TagAttribute

TagAttribute

Important

v4 Update: All attributes are now in the unified Purview.Telemetry namespace.

The TagAttribute is used within Activity and Metric generation to specify how parameters are added as tags.

In v4, tag names follow the configured NamingConvention:

• OpenTelemetry (default): Uses snake_case for compound words (e.g., "entity_id")
• Legacy: Uses lowercase smashed format (e.g., "entityid")

TagAttribute Properties

Name	Type	Default	Description
Name	string?	null	Explicitly sets the name of the tag. When null, the parameter name is used (and transformed according to NamingConvention).
SkipOnNullOrEmpty	bool	false	When true, the tag is not added if the parameter value is null or default.

Usage Examples

using Purview.Telemetry;

[ActivitySource("OrderService")]
interface IOrderTelemetry
{
    [Activity]
    Activity? ProcessingOrder(
        // Auto-named tag (becomes "order_id" in OpenTelemetry mode)
        [Tag]int orderId,
        
        // Explicitly named tag
        [Tag(Name = "customer.name")]string customerName,
        
        // Skip if null
        [Tag(SkipOnNullOrEmpty = true)]string? notes
    );
}

Tag Naming in v4

The tag name generation depends on the NamingConvention setting:

OpenTelemetry Convention (default):

[Tag]int orderId       // Generated: "order_id"
[Tag]string userName   // Generated: "user_name"
[Tag(Name = "my.custom.tag")]int value  // Generated: "my.custom.tag" (explicit names not transformed)

Legacy Convention:

[Tag]int orderId       // Generated: "orderid"
[Tag]string userName   // Generated: "username"

To change the convention, see Generation - Naming Conventions.

Best Practices

1. Use explicit names for cross-service tags - Prevents issues if parameter names change:

   [Tag(Name = "trace.id")]string traceId

2. Use SkipOnNullOrEmpty for optional tags - Avoids cluttering telemetry with null values:

   [Tag(SkipOnNullOrEmpty = true)]string? optionalContext

3. Follow OpenTelemetry semantic conventions - Use standard names like http.method, http.status_code, service.name:

   [Tag(Name = "http.method")]string method
   [Tag(Name = "http.status_code")]int statusCode

4. Compound words: Let v4's OpenTelemetry mode handle it automatically:

   // Good - auto-transforms to "customer_id"
   [Tag]int customerId
   
   // Also good - explicit naming
   [Tag(Name = "customer.id")]int id

See Also

• Activities - Using tags in activities
• Metrics - Using tags in metrics
• Generation - Naming convention configuration
• Breaking Changes - v3 to v4 naming changes