Skip to main content

Angular Material Drag And Drop UI Component(Part-3)


Precap:

Part-1:

Part-2:
Discussed on cdkDropListConnectedTo directive.
Discussed on cdkDropListData directive.
Discussed on transferArrayItem method.
Discussed on cdkDropListGroup directive.

cdkDropListEnterPredicate Directive:

A predicate is a function that returns boolean results either true or false. cdkDropListeEnterPredicate directive accepts a predicate as an input. So on dragging and dropping of an item into a container will be accepted based on predicate output, if the predicate returns true dropped item will be accepted by the container or if the predicate returns false dropped item will be rejected by the container. So by using the cdkDropListEnterPredicate directive, we can control the items that will be dragged and dropped onto the container.

Sample Example To Control Items Drag And Drop Using cdkDropListEnterPredicate Directive:

Let's first implement a sample of dragging and dropping off items between containers and later we will add cdkDropListEnteterPredicate directive.
src/app/cdkPredicate/cdk.predicate.sample.component.css:
.my-container {
    width: 400px;
    max-width: 100%;
    margin: 0 25px 25px 0;
    display: inline-block;
    vertical-align: top;
  }
  
  .my-list {
    border: solid 1px #ccc;
    min-height: 60px;
    background: white;
    border-radius: 4px;
    overflow: hidden;
    display: block;
  }
  
  .my-box {
    padding: 20px 10px;
    border-bottom: solid 1px #ccc;
    color: rgba(0, 0, 0, 0.87);
    display: flex;
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    box-sizing: border-box;
    cursor: move;
    background: white;
    font-size: 14px;
  }
  
  .cdk-drag-preview {
    box-sizing: border-box;
    border-radius: 4px;
    box-shadow: 0 5px 5px -3px rgba(0, 0, 0, 0.2),
                0 8px 10px 1px rgba(0, 0, 0, 0.14),
                0 3px 14px 2px rgba(0, 0, 0, 0.12);
  }
  
  .cdk-drag-placeholder {
    opacity: 0;
  }
  
  .cdk-drag-animating {
    transition: transform 250ms cubic-bezier(0, 0, 0.2, 1);
  }
  
  .my-box:last-child {
    border: none;
  }
  
  .my-list.cdk-drop-list-dragging .my-box:not(.cdk-drag-placeholder) {
    transition: transform 250ms cubic-bezier(0, 0, 0.2, 1);
  }
src/app/cdkPredicate/cdk.predicate.sample.component.html: 
<div class="my-container">
  <h2>All Students</h2>

  <div
    #allStudentsContainer="cdkDropList"
    cdkDropList
    [cdkDropListData]="allStudents"
    [cdkDropListConnectedTo]="[failedStudentsContainer]"
    class="my-list"
    (cdkDropListDropped)="drop($event)"
    
  >
    <div
      class="my-box"
      *ngFor="let student of allStudents"
      [cdkDragData]="student"
      cdkDrag
    >
      {{ student.Name }} -----> {{student.Result}}
    </div>
  </div>
</div>

<div class="my-container">
  <h2>Falied Students</h2>

  <div
    #failedStudentsContainer="cdkDropList"
    cdkDropList
    [cdkDropListData]="failedStudents"
    [cdkDropListConnectedTo]="[allStudentsContainer]"
    class="my-list"
    (cdkDropListDropped)="drop($event)"
    
  >
    <div
      class="my-box"
      *ngFor="let student of failedStudents"
      cdkDrag
      [cdkDragData]="student"
    >
      {{ student.Name }} ----> {{student.Result}}
    </div>
  </div>
</div>
src/app/cdkPredicate/cdk.predicate.sample.component.ts: 
  import { Component } from '@angular/core';
import {
  CdkDragDrop,
  moveItemInArray,
  transferArrayItem,
} from '@angular/cdk/drag-drop';

@Component({
  selector: 'cdk-predicate-sample',
  templateUrl: 'cdk.predicate.sample.component.html',
  styleUrls: ['cdk.predicate.sample.component.css'],
})
export class CdkPredicateSampleComponent {
  allStudents = [
    {
      Name: 'Naveen',
      Result: 'Failed'
    },
    {
      Name: 'Ramanajee',
      Result: 'Pass'
    },
    {
      Name: 'Rama Krishna',
      Result: 'Pass'
    },
    {
      Name: 'Gopi',
      Result: 'Pass'
    },
    {
      Name: 'Leela Narasimha',
      Result: 'Pass'
    },
    {
      Name: 'Hemanth Kumar',
      Result: 'Failed'
    }
  ];

  failedStudents = [];

  drop(event: CdkDragDrop<string[]>) {
    if (event.previousContainer === event.container) {
      moveItemInArray(
        event.container.data,
        event.previousIndex,
        event.currentIndex
      );
    } else {
      transferArrayItem(
        event.previousContainer.data,
        event.container.data,
        event.previousIndex,
        event.currentIndex
      );
    }
  }
}
src/app/app.component.html: 
<cdk-predicate-sample></cdk-predicate-sample>
src/app/app.module.ts: 
import { CdkPredicateSampleComponent } from './cdkPredicate/cdk.predicate.sample.component';

