# Enum

## **How Enums Can Simplify Code**

```dart
enum PlanetType { terrestrial, gas, ice }
```

This is a basic **enum** that everyone knows. But what if your **enum** could:

* **Define itself in JSON** when received from a server
* **Automatically translate** into different languages
* **List all its values** dynamically
* **Search for values** within its own methods
* **Shorten conditional statements** significantly

In this article, I’ll show you **a different way to use enums**, turning a simple definition into **a powerful and efficient coding tool**.

Flutter is an **object-oriented** framework, and **encapsulation** is a key principle in OOP. Encapsulation hides the implementation details of an object and only allows interaction through **public methods**. This helps protect internal data, reduce errors, and improve maintainability.

Therefore, we can **incorporate all these useful functionalities** into a single **enum**, making it easier to use without worrying about its internal logic.

## **Defining Custom Fields in JSON**

Defining a custom field in JSON is introduced in the official documentation of **json\_serializable**:\
🔗 [json\_serializable - Enums](https://pub.dev/packages/json_serializable#enums)

Below is an example of how to set up an **enum** for `json_serializable`. The **enum** retrieves data from JSON based on the `'code'` field and converts it into an **enum value**.

For example, with the following JSON:

```json
{ "code" : 1 }
```

The corresponding **enum value** will be:

```dart
StateEnum.loading
```

We can replace `'code'` with any other field, such as `'title'`, depending on the requirements.

**Example Code:**

```dart
@JsonEnum(valueField: 'code')
enum StateEnum {
  notWorkingReady(0, "notWorkingReady"),
  loading(1, "loading"),
  notWorkingSuccess(3, "notWorkingSuccess"),
  notWorkingFailure(2, "notWorkingFailure");

  const StateEnum(this.code, this.title);

  final int code;
  final String title;
}
```

## **Shortening Conditional Code**

The second benefit that enums provide is reducing conditional code, making it easier to understand. Let's take a look at the following example:

```dart
@JsonEnum(valueField: 'code')
enum StateEnum {

    notWorkingReady( 0, "notWorkingReady"),
    loading( 1, "loading"),
    notWorkingSuccess( 3, "notWorkingSuccess"),
    notWorkingFailure( 2, "notWorkingFailure");
    
    // @override
    // int compareTo(PaddingWhiteLineEditEnum other) => code - other.code;
    
    const StateEnum( this.code, this.title);
    
    final int code;
    final String title;

    bool get isLoading => this == StateEnum.loading;

}
```

Writing concise conditions makes the code more readable and easier to understand, as shown below:

**New approach:**

```dart
if (state.isLoading) {
  
}
```

**Old approach:**

```dart
if (state == StateEnum.loading) {
  
}
```

## Language Translation

```dart
String get interpret => switch (this) {
      StateEnum.notWorkingReady => "Translate notWorkingReady",
      StateEnum.loading => "Translate loading",
      _ => "Translate other",
  };
```

I will write a separate article on. multi-language translation. You can check it out here

{% content-ref url="../ui/multi-language" %}
[multi-language](https://wong-coupon.gitbook.io/flutter/ui/multi-language)
{% endcontent-ref %}

## Retrieve Data from Enum Fields

Suppose I have the `code` field value and I want to find out which enum it corresponds to. I can create a function like this:

```dart
static ({StateEnum? getEnum, String? string})? getByCode(int? code) {
    try {
        final e = StateEnum.values.firstWhere((element) => element.code == code);
        return (getEnum: e, string: e.interpret);
    } catch (e) {
        return null;
    }
}
```

## Using Mason to Speed Up Enum Creation

With all the benefits listed above, using full-featured enums helps us write cleaner and faster code.

To generate a predefined template for your enums, consider using Mason. (If you're unfamiliar with Mason, check out this guide: [Boost Your Flutter Development Efficiency with Mason](https://mymoneycoupon.web.app/en/doc/help/flutter/boost-your-flutter-development-efficiency-with-mason))

{% content-ref url="../easy-code/mason" %}
[mason](https://wong-coupon.gitbook.io/flutter/easy-code/mason)
{% endcontent-ref %}

You can also check out my enum template and create a custom one for yourself and your colleagues:\
[dr\_enum on BrickHub](https://brickhub.dev/bricks/dr_enum)

[Buy Me a Coffee](https://buymeacoffee.com/ducmng12g) | [Support Me on Ko-fi](https://ko-fi.com/I2I81AEJG8)