Skip to main content

Part-1 An Overview On GraphQL Implementation In .Net Application Using Hot Chocolate Library

In this article, we are going to understand the implementation steps of GraphQL in .Net5 application using Hot Chocolate Library.

GraphQL:

GraphQL is an open-source data query and manipulation language for APIs. It is a query language for your API and a server-side runtime for executing queries by using a type system you define for your data. GraphQL can be integrated into any framework like .Net, Java, NetsJS, etc and it isn't tied to any specific database or storage engine and instead backed by your existing code and data.

GraphQL caries two important operations:

  • Query - fetching data
  • Mutation - save or update.

Hot Chocolate GraphQL:

Hot Chocolate is an open-source GraphQL server that is compliant with the newest GraphQL latest specs. It is the wrapper library of the original .Net GraphQL library. Hot Chocolate takes the complexity away from building a fully-fledged GraphQL server.

An Overview On GrphQL SDL(Schema Definition Language):

A syntax to data query and manipulation in GraphQL called SDL(schema definition language). GraphQL SDL syntax looks similar to the javascript object. Hot Chocolate GraphQL library providers flexibility to develop GraphQL endpoint either using Schema First approach(purely uses GraphQL SDL syntax) or using Code First approach(in this approach framework will take responsibility of generating GraphQL SDL implicitly for dotnet developers this will be ideal approach). So this section is to get familiar with GraphQL SDL syntax for better understanding.

GraphQL SDL syntax to define 'type'(in c# class is equivalent to the GraphQL SDL 'type') object(in c# it is like our database table representing class). 

type Book {
  Id: Int
  Name: String
}
  • Here we defined the 'Book' GraphQL SDL type object. Its properties are 'Id', 'Name'. Its properties types are like 'Int', 'String' are GraphQL scalar types.
GraphQL SDL syntax to define the Query type. 
type Query {
  book: Book
}
  • This 'Query type' is an entry point to fetch data. It contains all resolvers(means logic to fetch data).
  • Here we define 'book: Book' means on requesting 'book' query we get a response of single object of type 'Book', similarly we need to define all fetch logic inside of the 'Query'.
GraphQL SDL syntax to define the Mutation type. 
type Mutation{
  create(book:BookInput):Book
}
  • The 'Mutation type' contains all the logic for saving or updating the data.
  • Here 'create(book: BookInput)' is the resolver method to save data.
GraphQL SDL syntax to define the Schema type. 
type Schema{
  query:Query,
  mutaition:Mutation
}
  • Schema is the root type in GraphQL where 'Query' and 'Mutations' registered.
Note: No need to remember all the syntax above mentioned here I'm going to explain integration using a code-first approach where we don't need to write SDL syntax.

Create A .Net5 Web API Application:

Let's create a .Net5 Web API application in which we are going to integrate GraphQL. For development, any IDE can be used but most preferred are Visual Studio 2019(Version 16.8.* that supports .Net5) or Visual Studio Code.

Hot Chocolate Library:

Package Manager Command:
Install-Package HotChocolate.AspNetCore -Version 11.0.2
.Net CLI Command:
dotnet add package HotChocolate.AspNetCore -Version 11.0.2

Register GraphQL Service And Endpoint:

First we need to register our GraphQL service that is 'AddGraphQLServer()'. This 'AddGraphQLServer()' extension method enables schema and executor.
Startup.cs:(ConfigureServices Method)
services.AddGraphQLServer();
Now configure GraphQL endpoint.
Startup.cs:(Configure Method) 
app.UseEndpoints(endpoints =>
{
  endpoints.MapGraphQL();
  endpoints.MapControllers();
});

POCO Class And GraphQL ObjectType:

A plain class is a general used to represent a table for fetching the data in .Net application. So lets create a POCO(Plain Old CLR Object) class that will type for our data return form the server.
Data/Entities/Gadgets.cs:
namespace HC.GraphQL.Sample.Data.Entities
{
  public class Gadgets
  {
   public int Id { get; set; }
   public string ProductName { get; set; }
   public string Brand { get; set; }
   public decimal Cost { get; set; }
   public string Type { get; set; }
  }
}
Now GraphQL doesn't understand our 'Gadget.cs' .net class because GraphQL can only understand SDL syntax. So to make our POCO class understand by GraphQL we need to map it with 'HotChocolate.Types.ObjectType'. In this 'ObjectType' we need to register all our POCO class properties so that on runtime 'ObjecType' generates GraphQL SDL type which is understandable by the GraphQL execution schema.
So let's create a 'HotChocolate.Types.ObjectType' for our 'Gadget' class.
ObjectTypes/GadgetsObjectType.cs:
using HC.GraphQL.Sample.Data.Entities;
using HotChocolate.Types;

