How to convert String to DateTime in Flutter and Dart

Last updated on February 12, 2022 Napoleon Loading... Post a comment

Overview

The DateTime class of the dart:core library provides 2 methods that can help you convert a string to DateTime:

  • DateTime.parse(String input): Constructs a new DateTime instance if the input is valid. Otherwise, throws a FormatException (Uncaught Error: FormatException: Invalid date format) when the input is not accepted.
  • DateTime.tryParse(String input): Constructs a new DateTime instance if the input is valid. Otherwise, returns Null instead of throwing a FormatException when you pass an unaccepted string to it.

What Are Accepted Strings

Not all strings can be converted to DateTime. A common pitfall that developers may face is that many strings that look like a valid date are NOT accepted, such as:

18-11-20222
Nov, 20 2022
19/11/2022
12/30/2023
...

According to the Flutter official docs, the accepted inputs are:

  • A date: A signed four-to-six digit year, two-digit month and two-digit day, optionally separated by – characters. Examples: “19700101”, “-0004-12-24”, “81030-04-01”.
  • An optional time part, separated from the date by either T or space. The time part is a two-digit hour, then optionally a two-digit minutes value, then optionally a two-digit seconds value, and then optionally a ‘.’ or ‘,’ followed by at least a one-digit second fraction. The minutes and seconds may be separated from the previous parts by a ‘:’. Examples: “12”, “12:30:24.124”, “12:30:24,124”, “123010.50”.
  • An optional time-zone offset part, possibly separated from the previous by a space. The time zone is either ‘z’ or ‘Z’, or it is a signed two-digit hour part and an optional two-digit minute part. The sign must be either “+” or “-“, and can not be omitted. The minutes may be separated from the hours by a ‘:’. Examples: “Z”, “-10”, “+01:30”, “+1130”.

Examples of accepted strings:

"2022-02-27"
"2022-02-27 13:27:00"
"2022-02-27 13:27:00.123456789z"
"2022-02-27 13:27:00,123456789z"
"20220227 13:27:00"
"20120227T132700"
"20220227"
"+20220227"
"2002-02-27T14Z"
"2002-02-27T14+00:00"
"-123450101 00:00:00 Z": in the year -12345.
"2002-02-27T14:00:00-0500": Same as "2002-02-27T19:00:00Z"

A Practical Example

The code:

void main() {
  const String input1 = '2012-02-27 13:27:00.123456789z'; // this is valid
  const String input2 = '2002-02-27T14+00:00'; // this is valid
  const String input3 = "2022 Feb 12"; // This will not be accepted

  final dt1 = DateTime.tryParse(input1);
  print(dt1);

  final dt2 = DateTime.tryParse(input2);
  print(dt2);

  final dt3 = DateTime.tryParse(input3);
  print(dt3);
}

Output:

2012-02-27 13:27:00.123456Z
2002-02-27 14:00:00.000Z
null

Conclusion

You’ve learned how to turn a string (an appropriate one) into a DateTime instance. If you’d like to explore more new and exciting about modern Flutter development, take a look at the following articles:

You can also check out our Flutter category page or Dart category page for the latest tutorials and examples.

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