CODEWITHSUNDEEP
dartenums
rafitajaen
rafitajaen

Reputation: 469

Dart - Populate a Map programatically from an enum and a List

I want to populate a Map programatically but i don't know how to do that. Also i need that tagnameto be constant.

I made manually this, but if you have a thousand of Tag values, you have to write a thousand of lines of code: 

enum Tag { tag1, tag2, tag3, tag4, tag5 }

Map<Tag, String> tagname = {
  Tag.values[0]: 'Tag 1',
  Tag.values[1]: 'Tag 2',
  Tag.values[2]: 'Tag 3',
  Tag.values[3]: 'Tag 4',
  Tag.values[4]: 'Tag 5',
};

I want to populate tagname with:

const List<String> tagtitles = ['Tag 1', 'Tag 2', 'Tag 3', 'Tag 4'];

and if tagtitles.lenght < Tag.values.lenght then populate with 'empty' String.

Can you help me? Thanks.

Upvotes: 2

Views: 6830

Answers (2)

lrn
lrn

Reputation: 71713

The shortest way would probably be:

var tagName = {for (var tag in Tag.values)
    tag: (tag.index < tagTitles.length ? tagTitles[tag.index] : "empty")};

It still cannot be constant.

Upvotes: 1

nicolasproko
nicolasproko

Reputation: 101

If you assume that the tagTitles and the Tag enum have the same order of items, you can do the following: 

enum Tag { tag1, tag2, tag3, tag4 }

const List<String> tagTitles = ['Tag 1', 'Tag 2', 'Tag 3'];
Map<Tag, String> tagName = Map();
Tag.values.asMap().forEach((index, tag) =>
    tagName[tag] = index < tagTitles.length ? tagTitles[index] : 'empty');

The map will look something like this

{Tag.tag1: Tag 1, Tag.tag2: Tag 2, Tag.tag3: Tag 3, Tag.tag4: empty}

And you can use tagName[Tag.tag1] to access a item in the map.

Upvotes: 4

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