namespace HC.GraphQL.Sample.ObjectTypes
{
  public class GadgetsObjectType : ObjectType<Gadgets>
  {
   protected override void Configure(IObjectTypeDescriptor<Gadgets> descriptor)
   {
	descriptor.Field(g => g.Id).Type<IntType>().Name("Id");
	descriptor.Field(g => g.ProductName).Type<StringType>().Name("ProductName");
	descriptor.Field(g => g.Brand).Type<StringType>().Name("Brand");
	descriptor.Field(g => g.Cost).Type<DecimalType>().Name("Cost");
	descriptor.Field(g => g.Type).Type<StringType>().Name("Type");
   }
  }
}
  • Here we create 'GadgetsObjectType' that inherits 'HotChocolate.Types.ObjectType<Gadgets>'.
  • Inside the 'Configure' method we are registering the properties of 'Gadget' classes as the 'Field' to the ObjectType.
  • Here 'IntType','StringType','DecimalType' are scalar types provided by the HotChocolate GraphQL library.
  • The 'Name()' extension method to define the name of each 'Field' registered.
Now on runtime, the 'GadgetsObjectType' generates the GraphQL type as below 
type Gadgets{
    Id: Int,
    ProductName: String,
    Brand:String,
    ....
}

Create Query And Its ObjectType:

In GraphQL 'Query' type is the entry point for fetching the data. So let's create our query class.
SchemaCore/Query.cs:
using HC.GraphQL.Sample.Data.Entities;

namespace HC.GraphQL.Sample.SchemaCore
{
  public class Query
  {
   public Gadgets FirstGadget()
   {
	return new Gadgets{
	 Id = 1,
	 ProductName = "Samsung M30s",
	 Brand = "Samsung",
	 Cost = 15000,
	 Type = "Mobile"
	};
   }
  }
}
  • Here 'FirstGadget()' method is our resolver method where we fetching a single record.
Since 'Query' is a normal c# class we need to create an ObjectType for it.
ObjectTypes/QueryObjectType.cs:
using HC.GraphQL.Sample.SchemaCore;
using HotChocolate.Types;

namespace HC.GraphQL.Sample.ObjectTypes
{
  public class QueryObjectType:ObjectType<Query>
  {
   protected override void Configure(IObjectTypeDescriptor<Query> descriptor)
   {
	descriptor.Field(g => g.FirstGadget())
	.Type<GadgetsObjectType>().Name("FirstGadget");
   }
  }
}
  • Here we registered our resolver method 'FirsGadget()' as a field for QueryObjectType. 
  • Defined its 'Type' as 'GadgetsObjectType'(This GadgetObjectType represents our c# gadget class for GraphQL).
  • The 'Name' extension method defines the name for the field.
On runtime, this QueryObjectType represents the schema like as below. 
type Query{
  FirstGadget: Gadgets
}

Register Query:

Now we need to register our 'QueryObjectType' in the Startup file
Startup.cs:(ConfigureServices Method)
services.AddGraphQLServer()
.AddQueryType<QueryObjectType>();

Fields:

GraphQL is about asking for specific fields on objects on the server. Let's test API by requesting Fields.
Request Query:
query{
  FirstGadget{
   Brand
   ProductName
  }
}
  • Here 'query' to invoke the 'QueryObjectType'. The name 'FirstGadget' should match with the registered name in 'QueryObjectType' so this will invoke the specific resolver method on our server-side. In the above request, we are asking the server only to send 2 properties.
Now run the application and navigate to route '/graphql' which opens the GraphQL tool called 'Bana Cake Pop' provided by HotChocolate for easy querying.

Create A Resolver Method To Fetch Multiple Records:

Now let's add a new resolver method in the 'Query' class that returns multiple records.
SchemaCore/Query.cs:
public List<Gadgets> AllGadgets()
{
  return new List<Gadgets>
  {
	new Gadgets{
	Id = 1,
	ProductName = "Samsung M30s",
	Brand = "Samsung",
	Cost = 15000,
	Type = "Mobile"
   },
   new Gadgets{
	Id = 2,
	ProductName = "Think Pad",
	Brand = "Lenovo",
	Cost = 75000,
	Type = "Laptop"
   }
  };
}
Now register this 'AllGadgets' resolver method as a field in the 'QueryObjectType'.
ObjectTypes/QueryObjectType.cs:
descriptor.Field(g => g.AllGadgets())
.Type<ListType<GadgetsObjectType>>().Name("AllGadgets");
  • Here 'ListType' GraphQL type that is equivalent to 'List'
In the next part, we will implement database integration, passing query parameters to filter data and GraphQL mutations.

Support Me!
Buy Me A Coffee PayPal Me

Wrapping Up:

Hopefully, I think this article delivered some useful information on implementing Hot Chocolate GraphQL in .Net5 Application. I love to have your feedback, suggestions, and better techniques in the comment section below.

