Introduction #

Velix is Dart/Flutter library implementing some of the core parts required in every Flutter application:

• type meta data
• specification and validation of type constraints
• general purpose mapping framework
• json mapper
• model-based two-way form data-binding
• i18n
• dependency injection container
• command pattern for ui actions

Check out some articles on Medium:

• General purpose mapper
• Commands
• Model driven Forms

Detailed information can be found in the corresponding Wiki.

Mapping #

A general purpose mapping framework let's you declaratively specify mappings:

 var mapper = Mapper([
        mapping<Money, Money>()
            .map(all: matchingProperties()),

        mapping<Product, Product>()
            .map(from: "status", to: "status")
            .map(from: "name", to: "name")
            .map(from: "price", to: "price", deep: true),

        mapping<Invoice, Invoice>()
            .map(from: "date", to: "date")
            .map(from: "products", to: "products", deep: true)
      ]);

var invoice = Invoice(...);

var result = mapper.map(invoice);

As a special case, json mapping is supported as well:

// overall configuration  

JSON(
   validate: true,
   converters: [Convert<DateTime,String>((value) => value.toIso8601String(), convertTarget: (str) => DateTime.parse(str))],
   factories: [Enum2StringFactory()]
);

// funny money class

@Dataclass()
@JsonSerializable(includeNull: true) // doesn't make sense here, but anyway...
class Money {
  // instance data

  @Attribute(type: "length 7")
  @Json(name: "c", required: false, defaultValue: "EU")
  final String currency;
  @Json(name="v", required: false, defaultValue: 0)
  @Attribute()
  final int value;

  const Money({required this.currency, this.value});
}

var price = Money(currency: "EU", value: 0);

var json = JSON.serialize(price);
var result = JSON.deserialize<Money>(json);

Installation #

The library is published on pub.flutter-io.cn