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About a .NET 5 (RC1) Web application with GraphQL 3

antoniofalcao profile image Antonio Falcão Jr. Updated on ・6 min read

Yesterday (09/14) was released the first version (RC1) from .NET 5, ASP.NET, EF Core and C# 9.

Still talking about releases, since last week is available the version 3 from GraphQL for .NET.

On occasion, this project exemplify the implementation and Dockerization of a simple Razor Web MVC Core consuming an GraphQL 3 Web API, build in a .NET 5 multilayer project, considering development best practices, like SOLID and DRY, applying Domain-Driven concepts in a Hexagonal Architecture.

GitHub logo AntonioFalcao / Dotnet5.GraphQL3.WebApplication

This project exemplify the implementation and dockerization of a simple Razor Web MVC Core consuming a full GraphQL 3 Web API, build in a .NET 5 multi-layer project, considering development best practices, like SOLID and DRY, applying Domain-Driven concepts in a Hexagonal Architecture.


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Highlights

Notifications (pattern/context)

To avoid handle exceptions, was implemented a NotificationContext that's allow all layers add business notifications through the request, with support to receive Domain notifications, that by other side, implement validators from Fluent Validation and return a ValidationResult.

protected bool OnValidate<TEntity>(TEntity entity, AbstractValidator<TEntity> validator)
{
    ValidationResult = validator.Validate(entity);
    return IsValid;
}

protected void AddError(string errorMessage, ValidationResult validationResult = default)
{
    ValidationResult.Errors.Add(new ValidationFailure(default, errorMessage));
    validationResult?.Errors.ToList().ForEach(failure => ValidationResult.Errors.Add(failure));
}
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To GraphQL the notification context delivers a ExecutionErrors that is propagated to result from execution by a personalized Executer:

var result = await base.ExecuteAsync(operationName, query, variables, context, cancellationToken);
var notificationContext = _serviceProvider.GetRequiredService<INotificationContext>();

if (notificationContext.HasNotifications)
{
    result.Errors = notificationContext.ExecutionErrors;
    result.Data = default;
}
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Resolving Scoped dependencies with Singleton Schema.

Is necessary, in the same personalized Executer to define the service provider that will be used for resolvers on fields:

var options = base.GetOptions(operationName, query, variables, context, cancellationToken);
options.RequestServices = _serviceProvider;
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Abstractions

With abstract designs, it is possible to reduce coupling in addition to applying DRY concepts, providing resources for the main behaviors:

...Domain.Abstractions

public abstract class Entity<TId>
    where TId : struct
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public abstract class Builder<TBuilder, TEntity, TId> : IBuilder<TEntity, TId>
    where TBuilder : Builder<TBuilder, TEntity, TId>
    where TEntity : Entity<TId>
    where TId : struct
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...Repositories.Abstractions

public abstract class Repository<TEntity, TId> : IRepository<TEntity, TId>
    where TEntity : Entity<TId>
    where TId : struct
{
    private readonly DbSet<TEntity> _dbSet;

    protected Repository(DbContext dbDbContext)
    {
        _dbSet = dbDbContext.Set<TEntity>();
    }
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...Services.Abstractions

public abstract class Service<TEntity, TModel, TId> : IService<TEntity, TModel, TId>
    where TEntity : Entity<TId>
    where TModel : Model<TId>
    where TId : struct
{
    protected readonly IMapper Mapper;
    protected readonly INotificationContext NotificationContext;
    protected readonly IRepository<TEntity, TId> Repository;
    protected readonly IUnitOfWork UnitOfWork;

    protected Service(
        IUnitOfWork unitOfWork,
        IRepository<TEntity, TId> repository,
        IMapper mapper,
        INotificationContext notificationContext)
    {
        UnitOfWork = unitOfWork;
        Repository = repository;
        Mapper = mapper;
        NotificationContext = notificationContext;
    }
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public abstract class MessageService<TMessage, TModel, TId> : IMessageService<TMessage, TModel, TId>
    where TMessage : class
    where TModel : Model<TId>
    where TId : struct
{
    private readonly IMapper _mapper;
    private readonly ISubject<TMessage> _subject;

    protected MessageService(IMapper mapper, ISubject<TMessage> subject)
    {
        _mapper = mapper;
        _subject = subject;
    }
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From EF TPH to GraphQL Interface

GraphQL interfaces provide a very interesting way to represent types derived from entities. In turn, in EF Core we can structure with TPH.

