Is there any way to make a customizable URL with axios? For example, I've created an axios instance:
import axios from 'axios';
const instance = axios.create({
baseURL: 'localhost:8001/**test**/service/**test**/method' ,
});
export default instance;
Now I want to use this instance in many places in my project, but when I call this instance I'd like to change both **test** with params I pass to it.
Is that possible?
Make a function
function createAxios(string) {
return axios.create({baseUrl: `localhost:8001/${string}/service/**test**/method`})
}
So when you want it another place, just write
const instance = createAxios("test")
I am new to Angular 2 and TypeScript and I'm trying to follow best practices.
Instead of using a simple JavaScript model ({ }), I'm attempting to create a TypeScript class.
However, Angular 2 doesn't seem to like it.
My code is:
import { Component, Input } from "#angular/core";
#Component({
selector: "testWidget",
template: "<div>This is a test and {{model.param1}} is my param.</div>"
})
export class testWidget {
constructor(private model: Model) {}
}
class Model {
param1: string;
}
and I'm using it as:
import { testWidget} from "lib/testWidget";
#Component({
selector: "myComponent",
template: "<testWidget></testWidget>",
directives: [testWidget]
})
I'm getting an error from Angular:
EXCEPTION: Can't resolve all parameters for testWidget: (?).
So I thought, Model isn't defined yet... I'll move it to the top!
Except now I get the exception:
ORIGINAL EXCEPTION: No provider for Model!
How do I accomplish this??
Edit: Thanks to all for the answer. It led me to the right path.
In order to inject this into the constructor, I need to add it to the providers on the component.
This appears to work:
import { Component, Input } from "#angular/core";
class Model {
param1: string;
}
#Component({
selector: "testWidget",
template: "<div>This is a test and {{model.param1}} is my param.</div>",
providers: [Model]
})
export class testWidget {
constructor(private model: Model) {}
}
I'd try this:
Split your Model into a separate file called model.ts:
export class Model {
param1: string;
}
Import it into your component. This will give you the added benefit of being able to use it in other components:
Import { Model } from './model';
Initialize in the component:
export class testWidget {
public model: Model;
constructor(){
this.model = new Model();
this.model.param1 = "your string value here";
}
}
Access it appropriately in the html:
#Component({
selector: "testWidget",
template: "<div>This is a test and {{model.param1}} is my param.</div>"
})
I want to add to the answer a comment made by #PatMigliaccio because it's important to adapt to the latest tools and technologies:
If you are using angular-cli you can call ng g class model and it will generate it for you. model being replaced with whatever naming you desire.
The problem lies that you haven't added Model to either the bootstrap (which will make it a singleton), or to the providers array of your component definition:
#Component({
selector: "testWidget",
template: "<div>This is a test and {{param1}} is my param.</div>",
providers : [
Model
]
})
export class testWidget {
constructor(private model: Model) {}
}
And yes, you should define Model above the Component. But better would be to put it in his own file.
But if you want it to be just a class from which you can create multiple instances, you better just use new.
#Component({
selector: "testWidget",
template: "<div>This is a test and {{param1}} is my param.</div>"
})
export class testWidget {
private model: Model = new Model();
constructor() {}
}
export class Car {
id: number;
make: string;
model: string;
color: string;
year: Date;
constructor(car) {
{
this.id = car.id;
this.make = car.make || '';
this.model = car.model || '';
this.color = car.color || '';
this.year = new Date(car.year).getYear();
}
}
}
The || can become super useful for very complex data objects to default data that doesn't exist.
.
.
In your component.ts or service.ts file you can deserialize response data into the model:
// Import the car model
import { Car } from './car.model.ts';
// If single object
car = new Car(someObject);
// If array of cars
cars = someDataToDeserialize.map(c => new Car(c));
In your case you are having model on same page, but you have it declared after your Component class, so that's you need to use forwardRef to refer to Class. Don't prefer to do this, always have model object in separate file.
export class testWidget {
constructor(#Inject(forwardRef(() => Model)) private service: Model) {}
}
Additionally you have to change you view interpolation to refer to correct object
{{model?.param1}}
Better thing you should do is, you can have your Model Class define in different file & then import it as an when you require it by doing. Also have export before you class name, so that you can import it.
import { Model } from './model';
my code is
import { Component } from '#angular/core';
class model {
username : string;
password : string;
}
#Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
username : string;
password : string;
usermodel = new model();
login(){
if(this.usermodel.username == "admin"){
alert("hi");
}else{
alert("bye");
this.usermodel.username = "";
}
}
}
and the html goes like this :
<div class="login">
Usernmae : <input type="text" [(ngModel)]="usermodel.username"/>
Password : <input type="text" [(ngModel)]="usermodel.password"/>
<input type="button" value="Click Me" (click)="login()" />
</div>
You can use the angular-cli as the comments in #brendon's answer suggest.
