Skip to main content

Split HTML And C# Code In Blazor Using Either Partial Class Or ComponentBase Class



By default Blazor component file consists of HTML code and C# code under the single file. For better coding standards we can split HTML code and C# code to separate files using concepts like:
  1. Partial Class
  2. ComponentBase Class

Create Sample Blazor Server Application:

Blazor Single Page Application comes with two types of templates like (1) Blazor Server, 
(2) Blazor Web Assembly. Let's create a Blazor Server templated sample application to understand to split the *.razor(Blazor file extension) files. 

Using Visual Studio 2019 using a rich user interface we can create Blazor Templated application very easily. But for this sample, I'm using .Net Core CLI(Command Line Interface) with Visual Studio Code IDE. Click to know how to use Visual Studio Code Editor for .Net Core applications.
.Net Core Blazor Server CLI Command:-

dotnet new BlazorServer -n Your_Application_Name
Blazor project preview:-
Open a command prompt whose path needs to be pointed to the Startup.cs file in our project(which application folder root path), then run the below .NET CLI command to start Blazor application.
CLI run Command:-

dotnet watch run
Application preview:-

Let's examine the Counter Component Code default sample Blazor component.
Pages/Counter.razor:
@page "/counter"

<h1>Counter</h1>

<p>Current count: @currentCount</p>

<button class="btn btn-primary" @onclick="IncrementCount">Click me</button>

@code {
    private int currentCount = 0;

    private void IncrementCount()
    {
        currentCount++;
    }
}
  • #L3 - #L7: These lines contain HTML code with model binding.
  • #L9 - #L16: These lines contain C# code.
  • By default Blazor component single file is a combination of HTML and C# code.
In upcoming steps, we going to split this Counter.razor to separate files using Partial Class and ComponentBase Class.

Why Split *.razor File?:

  1. Code separation is like a fundamental rule in programming.
  2. Separating the Html Code and C# makes the development of Blazor Component easy and maintainable.
  3. Makes C# Code Testable. 

Partial Class Implementation:

Partial Class is a feature of implementing a single class into multiple files. So now we will maintain the Html code in Counter.razor file and C# code in  Counter.razor.cs file. Counter.razor.cs file acts as a code-behind file for Counter.razor file. While writing class in Counter.razor.cs file we explicitly mention a partial keyword, but Counter.razor  Blazor file with Html Content, but .Net Compiler is good enough to read Counter.razor as a partial class, so on code compilation single Counter.cs file will be generated.
Let's create a Counter.razor.cs file and inject all c# code into it as below.
Pages/Counter.razor.cs:
namespace SplitFileSample.Pages
{
    public partial class Counter
    {
        private int currentCount = 0;

        private void IncrementCount()
        {
            currentCount++;
        }
    }
}
#L3: class declared with a partial keyword.
#L5 - #L10: c# code copied from Counter.razor file.

By chance, if we miss declaring partial keyword in class .Net compiler intelligent enough to notify us by failing the project compilation as below.

Visual Studio Code editor good enough to track the reference of Counter.razor.cs file members on Counter.razor file.
Finally Counter.razor file contains only HTML or Razor Code.
Pages/Counter.razor:
@page "/counter"

<h1>Counter</h1>

<p>Current count: @currentCount</p>

<button class="btn btn-primary" @onclick="IncrementCount">Click me</button>
That's all we have successfully used partial class implementation for code separation.

ComponentBase Class Implementation:

ComponentBase is a class that hooked up with all component life cycles of a Blazor Component. ComponentBase class is derived from the library Microsoft.AspNetCore.Components. This approach works with the class inheritance technique.

In this approach Counter.razor.cs file declares class like CounterBase.cs which inherits ComponentBase class. Finally Counter.razor file inherits CounterBase.cs class.
Let's implement the inheritance of ComponentBase class to CounterBase.cs file as below.
Pages/Counter.razor.cs:
using Microsoft.AspNetCore.Components;

namespace SplitFileSample.Pages
{
    public class CounterBase : ComponentBase
    {
        protected int currentCount = 0;

        protected void IncrementCount()
        {
            currentCount++;
        }
    }
}
  • #L1: To inherit ComponentBase class added the reference of the library name Microsoft.AspNetCore.Components
  • CounterBase class can override the life cycle methods that are inherited from ComponentBase class.
  • #L7, #L9: At these lines, we have used protected access specifiers, because of Counter.razor(inheritance in the upcoming steps) file inherits CounterBase. So the methods or properties which need to expose in Counter.razor file then their minimum access specifier should be protected from this we can draw a conclusion like we can't use private access specifier.
Reason to create a class name as CounterBase in Counter.razor.cs file - Class name can't be created as Counter. Because of Counter.razor file on compilation generates a partial class with the name Counter, in that case, if we create a class name as Counter in Counter.razor.cs file compiler throws an error like 'there is an existing partial class with name Counter, so please create your new class as partial'(this error simple violation of partial class rules). So we create a class name as CounterBase in Counter.razor.cs, here class name add tail with word 'Base' that is like a naming convention of representing like it is parent class for Counter.razor file.