ENTITY

public class ProductConfig : IEntityTypeConfiguration<Product>
{
    public void Configure(EntityTypeBuilder<Product> builder)
    {
        builder
            .HasDiscriminator()
            .HasValue<Boot>(nameof(Boot))
            .HasValue<Kayak>(nameof(Kayak))
            .HasValue<Backpack>(nameof(Backpack));
    }
}
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INHERITOR

public class KayakConfig : IEntityTypeConfiguration<Kayak>
{
    public void Configure(EntityTypeBuilder<Kayak> builder)
    {
        builder
            .HasBaseType<Product>();
    }
}
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INTERFACE

public sealed class ProductInterfaceGraphType : InterfaceGraphType<Product>
{
    public ProductInterfaceGraphType(BootGraphType bootGraphType, BackpackGraphType backpackGraphType, KayakGraphType kayakGraphType)
    {
        Name = "product";

        ResolveType = @object =>
        {
            return @object switch
            {
                Boot _ => bootGraphType,
                Backpack _ => backpackGraphType,
                Kayak _ => kayakGraphType,
                _ => default
            };
        };
    }
}
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OBJECT

public sealed class KayakGraphType : ObjectGraphType<Kayak>
{
    public KayakGraphType()
    {
        Name = "kayak";
        Interface<ProductInterfaceGraphType>();
        IsTypeOf = o => o is Product;
    }
}
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Environment configuration

Development

Secrets

To configure database resource, init secrets in https://github.com/AntonioFalcao/Dotnet5.GraphQL3.WebApplication/tree/master/src/Dotnet5.GraphQL3.Store.WebAPI, and then define the DefaultConnection:

dotnet user-secrets init
dotnet user-secrets set "ConnectionStrings:DefaultConnection" "Server=localhost,1433;Database=Store;User=sa;Password=!MyComplexPassword"
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After this, to configure the HTTP client, init secrets in https://github.com/AntonioFalcao/Dotnet5.GraphQL3.WebApplication/tree/master/src/Dotnet5.GraphQL3.Store.WebMVC and define Store client host:

dotnet user-secrets init
dotnet user-secrets set "HttpClient:Store" "http://localhost:5000/graphql"
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AppSettings

If you prefer, is possible to define it on WebAPI appsettings.Development.json and WebMVC appsettings.Development.json files:

WebAPI

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=localhost,1433;Database=Store;User=sa;Password=!MyComplexPassword"
  }
}
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WebMCV

{
  "HttpClient": {
    "Store": "http://localhost:5000/graphql"
  }
}
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Production

Considering use Docker for CD (Continuous Deployment). On respective compose both web applications and sql server are in the same network, and then we can use named hosts. Already defined on WebAPI appsettings.json and WebMVC appsettings.json files:

AppSettings

WebAPI

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=mssql;Database=Store;User=sa;Password=!MyComplexPassword"
  }
}
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WebMCV

{
  "HttpClient": {
    "Store": "http://webapi:5000/graphql"
  }
}
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Running

The ./docker-compose.yml provide the WebAPI, WebMVC and MS SQL Server applications:

docker-compose up -d
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GraphQL Playground

By default Playground respond at http://localhost:5000/ui/playground but is possible configure the host and many others details in ../...WebAPI/GraphQL/DependencyInjection/Configure.cs

app.UseGraphQLPlayground(
    new GraphQLPlaygroundOptions
    {
        Path = "/ui/playground",
        BetaUpdates = true,
        RequestCredentials = RequestCredentials.Omit,
        HideTracingResponse = false,

        EditorCursorShape = EditorCursorShape.Line,
        EditorTheme = EditorTheme.Dark,
        EditorFontSize = 14,
        EditorReuseHeaders = true,
        EditorFontFamily = "JetBrains Mono"
    });
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Queries

Fragment for comparison and Arguments

QUERY

{
  First: product(id: "2c05b59b-8fb3-4cba-8698-01d55a0284e5") {
    ...comparisonFields
  }
  Second: product(id: "65af82e8-27f6-44f3-af4a-029b73f14530") {
    ...comparisonFields
  }
}

fragment comparisonFields on Product {
  id
  name
  rating
  description
}
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RESULT

