iodigital-com/traineeship-dotnet-mycommute-implementing-business-logic

This module focuses on implementing business logic in services. You will learn how to define an interface. Then implement that interface in a service class. You will learn how to set up a test project to unit test the business logic implementation.

Implementing Business Logic

This module focuses on implementing business logic in services. You will learn how to define an interface. Then implement that interface in a service class. You will learn how to set up a test project to unit test the business logic implementation.

Topics

• Interfaces & implementations
• Namespaces
• Asynchronous programming
• Working with collections & LINQ
• Unit testing & integration testing with NUnit
• NuGet management

Prerequisites

You'll need to set up your machine to run .NET, including the C# 10.0 compiler. Download & install the .NET 6 SDK.

You'll need a connection string to an SQL Server database.

Requirements

We are going to create an application that keeps track of the modes of transport that a company's employees use to commute to work daily. The full solution will include:

• Data project: defines the data structure
• Domain project: business logic implementations
• WebApplication project: includes the web API's & backoffice web application to manage the employee data
• Mobile app project: will be used by the employees to input the mode of transport for their daily commute

The data layer is already implemented in the previous module. Now we are going to implement the domain layer. During development, run the included (unit) tests to get feedback on your progress. Once a test passes, move on the making the next test pass.

Assignments

Create a new class library project

Create a new class library project and name it MyCommute.Domain This project will contain the domain logic for handling employees & commutes.

Define interface IEmployeeService

The EmployeeService will handle CRUD operations related to the MyCommute.Data.Entities.Employee entity (further referred to as Employee). It also contains methods to fetch employee data. In project MyCommute.Domain, create a new directory Services. In the Services directory, define an interface IEmployeeService.

IEmployeeService declares:

• GetAsync: accepts no parameters, and returns a collection of all Employee entities in the database.
• GetByIdAsync: accepts 1 parameters of type Guid and returns one Employee that matches the provided id.
• GetByEmailAsync" accepts 1 parameter of type string and returns one Employee that matches the provided email address.
• AddAsync: accepts 1 parameter of type Employee and returns the Employee entity after saving it to the database.
• UpdateAsync: accepts 1 parameter of type Employee and returns the Employee entity after saving it to the database.
• DeleteAsync: accepts 1 parameters of type Guid and returns type bool to indicate success after removing the Employee matching the provided id from the database.
• DeleteAsync: accepts 1 parameters of type string and returns type bool to indicate success after removing the Employee matching the provided email address from the database.

Implement IEmployeeService in EmployeeService

In the Services directory, create a new directory Implementations. In that directory, create a new class and name it EmployeeService.

EmployeeService implements interface IEmployeeService:

public class EmployeeService : IEmployeeService

EmployeeService has a private, read-only field dataContext of type MyCommute.Data.Entities.DataContext (further referred to as DataContext).

private readonly DataContext dataContext;

The constructor of EmployeeService accepts 1 argument of type DataContext, and initializes the dataContext field.

public EmployeeService(DataContext context)
{
    dataContext = context;
}

The methods declared in IEmployeeService are implemented in EmployeeService:

• GetAsync: accepts no parameters, and returns a collection of all Employee entities in the database.
• GetByIdAsync: accepts 1 parameters of type Guid and returns one Employee that matches the provided id.
• GetByEmailAsync: accepts 1 parameter of type string and returns one Employee that matches the provided email address.
• AddAsync: accepts 1 parameter of type Employee and returns the Employee entity after saving it to the database.
• UpdateAsync: accepts 1 parameter of type Employee and returns the Employee entity after saving it to the database. Throws EmployeeNotFoundException when no matching Employee is found.
• DeleteAsync: accepts 1 parameters of type Guid and returns type bool to indicate success after removing the Employee matching the provided id from the database. Throws EmployeeNotFoundException when no matching Employee is found.
• DeleteAsync: accepts 1 parameters of type string and returns type bool to indicate success after removing the Employee matching the provided email address from the database. Throws EmployeeNotFoundException when no matching Employee is found.