Refer:

Follow Me:

Labels:

Comments

  1. UnknownApril 16, 2021 at 4:08 AM

    Hi Naveen, I've implemented a few graphql servers in dotnet, but I have always had trouble consuming it from a client i.e an app or website and I'd be interested to hear if you'd do a chapter exclusively on actually consuming it, ideally using Blazor
    Many thanks,
    Mani

    ReplyDelete
    Replies
    1. Naveen BommidiApril 16, 2021 at 12:47 PM

      Hi Mani

      I made blog using angular
      https://www.learmoreseekmore.com/2021/03/angular-application-consume-graphql-endpoint-using-apollo-angular-library.html

      I tried using blazor library like Strawberry Shake(Hot Chocolate GraphQL library)
      but currently i'm facing some issue with it.

      Delete

Post a Comment

Popular posts from this blog

Angular 14 Reactive Forms Example

In this article, we will explore the Angular(14) reactive forms with an example. Reactive Forms: Angular reactive forms support model-driven techniques to handle the form's input values. The reactive forms state is immutable, any form filed change creates a new state for the form. Reactive forms are built around observable streams, where form inputs and values are provided as streams of input values, which can be accessed synchronously. Some key notations that involve in reactive forms are like: FormControl - each input element in the form is 'FormControl'. The 'FormControl' tracks the value and validation status of form fields. FormGroup - Track the value and validate the state of the group of 'FormControl'. FormBuilder - Angular service which can be used to create the 'FormGroup' or FormControl instance quickly. Form Array - That can hold infinite form control, this helps to create dynamic forms. Create An Angular(14) Application: Let'
3 comments
Read more

.NET 7 Web API CRUD Using Entity Framework Core

In this article, we are going to implement a sample .NET 7 Web API CRUD using the Entity Framework Core. Web API: Web API is a framework for building HTTP services that can be accessed from any client like browser, mobile devices, and desktop apps. In simple terminology API(Application Programming Interface) means an interface module that contains programming functions that can be requested via HTTP calls either to fetch or update data for their respective clients. Some of the Key Characteristics of API: Supports HTTP verbs like 'GET', 'POST', 'PUT', 'DELETE', etc. Supports default responses like 'XML' and 'JSON'. Also can define custom responses. Supports self-hosting or individual hosting, so that all different kinds of apps can consume it. Authentication and Authorization are easy to implement. The ideal platform to build the REST full services. Install The SQL Server And SQL Management Studio: Let's install the SQL server on our l
3 comments
Read more

ReactJS(v18) JWT Authentication Using HTTP Only Cookie

In this article, we will implement the ReactJS application authentication using the HTTP-only cookie. HTTP Only Cookie: In a SPA(Single Page Application) Authentication JWT token either can be stored in browser 'LocalStorage' or in 'Cookie'. Storing the JWT token inside of the cookie then the cookie should be HTTP Only. The HTTP-ONly cookie nature is that it will be only accessible by the server application. Client apps like javascript-based apps can't access the HTTP-Only cookie. So if we use the authentication with HTTP-only JWT cookie then we no need to implement the custom logic like adding authorization header or storing token data, etc at our client application. Because once the user authenticated cookie will be automatically sent to the server by the browser on every API call. Authentication API: To authenticate our client application with JWT HTTP-only cookie, I developed a NetJS(which is a node) Mock API. Check the GitHub link and read the document on G
3 comments
Read more

.NET6 Web API CRUD Operation With Entity Framework Core

In this article, we are going to do a small demo on AspNetCore 6 Web API CRUD operations. What Is Web API: Web API is a framework for building HTTP services that can be accessed from any client like browser, mobile devices, desktop apps. In simple terminology API(Application Programming Interface) means an interface module that contains a programming function that can be requested via HTTP calls to save or fetch the data for their respective clients. Some of the key characteristics of API: Supports HTTP verbs like 'GET', 'POST', 'PUT', 'DELETE', etc. Supports default responses like 'XML' and 'JSON'. Also can define custom responses. Supports self-hosting or individual hosting, so that all different kinds of apps can consume it. Authentication and Authorization are easy to implement. The ideal platform to build REST full services. Create A .NET6 Web API Application: Let's create a .Net6 Web API sample application to accomplish our
6 comments
Read more

Angular 14 State Management CRUD Example With NgRx(14)

In this article, we are going to implement the Angular(14) state management CRUD example with NgRx(14) NgRx Store For State Management: In an angular application to share consistent data between multiple components, we use NgRx state management. Using NgRx state helps to avoid unwanted API calls, easy to maintain consistent data, etc. The main building blocks for the NgRx store are: Actions - NgRx actions represents event to trigger the reducers to save the data into the stores. Reducer - Reducer's pure function, which is used to create a new state on data change. Store - The store is the model or entity that holds the data. Selector - Selector to fetch the slices of data from the store to angular components. Effects - Effects deals with external network calls like API. The effect gets executed based the action performed Ngrx State Management flow: The angular component needs data for binding.  So angular component calls an action that is responsible for invoking the API call.  Aft
8 comments
Read more