@NgModule({
  declarations: [
    CdkPredicateSampleComponent
  ]
})
export class AppModule {}
// code hidden for display purpose
Now run the application and output shows as below.

In this example, we have created two containers like 1st container contains all the students, 2nd container to contains failed student. Currently, sample implemented like any item can be dragged and dropped from one container to another without any restrictions.

Now let's add a restriction on 2nd container to accept only failed students. so to achieve this we can use cdkDropListEnterPredicate.

Let's start by creating a function that returns the boolean value and this function will be used as a predicate for the cdkDropListEnterPredicate.
src/app/cdkPredicate/cdk.predicate.sample.component.ts:
import { Component } from '@angular/core';
import {
  CdkDrag
} from '@angular/cdk/drag-drop';

@Component({
  selector: 'cdk-predicate-sample',
  templateUrl: 'cdk.predicate.sample.component.html',
  styleUrls: ['cdk.predicate.sample.component.css'],
})
export class CdkPredicateSampleComponent {
  
  onlyFailedStudents(item:CdkDrag){
     return item.data["Result"] === "Failed";
  }
  
  // code hidden for display purpose.
}
  • #L3 at this CdkDrag object type loaded from '@angular/cdk/drag-drop' package
  • #L13-L15 at these lines created method 'onlyFailedStudents', this method will be used as predicate value for the cdkDropListEnterPredicate directive. It has an input parameter of type 'CdkDrag' which gives all the information about the item on dragging. So in this example, this predicate or method returns a boolean value true for only items that of failed students. So this will restrict the dragging of all elements into the container that has cdkDropListEnterPredicate with 'onlyFailedStudents' as input predicate.
Now on 2nd container Html element decorate with cdkDropListEnterPredicate decorator with 'onlyFailedStudents' as input.This will make this 2nd container only accepts failed students on dragging.
src/app/cdkPredicate/cdk.predicate.sample.component.html:
<div class="my-container">
  <h2>All Students</h2>

  <div
    #allStudentsContainer="cdkDropList"
    cdkDropList
    [cdkDropListData]="allStudents"
    [cdkDropListConnectedTo]="[failedStudentsContainer]"
    class="my-list"
    (cdkDropListDropped)="drop($event)"
    
  >
    <div
      class="my-box"
      *ngFor="let student of allStudents"
      [cdkDragData]="student"
      cdkDrag
    >
      {{ student.Name }} -----> {{student.Result}}
    </div>
  </div>
</div>

<div class="my-container">
  <h2>Falied Students</h2>

  <div
    #failedStudentsContainer="cdkDropList"
    cdkDropList
    [cdkDropListData]="failedStudents"
    [cdkDropListConnectedTo]="[allStudentsContainer]"
    class="my-list"
    (cdkDropListDropped)="drop($event)"
    [cdkDropListEnterPredicate]="onlyFailedStudents"
  >
    <div
      class="my-box"
      *ngFor="let student of failedStudents"
      cdkDrag
      [cdkDragData]="student"
    >
      {{ student.Name }} ----> {{student.Result}}
    </div>
  </div>
</div>
#L34 at this line cdkDropListEnterPredicate added on 2nd container with 'onlyFailedStudent' predicate as input.

Now run the application and 2nd container only accepts failed students on drag and then output shows as below.

cdkDropListOrientation Directive:

cdkDropListOrientation directive defines items to render vertically or horizontally. By default, cdkDropList directive renders items vertically. So by using the cdkDropListOrientation directive, we can define explicitly to render items vertically or horizontally.