Finally, inherit CounterBase class into Counter.razor file as below.
Pages/Counter.razor:
@inherits CounterBase
<h1>Counter</h1>

<p>Current count: @currentCount</p>

<button class="btn btn-primary" @onclick="IncrementCount">Click me</button>
At #L1 inherited CounterBase class.

That's it we completed ComponentBase class implementation as well.

Wrapping Up:

Hopefully, I think this article delivered some useful information about Partial Class and CounterBase class in Blazor Components. I love to have your feedback, suggestions, and better techniques in the comment section below.

Follow Me:

Comments

Popular posts from this blog

ASP.NET Core Web API Versioning

Introduction: An iteration and evolutionary changes of an ASP.NET Core Web API is handled by Versioning. Versioning of an API gives confidence to the clients which consumes API for a long time. Any changes or development of an API will be accessible using the new version and it won't cause issues to the clients consuming the old version of API.
When To Use Versioning:Any API response changes.Developing an API by implementing testing levels like 'Alpha', 'Beta', and 'RC' versions before releasing Production.Deprecating an API which means API going to be removed or upgraded by a version within a short period. Versioning Types:Query String VersioningUrl Path VersioningMedia Type Versioning API Version Nuget: To Configure versioning to AspNet Core Web API Microsoft provided a library(Microsoft.AspNetCore.Mvc.Versioning). So to use the versioning library please install NuGet below.
 Install-Package Microsoft.AspNetCore.Mvc.Versioning -version 4.0.0 Register API V…

GraphQL API Integration In Asp.Net Core Application

Introduction:
GraphQL 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 ASP.NET, Java, NestJs, etc and it isn't tied to any specific database or storage engine and is instead backed by your existing code and data.
How GraphQL API Different From Rest API: GraphQL exposes a single end-point or route for the entire application, regardless of its responses or actions.HTTP-POST is the only Http verb recommended by the GraphQL.The client applications (consumers of API) can give instructions to GraphQL API about what type of properties to be returned in the response. Building Blocks Of GraphQL API:The main building blocks of GraphQL API is Schemas and Types. A 'Schema' in GrpahQL API describes the functionality available to the clients connect to API. Schema mostly consists of GraphQL Object Types, Queries, Mutations, etc.Types likely to be called Grap…

Endpoint Routing In Asp.Net Core

How Routing Works In  Core 2.1 And Below Versions?: In Asp.Net Core routing is configured using app.UseRouter() or app.UseMvc() middleware. app.UseMvc(routes => { routes.MapRoute( name: "default", template: "{controller=Home}/{action=Index}/{id?}"); }); Here in Dotnet Core version 2.1 or below versions on the execution of route middleware request will be navigated appropriate controller matched to the route.

An operation or functionality which is dependent on route URL or route values and that need to be implemented before the execution of route middleware can be done by accessing the route path from the current request context as below
app.Use(async (context, next) => { if(context.Request.Path.Value.IndexOf("oldvehicle") != -1) { context.Response.Redirect("vehicle"); } else { await next(); } }); app.UseMvc(routes => { routes.MapRoute( name: "vehicleRoute", template: "vehicle", defaults:new { …

Blazor WebAssembly Dynamic Form Validation

Introduction: In Blazor WebAssembly(client-side framework) form validation can be done with Data Annotations. Using Data Annotations we can validate form either by default validation attributes or by creating custom validation attributes. Using this Data Annotation attribute we can dynamically add or remove validation on a specific field in a form.
Create Blazor WebAssembly Project: To create a Blazor WebAssembly template project need to install the latest version of VisualStudio 2019 for rich intelligence support or we can use VisualStudio code but less intelligence support from the editor. Click here to know about Blazor WebAssembly template creation. Blazor WebAssembly is in preview mode, not yet ready for production.
Create Razor Component: After creating a sample project using the Blazor WebAssembly template, in "Pages" folder add new Razor Component, name it as "UserForm.razor"
Add Route: In Blazor routing can be configured using @page  directive, and URL should b…

.NET Core MVC Application File Upload To Physical Location With Buffered Technique

