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Caching SVG doesn't cache CSS class name and Viewbox settings #67

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6571a2b
Moved Attr setting to separate method (SVGs)
drpeck Sep 29, 2023
dbb8403
Moved the Attr setting to after cached content (SVGs)
drpeck Sep 29, 2023
c35b0b8
Refactor to cache SVG with attributes separately to SVG content
drpeck Sep 29, 2023
9f24f4a
Update Our.Umbraco.TagHelpers/InlineSvgTagHelper.cs
warrenbuckley Aug 6, 2025
adf5fc0
Update Our.Umbraco.TagHelpers/InlineSvgTagHelper.cs
warrenbuckley Aug 6, 2025
ec6f2ff
Update Our.Umbraco.TagHelpers/InlineSvgTagHelper.cs
warrenbuckley Aug 6, 2025
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106 changes: 79 additions & 27 deletions Our.Umbraco.TagHelpers/InlineSvgTagHelper.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -85,6 +85,31 @@ public InlineSvgTagHelper(MediaFileManager mediaFileManager, IWebHostEnvironment
[HtmlAttributeName("ignore-appsettings")]
public bool IgnoreAppSettings { get; set; }



private string CalculateSvgContentCacheKey() {
if (MediaItem is not null)
{
return string.Concat("MediaItem-SvgContents (", MediaItem.Key.ToString(), ")");
}

if (string.IsNullOrWhiteSpace(FileSource) == false)
{
return string.Concat("File-SvgContents (", FileSource, ")");
}

return string.Empty;
}

private string CalculateSetAttrsCacheKey (string cleanedFileContents)
=> $"SvgWithAttributes ({CssClass?.GetHashCode()}_{cleanedFileContents.GetHashCode()})";

Comment on lines +105 to +106
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Copilot AI Aug 6, 2025

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Using GetHashCode() for cache keys can cause collisions since GetHashCode() is not guaranteed to be unique or consistent across application restarts. Consider using a more deterministic approach like combining the actual values or using a cryptographic hash.

Suggested change
=> $"SvgWithAttributes ({CssClass?.GetHashCode()}_{cleanedFileContents.GetHashCode()})";
{
// Use actual values or a deterministic hash for the cache key
var cssClassValue = CssClass ?? string.Empty;
var combined = cssClassValue + "|" + cleanedFileContents;
var hash = ComputeSHA256Hash(combined);
return $"SvgWithAttributes ({hash})";
}
private static string ComputeSHA256Hash(string input)
{
using (var sha256 = SHA256.Create())
{
var bytes = Encoding.UTF8.GetBytes(input);
var hashBytes = sha256.ComputeHash(bytes);
var sb = new StringBuilder();
foreach (var b in hashBytes)
{
sb.Append(b.ToString("x2"));
}
return sb.ToString();
}
}

Copilot uses AI. Check for mistakes.

private int FetchCacheMinutes()
=> CacheMinutes > 0 ? CacheMinutes : _globalSettings.OurSVG.CacheMinutes;

private bool FetchEnsureViewBoxStatus () =>
EnsureViewBox || (_globalSettings.OurSVG.EnsureViewBox && !IgnoreAppSettings);

public override void Process(TagHelperContext context, TagHelperOutput output)
{
// Can only use media-item OR src
Expand All @@ -99,23 +124,14 @@ public override void Process(TagHelperContext context, TagHelperOutput output)
}

string? cleanedFileContents = null;

if(Cache || (_globalSettings.OurSVG.Cache && !IgnoreAppSettings))
var doCache = Cache || (_globalSettings.OurSVG.Cache && !IgnoreAppSettings);
if (doCache)
{
var cacheName = string.Empty;
var cacheMins = CacheMinutes > 0 ? CacheMinutes : _globalSettings.OurSVG.CacheMinutes;

if (MediaItem is not null)
{
cacheName = string.Concat("MediaItem-SvgContents (", MediaItem.Key.ToString(), ")");
}
else if (string.IsNullOrWhiteSpace(FileSource) == false)
{
cacheName = string.Concat("File-SvgContents (", FileSource, ")");
}
var cacheKey = CalculateSvgContentCacheKey();
var cacheMins = FetchCacheMinutes();