Example Using cdkDropListOrientation Directive:

Let's implement a sample application that renders items horizontally using the cdkDropListOrientation directive.
src/app/cdkOrientationSample/cdk.orientation.sample.css:
.my-list {
    width: 1000px;
    max-width: 100%;
    border: solid 1px #ccc;
    min-height: 60px;
    display: flex;
    flex-direction: row;
    background: white;
    border-radius: 4px;
    overflow: hidden;
  }
  
  .my-box {
    padding: 20px 10px;
    border-right: solid 1px #ccc;
    color: rgba(0, 0, 0, 0.87);
    display: flex;
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    box-sizing: border-box;
    cursor: move;
    background: white;
    font-size: 14px;
    flex-grow: 1;
    flex-basis: 0;
  }
  
  .cdk-drag-preview {
    box-sizing: border-box;
    border-radius: 4px;
    box-shadow: 0 5px 5px -3px rgba(0, 0, 0, 0.2),
                0 8px 10px 1px rgba(0, 0, 0, 0.14),
                0 3px 14px 2px rgba(0, 0, 0, 0.12);
  }
  
  .cdk-drag-placeholder {
    opacity: 0;
  }
  
  .cdk-drag-animating {
    transition: transform 250ms cubic-bezier(0, 0, 0.2, 1);
  }
  
  .my-box:last-child {
    border: none;
  }
  
  .my-list.cdk-drop-list-dragging .my-box:not(.cdk-drag-placeholder) {
    transition: transform 250ms cubic-bezier(0, 0, 0.2, 1);
  }
src/app/cdkOrientationSample/cdk.orientation.sample.ts: 
import { Component } from '@angular/core';
import { CdkDragDrop, moveItemInArray } from '@angular/cdk/drag-drop';

@Component({
    selector:'cdk-orientation',
    templateUrl:'cdk.orientation.sample.html',
    styleUrls:['cdk.orientation.sample.css']
})
export class CdkOrientationSample {

    fruits=[
        "Apple",
        "Grapes",
        "Banana",
        "Mango",
        "Pine apple"
    ];

    drop(event:CdkDragDrop<string>){
        moveItemInArray(this.fruits, event.previousIndex, event.currentIndex);
    }
}
src/app/cdkOrientationSample/cdk.orientation.sample.html: 
<div cdkDropList cdkDropListOrientation="horizontal" class="my-list" (cdkDropListDropped)="drop($event)">
    <div class="my-box" *ngFor="let fruit of fruits" cdkDrag>{{fruit}}</div>
</div>
#L1 at this line cdkDropListOrientation directive used and its value declared as 'horizontal'.

Now run the application, items rendered horizontally, and output shows as below.

Wrapping Up:

Hopefully, I think this article delivered some useful information on the Drag and Drop Angular Material CDK. I love to have your feedback, suggestions, and better techniques in the comment section below.

Refer:


Follow Me:

Labels:

Comments

  1. hiJune 10, 2021 at 2:53 AM

    Hi There,

    It's very nice explanation of drag and drop. Here my understanding is that instead of drag and drop with static data. Is it possible to drag and drop component and render at runtime?

    Thanks,
    Vinay

    ReplyDelete

Post a Comment

Popular posts from this blog

.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 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

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

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
6 comments
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
7 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
7 comments
Read more

Usage Of CancellationToken In Asp.Net Core Applications

When To Use CancellationToken?: In a web application request abortion or orphan, requests are quite common. On users disconnected by network interruption or navigating between multiple pages before proper response or closing of the browser, tabs make the request aborted or orphan. An orphan request can't deliver a response to the client, but it will execute all steps(like database calls, HTTP calls, etc) at the server. Complete execution of an orphan request at the server might not be a problem generally if at all requests need to work on time taking a job at the server in those cases might be nice to terminate the execution immediately. So CancellationToken can be used to terminate a request execution at the server immediately once the request is aborted or orphan. Here we are going to see some sample code snippets about implementing a CancellationToken for Entity FrameworkCore, Dapper ORM, and HttpClient calls in Asp.NetCore MVC application. Note: The sample codes I will show in
2 comments
Read more

Blazor WebAssembly Custom Authentication From Scratch

In this article, we are going to explore and implement custom authentication from the scratch. In this sample, we will use JWT authentication for user authentication. Main Building Blocks Of Blazor WebAssembly Authentication: The core concepts of blazor webassembly authentication are: AuthenticationStateProvider Service AuthorizeView Component Task<AuthenticationState> Cascading Property CascadingAuthenticationState Component AuthorizeRouteView Component AuthenticationStateProvider Service - this provider holds the authentication information about the login user. The 'GetAuthenticationStateAsync()' method in the Authentication state provider returns user AuthenticationState. The 'NotifyAuthenticationStateChaged()' to notify the latest user information within the components which using this AuthenticationStateProvider. AuthorizeView Component - displays different content depending on the user authorization state. This component uses the AuthenticationStateProvider
6 comments
Read more

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-Control Pragma Vary 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 fr
Post a Comment
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
4 comments
Read more