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Overview

The LogEvent class represents a single log event in Serilog. It encapsulates all information about a logging occurrence, including the timestamp, severity level, message template, properties, exception details, and distributed tracing identifiers.

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Constructors

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LogEvent(DateTimeOffset, LogEventLevel, Exception, MessageTemplate, IEnumerable<LogEventProperty>)

Construct a new log event.
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timestamp
DateTimeOffset
required
The time at which the event occurred.
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level
LogEventLevel
required
The level of the event.
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exception
Exception
An exception associated with the event, or null.
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messageTemplate
MessageTemplate
required
The message template describing the event.
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properties
IEnumerable<LogEventProperty>
required
Properties associated with the event, including those presented in the message template.
Exceptions:
  • ArgumentNullException - When messageTemplate or properties is null

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LogEvent(DateTimeOffset, LogEventLevel, Exception, MessageTemplate, IEnumerable<LogEventProperty>, ActivityTraceId, ActivitySpanId)

Construct a new log event with distributed tracing identifiers.
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timestamp
DateTimeOffset
required
The time at which the event occurred.
​
level
LogEventLevel
required
The level of the event.
​
exception
Exception
An exception associated with the event, or null.
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messageTemplate
MessageTemplate
required
The message template describing the event.
​
properties
IEnumerable<LogEventProperty>
required
Properties associated with the event, including those presented in the message template.
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traceId
ActivityTraceId
required
The id of the trace that was active when the event was created, if any.
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spanId
ActivitySpanId
required
The id of the span that was active when the event was created, if any.
Exceptions:
  • ArgumentNullException - When messageTemplate or properties is null

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Properties

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Timestamp
DateTimeOffset
The time at which the event occurred.
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Level
LogEventLevel
The level of the event.
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TraceId
ActivityTraceId?
The id of the trace that was active when the event was created, if any. Returns null if no trace was active.
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SpanId
ActivitySpanId?
The id of the span that was active when the event was created, if any. Returns null if no span was active.
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MessageTemplate
MessageTemplate
The message template describing the event.
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Properties
IReadOnlyDictionary<string, LogEventPropertyValue>
Properties associated with the event, including those presented in the message template.
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Exception
Exception
An exception associated with the event, or null.

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Methods

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RenderMessage(TextWriter, IFormatProvider)

Render the message template to the specified output, given the properties associated with the event.
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output
TextWriter
required
The output writer to render the message to.
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formatProvider
IFormatProvider
Supplies culture-specific formatting information, or null.
var writer = new StringWriter();
logEvent.RenderMessage(writer);
string message = writer.ToString();

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RenderMessage(IFormatProvider)

Render the message template given the properties associated with the event, and return the result.
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formatProvider
IFormatProvider
Supplies culture-specific formatting information, or null.
Returns: string - The rendered message 
string message = logEvent.RenderMessage();

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AddOrUpdateProperty(LogEventProperty)

Add a property to the event if not already present, otherwise, update its value.
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property
LogEventProperty
required
The property to add or update.
Exceptions:
  • ArgumentNullException - When property is null
var property = new LogEventProperty("UserId", new ScalarValue(123));
logEvent.AddOrUpdateProperty(property);

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AddPropertyIfAbsent(LogEventProperty)

Add a property to the event if not already present.
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property
LogEventProperty
required
The property to add.
Exceptions:
  • ArgumentNullException - When property is null
var property = new LogEventProperty("RequestId", new ScalarValue("abc123"));
logEvent.AddPropertyIfAbsent(property);

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AddPropertyIfAbsent(ILogEventPropertyFactory, string, object, bool)

Add a property to the event if not already present using a factory.
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factory
ILogEventPropertyFactory
required
Factory for creating the property to add to the event.
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name
string
required
The name of the property.
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value
object
The value of the property.
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destructureObjects
bool
default:"false"
If true, and the value is a non-primitive, non-array type, then the value will be converted to a structure; otherwise, unknown types will be converted to scalars.
Exceptions:
  • ArgumentNullException - When factory is null
logEvent.AddPropertyIfAbsent(logger, "Context", contextObject, destructureObjects: true);

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RemovePropertyIfPresent(string)

Remove a property from the event, if present. Otherwise no action is performed.
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propertyName
string
required
The name of the property to remove.
logEvent.RemovePropertyIfPresent("SensitiveData");

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Static Methods

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UnstableAssembleFromParts

Construct a LogEvent using pre-allocated values for internal fields. This method allows specialized callers to avoid dictionary allocation overhead.
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timestamp
DateTimeOffset
required
The time at which the event occurred.
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level
LogEventLevel
required
The level of the event.
​
exception
Exception
An exception associated with the event, or null.
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messageTemplate
MessageTemplate
required
The message template describing the event.
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properties
Dictionary<string, LogEventPropertyValue>
required
Properties associated with the event, including those presented in the message template.
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traceId
ActivityTraceId
required
The id of the trace that was active when the event was created, if any.
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spanId
ActivitySpanId
required
The id of the span that was active when the event was created, if any.
Returns: LogEvent - A constructed log event Exceptions:
  • ArgumentNullException - When messageTemplate or properties is null
Because this method exposes parameters that map 1:1 with internal fields of LogEvent, the parameter list may change across major Serilog versions.
var properties = new Dictionary<string, LogEventPropertyValue>();
var logEvent = LogEvent.UnstableAssembleFromParts(
    DateTimeOffset.Now,
    LogEventLevel.Information,
    null,
    messageTemplate,
    properties,
    default,
    default
);

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