Unit Testing Asp.NetCore Web API Using xUnit[.NET6]

In this article, we are going to write test cases to an Asp.NetCore Web API(.NET6) application using the xUnit. xUnit For .NET: The xUnit for .Net is a free, open-source, community-focused unit testing tool for .NET applications. By default .Net also provides a xUnit project template to implement test cases. Unit test cases build upon the 'AAA' formula that means 'Arrange', 'Act' and 'Assert' Arrange - Declaring variables, objects, instantiating mocks, etc. Act - Calling or invoking the method that needs to be tested. Assert - The assert ensures that code behaves as expected means yielding expected output. Create An API And Unit Test Projects: Let's create a .Net6 Web API and xUnit sample applications to accomplish our demo. We can use either Visual Studio 2022 or Visual Studio Code(using .NET CLI commands) to create any.Net6 application. For this demo, I'm using the 'Visual Studio Code'(using the .NET CLI command) editor. Create a fo
7 comments
Read more

Angular 14 Crud Example

In this article, we will implement CRUD operation in the Angular 14 application. Angular: Angular is a framework that can be used to build a single-page application. Angular applications are built with components that make our code simple and clean. Angular components compose of 3 files like TypeScript File(*.ts), Html File(*.html), CSS File(*.cs) Components typescript file and HTML file support 2-way binding which means data flow is bi-directional Component typescript file listens for all HTML events from the HTML file. Create Angular(14) Application: Let's create an Angular(14) application to begin our sample. Make sure to install the Angular CLI tool into our local machine because it provides easy CLI commands to play with the angular application. Command To Install Angular CLI npm install -g @angular/cli Run the below command to create the angular application. Command To Create Angular Application ng new name_of_your_app Note: While creating the app, you will see a noti
6 comments
Read more

Part-1 Angular JWT Authentication Using HTTP Only Cookie[Angular V13]

In this article, we are going to implement a sample angular application authentication using HTTP only cookie that contains a JWT token. HTTP Only JWT Cookie: In a SPA(Single Page Application) Authentication JWT token either can be stored in browser 'LocalStorage' or in 'Cookie'. Storing JWT token inside of the cookie then the cookie should be HTTP Only. The HTTP-Only cookie nature is that it will be only accessible by the server application. Client apps like javascript-based apps can't access the HTTP-Only cookie. So if we use authentication with HTTP only JWT cookie then we no need to implement custom logic like adding authorization header or storing token data, etc at our client application. Because once the user authenticated cookie will be automatically sent to the server by the browser on every API call. Authentication API: To implement JWT cookie authentication we need to set up an API. For that, I had created a mock authentication API(Using the NestJS Se
Post a Comment
Read more

ReactJS(v18) Authentication With JWT AccessToken And Refresh Token

In this article, we are going to do ReactJS(v18) application authentication using the JWT Access Token and Refresh Token. JSON Web Token(JWT): JSON Web Token is a digitally signed and secured token for user validation. The JWT is constructed with 3 important parts: Header Payload Signature Create ReactJS Application: Let's create a ReactJS application to accomplish our demo. npx create-react-app name-of-your-app Configure React Bootstrap Library: Let's install the React Bootstrap library npm install react-bootstrap bootstrap Now add the bootstrap CSS reference in 'index.js'. src/index.js: import 'bootstrap/dist/css/bootstrap.min.css' Create A React Component 'Layout': Let's add a React component like 'Layout' in 'components/shared' folders(new folders). src/components/shared/Layout.js: import Navbar from "react-bootstrap/Navbar"; import { Container } from "react-bootstrap"; import Nav from "react-boot
Post a Comment
Read more

A Small Guide On NestJS Queues

NestJS Application Queues helps to deal with application scaling and performance challenges. When To Use Queues?: API request that mostly involves in time taking operations like CPU bound operation, doing them synchronously which will result in thread blocking. So to avoid these issues, it is an appropriate way to make the CPU-bound operation separate background job.  In nestjs one of the best solutions for these kinds of tasks is to implement the Queues. For queueing mechanism in the nestjs application most recommended library is '@nestjs/bull'(Bull is nodejs queue library). The 'Bull' depends on Redis cache for data storage like a job. So in this queueing technique, we will create services like 'Producer' and 'Consumer'. The 'Producer' is used to push our jobs into the Redis stores. The consumer will read those jobs(eg: CPU Bound Operations) and process them. So by using this queues technique user requests processed very fastly because actually
9 comments
Read more