Buffering Technique In File Upload:The server will use its Memory(RAM) or Disk Storage to save the files on receiving a file upload request from the client. Usage of Memory(RAM) or Disk depends on the number of file requests and the size of the file. Any single buffered file exceeding 64KB is moved from Memory to a temp file on disk. If an application receives heavy traffic of uploading files there might be a chance of out of Disk or RAM memory which leads to crash application. So this Buffer technique used for small files uploading. In the following article, we create a sample for the file uploading using .NET Core MVC application.
Create The .NET Core MVC Project: Let's create a .NET Core MVC project, here for this sample I'm using Visual Studio Code as below.  Check the link to use the Visual Studio Code for .NET Core Application.
IFormFile: Microsoft.AspNetCore.Http.IFormFile used for file upload with buffered technique. On uploading files from the client, then the entire …

Ionic Picker Sample Code In Angular

Introduction: Ionic Picker(ion-picker) is a popup slides up from the bottom of the device screen, which contains rows with selectable column separated items.
The main building block of ion-picker as follows: PickerControllerPickerOptions PickerController: PickerController object helps in creating an ion-picker overlay. create(opts?: Opts): Promise<Overlay> PickerController create method helps in create the picker overlay with the picker options
PickerOptions: PickerOptions is a configuration object used by PickerController to display ion-picker.
Single Column Ionic Picker: single.item.picker.ts: import { Component } from "@angular/core"; import { PickerController } from "@ionic/angular"; import { PickerOptions } from "@ionic/core"; @Component({ selector: "single-column-picker", templateUrl:"single.item.picker.html" }) export class SingleItemPicker { animals: string[] = ["Tiger", "Lion", "Elephant"…

Asp.Net Core MVC Form Validation Techniques

Introduction: Form validations in any applications are like assures that a valid data is storing on servers. All programing frameworks have their own individual implementations for form validations. In Dotnet Core MVC application server-side validations carried on by the models with the help of Data Annotations and the client-side validations carried by the plugin jQuery Unobtrusive Validation. jQuery Unobtrusive Validation is a custom library developed by Microsoft based on the popular library jQuery Validate.
In this article, we are going to learn how the model validation and client-side validation works in Asp.Net Core MVC Application with sample examples.
Getting Started: Let's create an Asp.Net Core MVC application project using preferred editors like Microsoft Visual Studio or Microsoft Visual Studio Code. Here I'm using Visual Studio.
Let's create an MVC controller and name it as 'PersonController.cs' and add an action method as below.
PersonController.cs: us…

NestJS API CRUD Operations With MongoDB

Introduction: NestJS is a framework used to develop server-side applications. NestJS built on top of Node.js frameworks like Express. It is a combination of Progressive Javascript, Object-Oriented Programming, Functional Programming, and Functional Reactive Programming.
Nest CLI Installation: Using Nest CLI we are able to generate the NestJS starter project with the default template. To install Nest CLI globally over our system open command prompt and run the command
npm i -g @nestjs/cli Now create a sample project by using Nest CLI command  nest new your_project_name package.json: Now open the package.json file from the sample application created, you can observe few properties like "scripts", "dependencies", and "devDependencies".
"dependencies" contains all plugins to be installed and used them to run the application.
"devDependencies" contain all plugins to be installed and used them at the time of application development.
"scrip…

Blazor Server CRUD Operations

Introduction: Blazor Server is a web framework to develop server-side single-page applications. Blazor is made up of components with the combinations on C#, Html, CSS.  Blazor Server is production-ready from the .Net Core 3.0.  Blazor Server Working Mechanism:Blazor Server is a very light-weight web development framework. In Blazor Server, not all code gets downloaded to the client browsers. Blazor Server made of components these components can be a block of code or page with respective navigation. Blazor server application communicates with the server with a SignalR background connection which is inbuilt functionality. Application click,  form submission, change events, application page navigation every operation is carried out by the SignalR connection by communicating with the server. Blazor updates the Html DOM very gently on every data update without any overhead. Blazor Server application maintains a nice intelligent tree structure to update the required information or changed …

How Response Caching Works In Asp.Net Core

What Is Response Caching?: Response Caching means storing of response output and using stored response until it's under it's the expiration time. Response Caching approach cuts down some requests to the server and also reduces some workload on the server. Response Caching Headers: Response Caching carried out by the few Http based headers information between client and server.
Main Response Caching Headers are like below
Cache-ControlPragmaVary Cache-Control Header: Cache-Control header is the main header type for the response caching. Cache-Control will be decorated with the following directives. public - this directive indicates any cache may store the response.private - this directive allows to store response with respect to a single user and can't be stored with shared cache stores.max-age - this directive represents a time to hold a response in the cache.no-cache - this directive represents no storing of response and always fetch the fresh response from serverno-store…