Define interface ICommuteService

The CommuteService will handle CRUD operations related to the MyCommute.Data.Entities.Commute entity (further referred to as Commute). It also contains methods to fetch commute data. In the Services directory, define an interface ICommuteService.

ICommuteService declares:

• GetAsync: accepts 1 parameters of type Guid and returns one Commute that matches the provided id.
• GetAllAsync: accepts no parameters, and returns a collection of all Commute entities in the database.
• GetByUserIdAsync: accepts 1 parameters of type Guid and returns a collection of all Commute entities related to the Employee that matches the provided id.
• AddAsync: accepts 1 parameter of type Commute and returns the Commute entity after saving it to the database.
• UpdateAsync: accepts 1 parameter of type Commute and returns the Commute entity after saving it to the database.
• DeleteAsync: accepts 1 parameters of type Guid and returns type bool to indicate success after removing the Commute matching the provided id from the database.

Implement ICommuteService in CommuteService

In the Implementations directory, create a new class and name it CommuteService.

CommuteService implements interface ICommuteService.

CommuteService has a private, read-only field dataContext of type DataContext. The constructor of CommuteService accepts 1 argument of type DataContext, and initializes the dataContext field.

The methods declared in ICommuteService are implemented in CommuteService:

• GetAsync: accepts 1 parameters of type Guid and returns one Commute that matches the provided id. Throws CommuteNotFoundException when no matching Commute is found.
• GetAllAsync: accepts no parameters, and returns a collection of all Commute entities in the database. Throws CommuteNotFoundException when no matching Commute is found.
• GetByUserIdAsync: accepts 1 parameters of type Guid and returns a collection of all Commute entities related to the Employee that matches the provided id.
• AddAsync: accepts 1 parameter of type Commute and returns the Commute entity after saving it to the database.
• UpdateAsync: accepts 1 parameter of type Commute and returns the Commute entity after saving it to the database. Throws CommuteNotFoundException when no matching Commute is found.
• DeleteAsync: accepts 1 parameters of type Guid and returns type bool to indicate success after removing the Commute matching the provided id from the database. Throws CommuteNotFoundException when no matching Commute is found.

Add Date property to the Commute class and generate a migration

A frequently occurring task during development is updating the properties of an existing entity, and generating a migration to update the database schema. While implementing the CommuteService, we realised that the Commute entity is missing a timestamp to indicate which date the commute relates to. Add a new property Date with type DateTime. Then generate a migration.

Create Address model

Before starting implementation of the GeoCodeService, first create a new Address record

Properties:

• Street (string)
• HouseNumber (string)
• ZipCode (string)
• City (string)
• Country (string)

Define interface IGeoCodeService

The GeoCodeService features methods for geocoding an address to geographic coordinates (longitude & latitude), and the reverse operation of retrieving an address from geographical coordinates. In the Services directory, define an interface IGeoCodeService.

IGeoCodeService declares:

• GetCoordinatesForAddressAsync: accepts 1 parameter of type Address and returns one NetTopologySuite.Geometries.Point (further referred to as Point).
• GetAddressForCoordinatesAsync: accepts 1 parameter of type Point and returns one Address.

Implement IGeoCodeService in GeoCodeService

A number of geocoding & reverse geocoding API's are publicly available, as well as NuGet packages to consume those API's. You are free to choose which API and/or NuGet package you want to use.

The methods declared in IGeoCodeService are implemented in GeoCodeService:

• GetCoordinatesForAddressAsync: accepts 1 parameter of type Address and returns one Point. Throws ForwardGeoCodeFailedException when no geographical coordinates could be found for the given address.
• GetAddressForCoordinatesAsync: accepts 1 parameter of type Point and returns one Address. Throws ReverseGeoCodeFailedException when the given geographical coordinates could be resolved to an address.