cqrs library

A library for convenient communication with CQRS-compatible backends, using queries and commands.

Example:

final apiUri = Uri.parse('https://flowers.garden/api/');

final cqrs = Cqrs(
  loginClient,
  apiUri,
);

// Fetching first page of flowers
final flowers = await cqrs.get(AllFlowers(page: 1));

// Handling query result
if (flowers case QuerySuccess(:final data)) {
  print(data);
} else if (flowers case QueryFailure(:final error)) {
  print('Something failed with error $error');
}

// Adding a new flower
final result = await cqrs.run(
  AddFlower(
    name: 'Daisy',
    pretty: true,
  ),
);

// Handling command result
if (result case CommandSuccess()) {
  print('Flower added succefully');
} else if (result case CommandFailure(isInvalid: true, :final validationErrors)) {
  print('Validation errors occured');
  handleValidationErrors(validationErrors);
} else if (result case CommandFailure(:final error)) {
  print('Something failed with error ${error}');
}

See also:

https://github.com/leancodepl/corelibrary
https://github.com/leancodepl/contractsgenerator - code generation tool for easy contracts transpilation from C# to Dart and TypeScript.
https://github.com/leancodepl/contractsgenerator-dart - dart code contract generator.

Classes

Command

Command carrying data related to performing a certain action on the backend.

CommandFailure

Class which represents a result of unsuccesful command execution.

CommandResult

Result class for CQRS command result. Can be either CommandSuccess or CommandFailure.

CommandSuccess

Class which represents a result of succesful command execution.

Cqrs

Class used for communicating with the backend via queries and commands.

CqrsMethod

An interface for contracts that can be serialized and sent to the backend.

CqrsMiddleware

Abstract class for CQRS result handlers. Can be used to specify certain behaviors that will be triggered for given errors i.e. showing snackbar on network error or logging out on authetication error etc.

Operation<T>

Operation describing a criteria for a query, a command, and the results it returns.

OperationFailure<T>

Generic class which represents a result of unsuccesful operation execution.

OperationResult<T>

Generic result for CQRS operation result. Can be either OperationSuccess or OperationFailure.

OperationSuccess<T>

Generic class which represents a result of succesful operation execution.

Query<T>

Query describing a criteria for a query and the results it returns.

QueryFailure<T>

Generic class which represents a result of unsuccesful query execution.