cleanedFileContents = _appCaches.RuntimeCache.GetCacheItem(cacheName, () =>
{
cleanedFileContents = _appCaches.RuntimeCache.GetCacheItem(cacheKey, () =>
{
return GetFileContents();
}, TimeSpan.FromMinutes(cacheMins));
}
Expand All @@ -130,12 +146,28 @@ public override void Process(TagHelperContext context, TagHelperOutput output)
return;
}

string svgWithAttributes;
if (doCache)
{
var cacheKey = CalculateSetAttrsCacheKey(cleanedFileContents);
var cacheMins = FetchCacheMinutes();

svgWithAttributes = _appCaches.RuntimeCache.GetCacheItem(cacheKey, () =>
{
return ParseAndSetAttrs(cleanedFileContents);
}, TimeSpan.FromMinutes(cacheMins));
}
else
{
svgWithAttributes = ParseAndSetAttrs(cleanedFileContents);
}

// Remove the src attribute or media-item from the <svg>
output.Attributes.RemoveAll("src");
output.Attributes.RemoveAll("media-item");

output.TagName = null; // Remove <our-svg>
output.Content.SetHtmlContent(cleanedFileContents);
output.Content.SetHtmlContent(svgWithAttributes);
}

private string? GetFileContents()
Expand Down Expand Up @@ -201,18 +233,38 @@ public override void Process(TagHelperContext context, TagHelperOutput output)
@"syntax:error:",
RegexOptions.IgnoreCase | RegexOptions.Singleline);

if ((EnsureViewBox || (_globalSettings.OurSVG.EnsureViewBox && !IgnoreAppSettings)) || !string.IsNullOrEmpty(CssClass))
return cleanedFileContents;
}

/// <summary>
/// Set CSS Class, Viewbox, and/or width/height
/// </summary>
/// <param name="cleanedFileContents">SVG file contents</param>
/// <returns>SVG file contents with attributes</returns>
private string ParseAndSetAttrs(string cleanedFileContents) {
var doEnsureViewBox = FetchEnsureViewBoxStatus();
var hasCssClass = !string.IsNullOrEmpty(CssClass);

// No work to do (save the unnecessary LoadHtml)
if (!doEnsureViewBox && !hasCssClass)
{
return cleanedFileContents;
}

HtmlDocument doc = new HtmlDocument();
doc.LoadHtml(cleanedFileContents);
var svgs = doc.DocumentNode.SelectNodes("//svg");
foreach (var svgNode in svgs)
{
HtmlDocument doc = new HtmlDocument();
doc.LoadHtml(cleanedFileContents);
var svgs = doc.DocumentNode.SelectNodes("//svg");
foreach (var svgNode in svgs)
if (hasCssClass)
{
if (!string.IsNullOrEmpty(CssClass))
{
svgNode.AddClass(CssClass);
}
if ((EnsureViewBox || (_globalSettings.OurSVG.EnsureViewBox && !IgnoreAppSettings)) && svgNode.Attributes.Contains("width") && svgNode.Attributes.Contains("height") && !svgNode.Attributes.Contains("viewbox"))
svgNode.AddClass(CssClass);
}

if (doEnsureViewBox)
{
var hasDimensionsAndNoViewbox = svgNode.Attributes.Contains("width") && svgNode.Attributes.Contains("height") && !svgNode.Attributes.Contains("viewbox");
if (hasDimensionsAndNoViewbox)
{
var width = StringUtils.GetDecimal(svgNode.GetAttributeValue("width", "0"));
var height = StringUtils.GetDecimal(svgNode.GetAttributeValue("height", "0"));
Expand All @@ -222,8 +274,8 @@ public override void Process(TagHelperContext context, TagHelperOutput output)
svgNode.Attributes.Remove("height");
}
}
cleanedFileContents = doc.DocumentNode.OuterHtml;
}
cleanedFileContents = doc.DocumentNode.OuterHtml;

return cleanedFileContents;
}
Expand Down