Skip to main content

Angular Material Drag And Drop UI Component(Part-2)


Part -1 Precap:

Introduction to drag and drop Angular Material CDK.
Discussed cdkDrag Directive
Discussed cdkDropList Directive
Discussed the cdkDropListDropped event.

cdkDropListConnectedTo Directive:

cdkDropListConnectedTo directive helps to drag and drop of items between the multiple cdkDropList instances. The communication between two different cdkDropList established either by assigning the cdkDropList template variable to the cdkDropListConnectedTo directive or by assigning the cdkDropList Html element id value to cdkDropListConnectedTo directive.

cdkDropListData Directive:

cdkDropListData Directive takes input like a component object that will render as Html Element items in cdkDropList instance. By assigning a component model object to cdkDropListData, makes our data to available in CDK drag and drop instance for sorting the data on each drag and drop of elements.

transferArrayItem method:

  • transferArrayItem method gets loaded from '@angular/cdk/drag-drop'. This method uses the component model data that was assigned to the cdkDropListData directive and then sort that data.
  • By using the cdkDropListConnectedTo directive will transfer data from one cdkDropList instance to another cdkDropList instance which means moving an item from one model object to another model object. 
  • By using the transferArrayItem method we can sort the data of both source and destination cdkDroList instances model objects.

Sample Using cdkDropListConnectedTo Directive:

Let's implement a sample example of drag and drop of data from one instance to another instance using the cdkDropListConnectedTo directive.

Let's add the CSS for our sample as below.
src/app/groupDragDrop/group.drag.drop.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);
  }
Now let's add model objects in the component class follows
src/app/groupDragDrop/group.drag.drop.component.ts:
import {Component} from '@angular/core';
import { moveItemInArray, transferArrayItem, CdkDragDrop } from '@angular/cdk/drag-drop';

@Component({
    selector:'group-drag-drop',
    templateUrl:'group.drag.drop.component.html',
    styleUrls:['group.drag.drop.component.css']
})
export class GroupDragDropComponent {
    squad = [
        "Rohit Sharma",
        "Virat Kohli",
        "Ms Dhoni",
        "Shikar Dhawan",
        "Ambati Rayudu",
        "Suresh Raina"
    ];

    selectedPlayers =[];

    drop(event:CdkDragDrop<string[]>){
        console.log(event);
    }
}
  • #L2 at this line loading CdkDragDrop, moveItemArray, tranferArrayItem from '@angular/cdk/drag-drop' package.
  • #L10-L17 at these lines initialized array of strings, this array object will be assigned to the cdkDropListData directive of one of the instances of cdkDropList.
  • #L19 at this initialized empty array object, this object will be assigned to the cdkDropListData directive of another cdkDrpList. Here the main idea is we going to drag and drop data from either 'squad' object to 'selectedPlayers' object or 'selectedPlayers' object to 'squad' object.
  • #L21-L23 at these line component method 'drop' created this method will be registered with cdkDropListDropped event. Currently, no logic is implemented inside of this method, in upcoming steps we will update this method logic.
Now let's add Html code as follows.
src/app/groupDragDrop/group.drag.drop.component.html:
<div class="my-container">
   <h2>Full Squad</h2>

   <div
    cdkDropList
    #fullSquadList = "cdkDropList"
    [cdkDropListData]="squad"
    [cdkDropListConnectedTo]="[selectedTeamList]"
    class="my-list"
    (cdkDropListDropped)="drop($event)">
    <div class="my-box" *ngFor="let player of squad" cdkDrag>{{player}}</div>
   </div>
</div>

<div class="my-container">
    <h2>Selected Team</h2>
    <div
     cdkDropList
     #selectedTeamList="cdkDropList"
     [cdkDropListData]="selectedPlayers"
     [cdkDropListConnectedTo]="[fullSquadList]"
     class="my-list"
     (cdkDropListDropped)="drop($event)">
      <div class="my-box" *ngFor="let player of selectedPlayers" cdkDrag>
         {{player}}
      </div>
    </div>
</div>
  • Here we can observe 2 separate containers of div elements declared.
  • #L5&L18 at these lines div element of each container decorated with cdkDropList directive.
  • #L10&L23 at these lines div element configured with cdkDropListDropped event and to this event, we configured 'drop' method.
  • #L6 at this line '#fullSquadList' is a template variable that will represent one of the containers. This template variable will be used as input value to 'cdkDropListConnectedTo' directive of another container to establish communication between containers.
  • #L19 at this line '#selectedTeamList' is a template variable that will represent one of the containers. This template variable will be used as the input value to 'cdkDropListConnectedTo' directive of another container to establish communication between the container.
  • #L7 at this line cdkDropListData directive declared this will take input data from the component object. Here we assign 'squad'(array of strings object). By assigning data to cdkDropListData will help us to fetch the data object at the cdkDropListDropped event.
  • #L20 at this line cdkDropListData directive declares and it takes input as 'selectedPlayers'(empty array object to which data get populated on drag and drop the element from the first container).
  • #L8&L21 at these lines cdkDropListConnectedTo directive declared, which takes input as angular template variables of other containers to make communication between those containers.
  • #L11&L24 at these lines cdkDrag directive added to div element to make the draggable elements.
Now let's add component Html tag on the app component Html file as below.
src/app/app.component.html:
<group-drag-drop></group-drag-drop>
Now let's import our component on to app module file as below.
src/app/app.module.ts:
import { GroupDragDropComponent } from './groupDragDrop/group.drag.drop.component';

