Logging large strings from Flutter

How about using the Flutter log from the dart: developer library. This does not seem to have the maximum length limit like print() or debugPrint(). This is the only solution that seems to work fine. Try it as below:

import 'dart:developer';


log(reallyReallyLongText);

The output will be the entire long string without breaks and prefixed with [log]

You can make your own print. Define this method

void printWrapped(String text) {
  final pattern = RegExp('.{1,800}'); // 800 is the size of each chunk
  pattern.allMatches(text).forEach((match) => print(match.group(0)));
}

Use it like

printWrapped("Your very long string ...");

Credit

Use debugPrint with the optional parameter to wrap according to the platform's output limit.

debugPrint(someSuperLongString, wrapWidth: 1024);

Currently dart doesn't support printing logs more than 1020 characters (found that out by trying).

So, I came up with this method to print long logs:

static void LogPrint(Object object) async {
    int defaultPrintLength = 1020;
    if (object == null || object.toString().length <= defaultPrintLength) {
       print(object);
    } else {
       String log = object.toString();
       int start = 0;
       int endIndex = defaultPrintLength;
       int logLength = log.length;
       int tmpLogLength = log.length;
       while (endIndex < logLength) {
          print(log.substring(start, endIndex));
          endIndex += defaultPrintLength;
          start += defaultPrintLength;
          tmpLogLength -= defaultPrintLength;
       }
       if (tmpLogLength > 0) {
          print(log.substring(start, logLength));
       }
    }
}

I have the perfect solution,It can be parsed no matter how long it is, and it is still in json format, Can be easily parsed or copied for use

import 'dart:developer';
import 'dart:convert';
...
...
log('${jsonEncode(responseData)}');

Here is a one-liner based on @CopsOnRoad's answer that you can quickly copy and paste (such as: when you want to slightly modify your code and log some data and see temporarily):

void printWrapped(String text) => RegExp('.{1,800}').allMatches(text).map((m) => m.group(0)).forEach(print);

You can use Flutter DevTools. It has a Logging View section with logs containing full string.

https://docs.flutter.dev/tools/devtools/logging

Please try debugPrint('your output'); instead of print('your output'); the documentation is here if you would like to read. debugPrint throttles the output to a level to avoid being dropped by android's kernel as per the documentation.

There is an open issue for that: https://github.com/flutter/flutter/issues/22665

debugPrint and print are actually truncating the output.

You can achieve this using the Logger Plugin: https://pub.dev/packages/logger

To print any type of log Just do the do the following.

  var logger = Logger();

  logger.d("Logger is working!");// It also accept json objects

In fact, it will even format the output for you.

Method 1

   void prints(var s1) {
        String s = s1.toString();
        debugPrint(" =======> " + s, wrapWidth: 1024);
      }

Method 2

void prints(var s1) {
  String s = s1.toString();
  final pattern = RegExp('.{1,800}');
  pattern.allMatches(s).forEach((match) => print(match.group(0)));
}

Just call this method to print your longggg string

If you run the application in android studio it will truncate long string.

In xcode 10.2 which i am using long string is not truncating.

My suggestion is write print statement logs and run the application in Xcode instead of android studio.

Same issue caused lot of frustration when I have to test base64 of images. I was using iTerm2 editor, so the answer is specific to the iTerm2

 1. Navigate to Preferences -> Profiles
 2. Select your Profile (in my case was **Default** only)
 3. Select **Terminal** in the header of right pan
 4. Check Unlimited scrollback

Now you can have copy the large strings from the terminal.