Use of Dart extension Methods in existing APIs Class.

Extension Methods:

In this blog, we will check the use of Dart Extension methods in the flutter. Extension methods, introduced in Dart 2.7.

Sometimes we need additional functionalities which do not provide in existing libraries. We can add our own functionality by using the extension in the existing class of libraries’ APIs

Extension methods used to add additional functionality to existing libraries’ APIs. We can define extension with methods, getters, setters, and operators.

Extention Syntax:

extension <extension name> on <type> { 
(<member definition>)* 
}

extension <extension name> on <type> {

(<member definition>)*

}

Extention On String Class:

Let’s check some String Class extension examples.

extension StringExtension on String {

  bool get isNullOrEmpty {
    return this == null || this.isEmpty;
  }

  bool get isNotNullOrEmpty {
    return !(this == null || this.isEmpty);
  }

  get firstLetterToUpperCase {
    if (this != null)
      return this[0].toUpperCase() + this.substring(1);
    else
      return null;
  }

  get removeAllHtmlTags {
    if (this != null) {
      RegExp exp = RegExp(r"<[^>]*>", multiLine: true, caseSensitive: true);
      return this.replaceAll(exp, '');
    }
    else
      return null;
  }

}

extension StringExtension on String {

bool get isNullOrEmpty {

return this == null || this.isEmpty;

}

bool get isNotNullOrEmpty {

return !(this == null || this.isEmpty);

}

get firstLetterToUpperCase {

if (this != null)

return this[0].toUpperCase() + this.substring(1);

else

return null;

}

get removeAllHtmlTags {

if (this != null) {

RegExp exp = RegExp(r"<[^>]*>", multiLine: true, caseSensitive: true);

return this.replaceAll(exp, '');

}

else

return null;

}

Extention On List Class:

Let’s check some List Class extension examples.

extension ListExtension on List {
  bool get isNullOrEmpty {
    return this == null || this.isEmpty;
  }
}

extension ListExtension on List {

bool get isNullOrEmpty {

return this == null || this.isEmpty;

}

Using Extention methods:

You need to just import your extensions methods class and call Extention getter using dot(.) on variable

///Let's remove HTML tags from String

   String withoutHtmlTags = "String Contains Html Tags".removeAllHtmlTags;

   String fistLetterWithUpperCase = "String with lower case".firstLetterToUpperCase;

///Let's remove HTML tags from String

String withoutHtmlTags = "String Contains Html Tags".removeAllHtmlTags;

String fistLetterWithUpperCase = "String with lower case".firstLetterToUpperCase;

I hope this blog will help to add some utility functionality to existing APIs.

Happy Learning 🙂

Reference Links:https://dart.dev/guides/language/extension-methods

yogendra singh 31 March 2021

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Flutter: Use of Dart extension Methods.

Extension Methods:

Extention Syntax:

Extention On String Class:

Extention On List Class:

Using Extention methods:

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Flutter: Use of Dart extension Methods.

Extension Methods:

Extention Syntax:

Extention On String Class:

Extention On List Class:

Using Extention methods:

Leave a Comment Cancel Reply

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