How to convert a list to a map in Dart

Overview

Dart provides methods to convert a list to a map, including:

• Map.fromIterable()
• orEach()

Map.fromIterable()

The fromIterable() method is used to create an instance of a Map from an iterable.

Let’s assume we have a class model:

class Student{
  String id;
  String name;

  Student(this.id, this.name);
}

We can convert List<Student> into Map, where:

• key: id
• value: name

Example

// Student's list
[{ 15GH1239, Maria}, { 15GH1243, Paul}, { 15GH1009, Jane}]

//Now to Map

// Map { id:name }
{15GH1239: Maria, 15GH1243: Paul, 15GH1009: Jane}

Let’s implement this example by writing a program to convert a list to a map.

Explanation

We create a class named Student with attributes id and name. Next, we use the class’s attributes to create a new list named *myList. Finally, we use Map.fromIterable() to convert the list to a map.

In the method for the first argument, we pass myList as an iterable. The method then calculates the key and value for each element of the iterable.

forEach()

The forEach() method iterates over an iterable such as a list.

The following code uses the same class and list as the previous example to demonstrate how to convert a list to a map.

Explanation

We use the forEach() method in line 19 to iterate through the list and add an entry (key, value) to the Map for each item in the list.