You might also want to try:
ng g class modelsDirectoy/modelName --type=model
/* will create
src/app/modelsDirectoy
├── modelName.model.ts
├── ...
...
*/
Bear in mind:
ng g class !== ng g c
However, you can use ng g cl as shortcut depending on your angular-cli version.
I realize this is a somewhat older question, but I just wanted to point out that you've add the model variable to your test widget class incorrectly. If you need a Model variable, you shouldn't be trying to pass it in through the component constructor. You are only intended to pass services or other types of injectables that way. If you are instantiating your test widget inside of another component and need to pass a model object as, I would recommend using the angular core OnInit and Input/Output design patterns.
As an example, your code should really look something like this:
import { Component, Input, OnInit } from "#angular/core";
import { YourModelLoadingService } from "../yourModuleRootFolderPath/index"
class Model {
param1: string;
}
#Component({
selector: "testWidget",
template: "<div>This is a test and {{model.param1}} is my param.</div>",
providers: [ YourModelLoadingService ]
})
export class testWidget implements OnInit {
#Input() model: Model; //Use this if you want the parent component instantiating this
//one to be able to directly set the model's value
private _model: Model; //Use this if you only want the model to be private within
//the component along with a service to load the model's value
constructor(
private _yourModelLoadingService: YourModelLoadingService //This service should
//usually be provided at the module level, not the component level
) {}
ngOnInit() {
this.load();
}
private load() {
//add some code to make your component read only,
//possibly add a busy spinner on top of your view
//This is to avoid bugs as well as communicate to the user what's
//actually going on
//If using the Input model so the parent scope can set the contents of model,
//add code an event call back for when model gets set via the parent
//On event: now that loading is done, disable read only mode and your spinner
//if you added one
//If using the service to set the contents of model, add code that calls your
//service's functions that return the value of model
//After setting the value of model, disable read only mode and your spinner
//if you added one. Depending on if you leverage Observables, or other methods
//this may also be done in a callback
}
}
A class which is essentially just a struct/model should not be injected, because it means you can only have a single shared instanced of that class within the scope it was provided. In this case, that means a single instance of Model is created by the dependency injector every time testWidget is instantiated. If it were provided at the module level, you would only have a single instance shared among all components and services within that module.
Instead, you should be following standard Object Oriented practices and creating a private model variable as part of the class, and if you need to pass information into that model when you instantiate the instance, that should be handled by a service (injectable) provided by the parent module. This is how both dependency injection and communication is intended to be performed in angular.
Also, as some of the other mentioned, you should be declaring your model classes in a separate file and importing the class.
I would strongly recommend going back to the angular documentation reference and reviewing the basics pages on the various annotations and class types:
https://angular.io/guide/architecture
You should pay particular attention to the sections on Modules, Components and Services/Dependency Injection as these are essential to understanding how to use Angular on an architectural level. Angular is a very architecture heavy language because it is so high level. Separation of concerns, dependency injection factories and javascript versioning for browser comparability are mainly handled for you, but you have to use their application architecture correctly or you'll find things don't work as you expect.
create model.ts in your component directory as below
export module DataModel {
export interface DataObjectName {
propertyName: type;
}
export interface DataObjectAnother {
propertyName: type;
}
}
then in your component import above as,
import {DataModel} from './model';
export class YourComponent {
public DataObject: DataModel.DataObjectName;
}
your DataObject should have all the properties from DataObjectName.
How would I inject an addon service into other 'places'?
For example, if I install an addon that injects into controllers & components with the code below:
export default {
name: 'notification-messages-service',
initialize() {
let application = arguments[1] || arguments[0];
application.register('notification-messages:service', NotificationMessagesService);
['controller', 'component'].forEach(injectionTarget => {
application.inject(injectionTarget, 'notifications', 'notification-messages:service');
});
}};
How would I then inject the same service (the same singleton) into services & routes - my requirement is actually inject into a single service, services:messages?
I don't believe I can use
notifications: Ember.inject.service();
because in the addon the service is written as:
export default Ember.ArrayProxy.extend({...});
I can change the addon, of course, but my changes would be gone once the addon is updated.