{
  "data": {
    "First": {
      "id": "2c05b59b-8fb3-4cba-8698-01d55a0284e5",
      "name": "libero",
      "rating": 5,
      "description": "Deleniti voluptas quidem accusamus est debitis quisquam enim."
    },
    "Second": {
      "id": "65af82e8-27f6-44f3-af4a-029b73f14530",
      "name": "debitis",
      "rating": 10,
      "description": "Est veniam unde."
    }
  }
}
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Query named's and Variables

QUERY

query all {
  products {
    id
    name
  }
}

query byid($productId: ID!) {
  product(id: $productId) {
    id
    name
  }
}
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VARIABLES

{
  "productId": "2c05b59b-8fb3-4cba-8698-01d55a0284e5"
}
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HTTP BODY

{
    "operationName": "byid",
    "variables": {
        "productId": "2c05b59b-8fb3-4cba-8698-01d55a0284e5"
    },
    "query": "query all {
        products {
          id
          name
        }
    }
    query byid($productId: ID!) {
        product(id: $productId) {
          id
          name
        }
    }"
}
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PLAYGROUND

queries


Variables with include, skip and default value

QUERY

query all($showPrice: Boolean = false) {
  products {
    id
    name
    price @include(if: $showPrice)
    rating @skip(if: $showPrice)
  }
}
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VARIABLES

{
  "showPrice": true
}
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HTTP BODY

{
    "operationName": "all",
    "variables": {
        "showPrice": false
    },
    "query": "query all($showPrice: Boolean = false) {
          products {
            id
            name
            price @include(if: $showPrice)
            rating @skip(if: $showPrice)
          }
    }"
}
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Mutations

MUTATION

Creating / adding a new Review to the respective product.

mutation($review: reviewInput!) {
  createReview(review: $review) {
    id
  }
}
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VARIABLES

{
  "review": {
    "title": "some title",
    "comment": "some comment",
    "productId": "0fb8ec7e-7af1-4fe3-a2e2-000996ffd20f"
  }
}
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RESULT

{
  "data": {
    "createReview": {
      "title": "some title"
    }
  }
}
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Subscriptions

SUBSCRIPTION

The Mutation stay listening if a new review is added.

subscription {
  reviewAdded {
    title
  }
}

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RESULT

{
  "data": {
    "reviewAdded": {
      "title": "Some title"
    }
  }
}
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Built With

Microsoft Stack - v5.0 (RC 1)

GraphQL Stack - v3.0 (preview/alpha)

  • GraphQL - GraphQL is a query language for APIs and a runtime for fulfilling those queries with data;
  • GraphQL for .NET - This is an implementation of GraphQL in .NET;
  • GraphQL.Client - A GraphQL Client for .NET over HTTP;
  • GraphQL Playground - GraphQL IDE for better development workflows.

Community Stack

  • AutoMapper - A convention-based object-object mapper;
  • FluentValidation - A popular .NET library for building strongly-typed validation rules;
  • Bogus - A simple and sane fake data generator for C#, F#, and VB.NET;
  • Bootstrap - The most popular HTML, CSS, and JS library in the world.

GitHub logo AntonioFalcao / Dotnet5.GraphQL3.WebApplication

This project exemplify the implementation and dockerization of a simple Razor Web MVC Core consuming a full GraphQL 3 Web API, build in a .NET 5 multi-layer project, considering development best practices, like SOLID and DRY, applying Domain-Driven concepts in a Hexagonal Architecture.

Discussion (3)

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azmimansur profile image
AZMIMANSUR

I just try to add migrations, found error : Unable to create an object of type 'StoreDbContext'. For the different patterns supported at design time, see go.microsoft.com/fwlink/?linkid=85...

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antoniofalcao profile image
Antonio Falcão Jr. Author

Hello AZMIMANSUR!

This project has the database context in a different layer than the entry point.

To perform migrations, in this case, you must indicate both projects in the command:

dotnet ef migrations add "new_migration" -p .\src\Dotnet5.GraphQL3.Store.Repositories\ -s .\src\Dotnet5.GraphQL3.Store.WebAPI\
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AZMIMANSUR

Thanks, Antonio

Working now.