Log Reader Service

Overview

ILogReaderService reads the log files the application has written to disk and streams them back as LogMessage items. The default LogReaderService enumerates the *.logs files in the configured folder and deserializes the JSON entries they contain.

These files are produced by the file logging provider (RegisterLogToFile), which writes structured JSON entries into rolling yyyy-MM-dd_N.logs files. The reader is the other half of that pair: it reads from the same folder and expects the same format. The built-in Log Viewer page uses this service as its data source.

The order of the returned messages is not guaranteed — sort them on the consuming side if you need a strict chronology.

Usage

Enumerate the messages with await foreach; pass a CancellationToken to stop a long enumeration early:

await foreach (var message in logReaderService.LoadItemsFromLogFile(cancel))
{
    // handle the entry
}

Registration

The service is part of the core services and by default reads from the standard log folder:

services.RegisterLogViewer();

The folder is taken from the LogViewer configuration section (LogReaderOptions) and resolved relative to the application data folder; it defaults to logs. To override it in code, pass a configure delegate:

services.RegisterLogViewer(b => b.WithFolder("mylogs"));

In a design-time environment the registration is skipped entirely; DesignTime.LogReaderService provides NullLogReaderService.Instance, which returns no messages.

API

ILogReaderService

Reads saved log files and streams their entries.

Method	Return Type	Description
`LoadItemsFromLogFile(cancel)`	`IAsyncEnumerable<LogMessage>`	Reads all `*.logs` files from the configured folder and streams the parsed entries.

`ILogReaderService.LoadItemsFromLogFile`

Parameter	Type	Description
`cancel`	`CancellationToken`	A token that cancels the enumeration.

LogMessage

Represents a single log entry.

Property	Type	Description
`Timestamp`	`DateTime`	Time the entry was written.
`LogLevel`	`LogLevel`	Severity level.
`Category`	`string`	Logger category the entry belongs to.
`Message`	`string`	Log message text.
`Description`	`string?`	Optional additional details.

Last modified: 24 July 2026