Thanks for looking, N
notifications: Ember.inject.service('notification-messages');
should work
param for service is optional if name of service the same as property name, but it's bette always use it
P.S. code above for normal services
in you case code
['controller', 'component'].forEach(injectionTarget => {
application.inject(injectionTarget, 'notifications', 'notification-messages:service');
});
means that controllers/components just get new property notifications
So inside your controllers/components you can use
this.get('notifications')
I was able to inject the addon to my specific service by creating a new initialiser with the code below:
export default {
name: 'inject-ember-notification-service',
initialize: function(container, app) {
app.inject('services:message', 'notifications', 'notification-messages:service');
}
};
Fiendishly obtuse, ember!
Thanks to you all for your input.
Here's my use case:
I have an interface with 4 different implementations WorkflowA, WorkflowB, WorkflowC and WorkflowD.
export interface IWorkflow {
getQuestions();
validateQuestions();
getWorkflowSteps();
}
I have a WorkflowManager class that returns the appropriate workflow based on an input variable (Factory pattern?)
export class WorkflowManager {
workflow:IWorkflow;
getWorkflow(workflow){
switch (workflow) {
case 'workflowA':
return new workflowA();
case 'workflowB':
return new workflowB();
case 'workflowC':
return new workflowC();
case 'workflowD':
return new workflowD();
default:
throw new Error(`Unrecognized workflow: ${workflow}`);
}
}
}
I also have a component WorkflowComponent that gets loaded
Example:
/workflow=WorkflowA loads WorkflowComponent. The component then extracts the routeparam workflow and based on the value, it then passes it to the WorkflowManager which returns the appropriate workflow.
Here's a snippet of my component
#Component({
...
})
export class Workflow implements OnInit {
workflowInstance: IWorkflow;
constructor(
private route: ActivatedRoute,
private workflowManager: WorkflowManager,
) {
}
ngOnInit() {
this.route.params.subscribe(params => {
let regType: string = params['workflow'];
this.workflowInstance = this.workflowManager.getWorkflow(workflow);
});
}
}
But I don't like the idea of manually instantiating Workflow* classes. How can I improve this so I wire it using Angular2 supplied API so that it can be managed/injected in to other components?
Also in my current implementation, I will have to make ajax calls outside of Angular framework which I don't think is the best thing to do.
Any ideas on how to take advantage of the Angular framework and improve this?
One way is to inject an injector and acquire the workflow instance imperatively like:
#Injectable()
export class WorkflowManager {
constructor(private injector:Injector) {}
workflow:IWorkflow;
getWorkflow(workflow){
switch (workflow) {
case 'workflowA':
return this.injector.get(workflowA);
case 'workflowB':
return this.injector.get(workflowB);
case 'workflowC':
return this.injector.get(workflowC);
case 'workflowD':
return this.injector.get(workflowD);
default:
throw new Error(`Unrecognized workflow: ${workflow}`);
}
}
}
Alternatively you can inject workflowA, workflowB, workflowC, workflowA and just return the right one depending on the workflow but I think using the injector is a better fit for this use case.
Ensure you provide workflowA, workflowB, workflowC.
I am part of a Angular2 application (we use beta3) and the issue is the following:
Usually we have a component that uses some service that uses some rest call and the component displays the data. Great.
However we do have a page with more then 6 components all of them using the same REST call...(the backend returns data for ALL of them) and it doesn't make sense to call 6 times the REST for each component, also it will be weird if we do some client side caching.
Is there something available out of the box ? Or a Pattern to handle such case?
Thanks.
Just do it in a shared service. If you add it only in bootstrap(..., [OtherProviders, HTTP_PROVIDERS, MyService]) each component will get injected the same instance. Store the data in the service and every component can access it
export class MyComponent {
constructor(private dataService:MyService) {
dataService.getData().subscribe(data => { this.data = data; });
}
}
export class MyService {
getData() {
if(!this.data) {
return http.get(...).map(...).subscribe(data => { this.data = data;});
}
return this.data;
}
}
The #Günter's answer really makes sense!
I don't know your code is organized but observable can also be subscribed several times. To do that you need to make them "hot" using the share operator:
export class MyService {
dataObservable:Observable;
initDataObservable() {
this.dataObservable = http.get(...).map(...).share();
}
}
Without using the share operator, corresponding request will executed several times (one per subscribe).
You can notice that the request will be executed once one subscribe method is called on the observable.