Gestión del Estado con Provider en Flutter

Managing status in Flutter can be easy if we use appropriate tools such as the Provider library. Before implementing it, it is crucial to correctly structure the data using a model that defines the necessary attributes. In the following, you will learn how to create a model in Flutter to manage recipes.

How to create the data structure of a model?

• In the lib folder of the project, create a new folder to store the models.
• Inside this folder, generate a file called recipe_model.dart.
• Define a class called Recipe that contains the necessary attributes:
  • name (String): the name of the recipe.
  • author (String): the author of the recipe.
  • imageLink (String): link to the image.
  • steps (List): steps of the recipe as a list.

How to implement the constructor of the class?

• Define a constructor with the required modifier to ensure that all attributes are required.
• Correct any errors in the variable names to maintain consistency (e.g., use upper or lower case correctly).

class Recipe {  final String name; final String author; final String imageLink; final List<String>steps; Recipe({ required this.name, required this.author, required this.imageLink, required this.steps, }); }

What is a factory and how is it implemented?

• A factory allows you to convert data from a JSON into a class instance.
• It uses fromJson to map each attribute of the JSON to the corresponding attribute in the class.

factory Recipe.fromJson(Map<String, dynamic>json) { return Recipe( name: json['name'], author: json['author'], imageLink: json['imageLink'], steps: List<String>.from(json['steps']), ); ); }

• Implements the toJson method to perform the reverse conversion, transforming the class into a JSON format.

Map<String, dynamic>toJson() { return { ' name': name, ' author': author, ' imageLink': imageLink, ' steps': steps, }; }; }

How to improve model debugging?

• Add the toString method using @override to display the variables in console when printing the object.
• This helps to visualize the data during the development process.

@overrideString toString() { return 'Recipe(name: $name, author: $author, imageLink: $imageLink, steps: $steps)'; }

How does this model benefit the use of Provider?

A well-structured model ensures that state management is more efficient. By combining this model with Provider, you can update recipe data in real time, allowing for centralized and dynamic data management in your application.