Flutter/Dart: Regex Replace with $2?

Question

I'm trying to grab just the id number from a Facebook picture URL using the replaceall regex method in Dart. What should I be using instead of $2 in the following code? The id number I need is between the "asid=" and "&height".

void main() {
 String faceavatar = 'https://platform-lookaside.fbsbx.com/platform/profilepic/?asid=10153806530149154&height=50&width=50&ext=1596623207&hash=AeSi1yDvk8TCqZql';
      String currentavatar = faceavatar.replaceAll(RegExp('(.*asid=)(\d*)height.*'), $2;
  print(currentavatar);
}

score 5 · Accepted Answer · 2020-07-06 11:05:45Z

5

You may try:

.*?\basid\b=(\d+).*

Explanation of the above regex:

.*? - Lazily matches everything except new-line before asid.
\basid\b - Matches asid literally. \b represents word boundary.
= - Matches = literally.
(\d+) - Represents first capturing group matching digits one or more times.
.* - Greedily everything except new-line zero or more times.
$1 - For the replacement part you can use $1 or match.group(1).

You can find the demo of above regex in here.

Sample Implementation in dart:

void main() {
 String faceavatar = 'https://platform-lookaside.fbsbx.com/platform/profilepic/?asid=10153806530149154&height=50&width=50&ext=1596623207&hash=AeSi1yDvk8TCqZql';
      String currentavatar = faceavatar.replaceAllMapped(RegExp(r'.*?\basid\b=(\d+).*'), (match) {
  return '${match.group(1)}';
});
  print(currentavatar);
}

You can find the sample run of the above implementation in here.

edited Jul 6, 2020 at 11:05

answered Jul 6, 2020 at 10:59

user7571182

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Comments

SHUVAM KUMAR · Accepted Answer · 2020-07-06 11:32:14Z

-1

just getting the asid:

(?<=(asid=))(\w|\d|\n|[().,\-:;@#$%^&*\[\]"'+–/\/®°⁰!?{}|]| )+?(?=(&height))

output: 10153806530149154

answered Jul 6, 2020 at 11:32

SHUVAM KUMAR

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