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

Now if we try to drag and drop items from container1 to container2 will not work it will get refershed to initial state. If we try to drag and drop items by sorting items with in the containers also will not work

The reason for this is we haven't sorted the data objects like 'squad', 'selectedPlayers' in our component. This sorting of data will be implemented in 'drop' method in our component in upcoming steps.
Let's start fixing the sorting of items in its own container.
src/app/groupDragDrop/group.drag.drop.component.ts:
drop(event:CdkDragDrop<string[]>){
	console.log(event);
	if(event.previousContainer === event.container){
		 moveItemInArray(event.container.data, event.previousIndex, event.currentIndex)
	}
}
  • #L3 at this line we can observe 'previousContainer', 'container' props from CdkDragDrop instance. 
  • Each cdkDropList instance represents a container. 
  • So on dragging and dropping of an element in cdkDropList instance, the cdkDropListDropped event gets invoked in which each container information will be automatically populated as event information of drag and drop. 
  • Since we want to fix the issue of sorting or drag and drop of the element within the container(cdkDropList instance). 
  • So here we check for 'previousContainer' matches with the container(element dropped current container). If matches drag and drop implemented inside of the container. Then using 'moveItemArray' we will sort the component data object. 
  • If you carefully observe we are not accessing the component object directly but we are using 'event.container.data'. If you recall we assigned cdkDropListData directive in HTML assigned with component data, the same data will be passed to container and can be accessed as 'event.container.data'.
  • Finally, using component data and previous index and current index data will be sorted as per drag and drop of an element.
Now run the application and outputs shows as below.
Now within the container 1 drag, the 1st element to 3rd position and the output shows as below.
Now we need to fix the issue drag and drop of items between the containers.
src/app/groupDragDrop/group.drag.drop.component.ts:
drop(event:CdkDragDrop<string[]>){
	console.log(event);
	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
		);
	}
}
#L6-L11 at these lines 'transferArrayItem' method used to sort the data drag and dropped between two or more containers(cdkDropList instances). It takes 'event.previousContainer.data'(represents source container data from where the element will be dragged), 'event.container.data'(represents the destination container data from where the element will be dropped).

Now run the application and output shows as below.
After dragging and dropping a few items on container2 and then output shows as below.

cdkDropListGroup Directive:

cdkDropListGroup directive is another way of grouping the cdkDropList instances. This approach is the best technique for grouping the N-number of cdkDropList instances dynamically.

Example Using cdkDropListGroup Directive:

src/app/groupDragDrop/dynamic.group.component.ts:
import { Component } from '@angular/core';
import {CdkDragDrop, moveItemInArray, transferArrayItem, DragDrop} from '@angular/cdk/drag-drop';

@Component({
    selector:'dynamic-group',
    templateUrl:'dynamic.group.component.html',
    styleUrls:['dynamic.group.component.css']
})
export class DynamicGroupComponent {
    data = [{
        Catergory:"Fruits",
        Items:[
            "Mango",
            "Apple",
            "Banana",
            "WaterMelon",
            "Sapota",
        ]
    },{
        Catergory:"Juice",
        Items:[
            "Mango Juice",
            "Apple Juice",
            "Banana Juice",
            "WaterMelon Juice",
            "Sapota Juice",
        ]
    }];
    drop(events:CdkDragDrop<string[]>){
        if(events.previousContainer === events.container){
            moveItemInArray(events.container.data, events.previousIndex, events.currentIndex);
        }else{
            transferArrayItem(events.previousContainer.data, events.container.data, events.previousIndex,events.currentIndex);
        }
    }
}
#L10-L28 at these lines collection objects assigned to the 'data' variable. Each object in the collection represents a cdkDropList instance and these instances are grouped by cdkDropListGroup directive.

Styling for this new component the same as the above example we discussed so copy those styles to this component CSS file.

Now let's add HTML wit cdkDropListGroup directive which contains dynamically created cdkDropList instances as below
src/app/groupDragDrop/dynamic.group.component.html:
<div cdkDropListGroup>
    <div class="my-container" *ngFor="let d of data">
        <h2>{{d.Catergory}}</h2>
     
        <div
         cdkDropList
         [cdkDropListData]="d.Items"
         class="my-list"
         (cdkDropListDropped)="drop($event)">
         <div class="my-box" *ngFor="let item of d.Items" cdkDrag>{{item}}</div>
        </div>
     </div>
</div>
  • #L1 at this line cdkDropListGroup directive decorated to group the cdkDropList instances dynamically.
  • #L2 at this line by looping 'data' object cdkDropList instances created dynamically.
Now add the new component Html tag on to the app component HTML as below
src/app/app.component.html:
<dynamic-group></dynamic-group>
Now import the new component on to the app module file as below.
src/app/app.module.ts:
import { DynamicGroupComponent } from './groupDragDrop/dynamic.group.component';

@NgModule({
  declarations: [
    DynamicGroupComponent
  ],
})
export class AppModule {}
// code hidden for display purpose
Now run the application and output shows as below.
After swapping items by drag and drop then the 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:

Comments

Popular posts from this blog

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 { …

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…

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…

.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…

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…

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 …

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…

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…