react-native-android-log

Easy and useful log methods for Android apps in debug or release mode, with minimal impact.

Works with RN 0.50+, Gradle plugin 3.1.x and Gradle 4.4 or later.

Default build is for minSdkVersion 21 and targetSdkVersion 27, but you can configure this.

NOTE:

In iOS, the default level is SUPPRESS, which disables the output. If you change it, console.log will be used.

Install

1. Install the module from npm and link it:

   $ yarn add react-native-android-log
   $ react-native link react-native-android-log

2. Replace 'compile' with 'implementation' in your android/app/build.gradle. It must looks like:

   implementation project(':react-native-android-log')

For VS Code users

Optional: You can add the tag used by Log to the logCatArguments properties in .vscode/launch.json

This example will include React Native warnings and errors, and all the messages from App in the "OUTPUT" panel:

    ...
    {
      "name": "Debug Android",
      "program": "${workspaceRoot}/.vscode/launchReactNative.js",
      "type": "reactnative",
      "request": "launch",
      "platform": "android",
      "sourceMaps": true,
      "outDir": "${workspaceRoot}/.vscode/.react",
      "logCatArguments": [
        "*:S",
        "ReactNative:W",
        "ReactNativeJS:W",
        "App:V"
      ]
    },

SDK version Settings

Optional: In your android/build.gradle file, set the SDK versions that your app is using.

Example with the predefined values:

ext {
    def buildToolsVersion  = '27.0.3'
    def minSdkVersion      = 16
    def compileSdkVersion  = 27
    def targetSdkVersion   = 27
}

Usage

Log messages in your JavaScript files:

import Log from 'react-native-android-log'

// Set the default priority level (optional)
Log.setLevel(__DEV__ ? Log.VERBOSE : Log.WARN)

...
Log.v('Verbose message')    // no output in release builds
Log.w('Debugging')

// debugging message with amother tag:
Log.d('Proc2', 'warning')

...and see the output in the console through adb:

$ adb logcat -s App:V Proc2:V

or in the OUPUT panel of VS Code, if you are using the React Native Tools extension.

API

Contstants

Numeric levels, from most to least verbosity:

Constant	Description
VERBOSE	Used by Log.v, outputs nothing unless you use Log.setLevel(Log.VERBOSE)
DEBUG	Priority constant for Log.d
INFO	Priority constant for Log.i
WARN	Priority constant for Log.w
ERROR	Priority constant for Log.e
SUPPRESS	This is a special constant used to disable logging

Methods

• setTag(tag: string)

  Sets the tag to use by the logging methods without a tag parameter.

  The predefined tag is "App".

• setLevel(tag: string | null, level: number)

  Allows you to change the logging level for a specific tag or, if you pass a null tag, the default level for all the tags.

  The predefined level is DEBUG for debug builds and ERROR for release builds.

• getLevel(tag?: string | null)

  Return the level for a specific tag.

  If tag is null, not specified, or does not have a specific level, this method return the default level for all the tags.

• print(level: string, tag: string, msg: string)

• print(level: string, msg: string)

  Base method for all the one-letter logging methods.

• v (VERBOSE)

• d (DEBUG)

• i (INFO)

• w (WARN)

• e (ERROR)

  The above methods are one-letter shortcuts to the print method with the corresponding priority level and can be invoked with or without the tag parameter:

  method(tag: string, msg: string)

  method(msg: string)

  If you omit the tag, the one specified with setTag will be used, or the predefined tag "App".

License

MIT © 2018 Alberto Martínez