@agileforge/ngx-wlog
v18.0.6
Published
Angular web application logger without injection
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NgxWlog
NgxWlog (Angular Web Log) is an Angular logger that is inspired by the known NLog .NET logger.
Main feature are:
- Create named loggers from static method. Logger is not injectable so that you can even use it on static methods or non injected classes.
- Configure multiple loggers with filters and targets
- Manage log levels
- Reconfigure logs at runtime
Angular version is 12.0
Usage
Import module
In your app.module.ts
, import module NgxWlogModule
and using the forRoot
method configure your loggers.
Example:
@NgModule({
declarations: [AppComponent, AdminLayoutComponent, SidebarComponent, NavbarComponent],
imports: [
...,
NgxWlogModule.forRoot({
targets: [
{
appender: ColoredConsoleAppender,
name: 'console'
}
],
rules: [
{
name: '.*',
minLevel: LogLevel.Info,
writeTo: 'console'
}
]
}),
...
],
providers: [],
bootstrap: [AppComponent]
})
export class AppModule {
}
Create loggers
In your code your can create logger everywhere, simply by calling
LoggerFactory.createLogger('SomeLoggerName')
Example:
export class MyClass {
private static log = LoggerFactory.createLogger(MyClass.name);
static someSataticFunction() {
MyClass.log.info('Some message');
}
someClassMethod() {
const someObject = {};
MyClass.log.info('Some message', someObject);
}
}
LoggerFactory
createLogger method
As said above, LoggerFactory
provides a method that creates new logger for a specified context
name (a string). The context name will be used to identify witch logger is logging.
LoggerFactory.createLogger('SomeLoggerName')
Best practice is to create it in a static property. This to ensure that only one instance of logger is created by class or file. Also, you can use the class name where the logger is created (in case of class logger).
export class MyClass {
private static log = LoggerFactory.createLogger(MyClass.name);
}
If needed, you can create a logger for usages outside class contexts:
/**
* @file non-class.ts
*/
const log = LoggerFactory.createLogger('non-class.ts');
log.info('Some message');
Runtime configuration change
You can change the NgxWlog configuration at runtime. For that, prepare your
new configuration and simply call the LoggerFactory.reload(config: WlogConfig)
method.
const newConfig = {
...
} as NgxWlogConfig;
LoggerFactory.reload(newConfig);
Logging
As almost all loggers NgxWlog provides multiple log levels:
- Trace (very verbose)
- Debug
- Info
- Warn
- Error
- Fatal (should not happen)
To log in levels, simply use provided methods:
const log = LoggerFactory.createLogger('demo-levels');
log.trace('Some trace message');
log.debug('Some debug message');
log.info('Some info message');
log.warn('Some warn message');
log.error('Some error message');
log.fatal('Some fatal message');
You can also specify log level manually:
const log = LoggerFactory.createLogger('demo-manual-levels');
log.log(LogLevel.info, 'Some trace message');
Configuration
NgxWlog allow to configure the loggers. This to allow to have multiple loggers with multiple outputs and filters.
Targets
The targets configure where the logger will output logs. These are named appenders.
You can configure multiple targets.
Then te targets will be used by rules (see below).
A target expose some properties:
| Property | Description |
|----------|-------------------------------------------------------------------|
|name
| Required.Name of target that identifies it. It will be used into the rules.|
|appender
| Required.The type of appender that must implements interface Appender
|
|options
| Optional.An object that contains options for appender.This object will be passed to appender constructor.
Example:
NgxWlogModule.forRoot({
targets: [
{
appender: ColoredConsoleAppender,
name: 'console',
options: {
traceColor: 'green'
}
}
],
...
})
Rules
The rules define the loggers that will be created and witch target will use the logger.
| Property | Description |
|----------|-------------------------------------------------------------------|
|name
| Required.Regular expression to apply filter on logger context name.Use '*'
to get all logs (no filter).|
|minLevel
| Optional.Default: LogLevel.Trace
The minimal log level to apply. If log level is smaller NgxWlog will not write log. |
|maxLevel
| Optional.Default: LogLevel.Fatal
The maximal log level to apply. If log level is smaller NgxWlog will not write log. |
|writeTo
| Required.A list of targets with ,
, ;
or | char separator.
|active
| Optional.Default: true
Specify if logger is active or not. If not, nothing will be logged with this rule.
Example:
NgxWlogModule.forRoot({
...,
rules: [
{ // This rule will log all with level from Info to Error in the console and http target
name: '.*',
minLevel: LogLevel.Info,
maxLevel: LogLevel.Error,
writeTo: 'console,http',
active: true
},
{ // This rule will log only loggers called 'MyClass' only with level Error in the console target
name: 'MyClass',
minLevel: LogLevel.Error,
maxLevel: LogLevel.Error,
writeTo: 'http',
active: true
}
]})
Appenders
An appender is responsible to append log somewhere. This is the last step of a log.
By default NgxWlog provides by some appenders:
ConsoleAppender
ColoredConsoleAppender
ConsoleAppender
The ConsoleAppender
simply log to the browser console
. If possible, it uses the existing levels
of console
.
- Trace, Debug and Info logs to
console.log
- Warning logs to
console.warn
- Error and Fatal logs to
console.error
ColoredConsoleAppender
The ColoredConsoleAppender
log to the browser console
, but modify layout with colors.
Custom appender
You can also implement your own appender. You simply must implement interface
Appender
and use it in configuration.
By convention, the constructor should receive an options
parameter that has
the appender configuration options.
export class MyAppender implements Appender {
constructor(private options: any) {
}
append(level: LogLevel, data: any): void {
// Here simply redirect to console, but you can do whatever you want
console.log(`The level is '${level}'`, ...data);
}
}
TODO
- Implements tests
- Implements HttpClient appender
- Implements layout formatting
- Improve ColoredConsoleAppender to be customizable
- Handle log grouping