C# Razor Tag Helper Support

C# Razor Tag Helper Support is a Visual Studio Code extension that extends the official C# extension with additional support for custom Razor Tag Helpers in Razor views (.cshtml / .razor).

The extension scans C# projects to detect Tag Helper classes and provides improved editor assistance when working with them.

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Features

Automatic Tag Helper Discovery

• Scans .cs files in the current workspace
• Detects classes that implement Razor Tag Helpers
• Resolves tag names from HtmlTargetElement attributes
• Extracts public properties to determine available attributes

Tag Name IntelliSense

• Provides suggestions for detected Tag Helpers while typing HTML tags in Razor views
• Integrates with the IntelliSense provided by the official C# extension

Attribute IntelliSense

• Suggests attributes that belong to the detected Tag Helper
• Filters attribute suggestions based on the current tag
• Inserts attributes using snippets with the cursor positioned inside quotes

Hover Documentation

• Displays documentation for Tag Helpers and their attributes
• Uses XML documentation comments (/// <summary>) from the C# source code
• Shows helpful tooltips directly in Razor files

Tag Helper Folding

• Adds fold markers for discovered Tag Helper elements in .cshtml / .razor files
• Collapses multi-line opening tags (typical for a <grid> whose select attribute holds a large SQL string)
• Collapses matching open/close Tag Helper pairs, including nesting
• Ignores markup that appears inside C# verbatim strings, quoted attributes, and comments
• Command C# Razor Tag Helper Support: Fold All Tag Helpers folds every Tag Helper in the current file
• Multi-line attributes (especially select / lookup-sql with SQL) get their own fold, so the query can be collapsed without hiding the rest of the tag
• Can be turned off with csharpRazorTagHelpers.enableFolding

Select Attribute Value

• Command C# Razor Tag Helper Support: Select Attribute Value selects only the inner value of the attribute under the cursor (the SQL inside select="@(@" ... ")", not the whole <grid>)
• Also available from the editor context menu (right-click) in .cshtml / .razor files
• If the cursor is on the tag name or between attributes, the select attribute is used when present
• Expand Selection (Shift+Alt+Right / Alt+Shift+Right) grows from the SQL, to the whole attribute, to the whole Tag Helper

Go to Definition (F12)

• F12 on a Tag Helper element name (<grid>, </filters>) jumps to the C# Tag Helper class
• F12 on an attribute name jumps to the corresponding C# property (including properties inherited from a base Tag Helper)

SQL highlighting

• Highlights SQL keywords, comments, strings, and numbers inside configured Tag Helper attributes (default: select, insert, update, delete, move, lookup-sql, sql on any tag)

• Restrict or extend via csharpRazorTagHelpers.sqlHighlighting.rules, for example only <grid> and <filter>:

  "csharpRazorTagHelpers.sqlHighlighting.rules": [
    { "tag": "grid", "attributes": ["select", "insert", "update", "delete"] },
    { "tag": "filter", "attributes": ["lookup-sql"] }
  ]
  

• tag can be a helper name or * (any element). attributes can include * (every attribute of that tag)

• Turn off with csharpRazorTagHelpers.sqlHighlighting.enabled

Outline

• Tag Helpers appear in Outline / breadcrumbs as nested symbols (grid#grid-talent-matrix, filter[programId])

Copy Attribute Value

• Command Copy Attribute Value (also in the editor context menu) copies the inner value (e.g. SQL in select) to the clipboard

Diagnostics

• Warns about unknown attributes on a known Tag Helper (typos like hide-item-buton-p); HTML, data-*, aria-*, and asp-* are ignored
• Warns when a helper is used outside its ParentTag (e.g. <filter> outside <filters-group>)
• Toggle with csharpRazorTagHelpers.diagnostics.enabled

What's New

• After a fresh install or an update, a What's New tab opens with the same CHANGELOG.md as on GitHub (markdown, not a webview)
• Reopen anytime: C# Razor Tag Helper Support: What's New
• Turn off auto-open with csharpRazorTagHelpers.showWhatsNewOnUpdate

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How It Works

1. The extension scans the workspace for .cs files.
2. Tag Helper classes are detected automatically.
3. Tag names and attributes are extracted from the C# code.
4. IntelliSense suggestions are provided inside Razor views.

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Supported Files

• .cshtml
• .razor
• .cs (for Tag Helper detection)

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Requirements

• Visual Studio Code

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License

MIT