input.Length - 1 && char.IsLower(input[i + 1]))))
// Insert underscore if:
// 1. Not at the start (i > 0)
// 2. Either:
// a. Previous char was not uppercase (transition from lowercase to uppercase)
// b. Previous char was uppercase AND next char is lowercase (end of acronym, start of new word)
if (i > 0 && (!previousUpper || (i + 1 < input.Length && char.IsLower(input[i + 1]))))
{
result.Append('_');
}

result.Append(char.ToLower(c));
wasPrevUpper = true;
uppercaseCount++;
previousUpper = true;
}
else
{
if (c == ' ' || c == '-')
{
result.Append('_'); // Replace spaces and hyphens with underscores
}
else
{
result.Append(c);
}

wasPrevUpper = false;
result.Append(c);
previousUpper = false;
}
}

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