Angular 2 Beta Faces Issues with Loading Dynamic Routes

Question

Angular 2 Beta Faces Issues with Loading Dynamic Routes

I am currently working on dynamically loading routes for the @RouteConfig from a service that fetches data in JSON format.

[
  { "path" : "/about" , "name" : "About" , "component" : "AboutComponent" },
  { "path" : "/contact" , "name" : "Contact" , "component" : "ContactComponent" }
]

Below is the snippet of code I use to populate the RouteDefinition Array,

for (let i = 0; i < data.length; i++) {
  this.routeConfigArray.push({
    'path': data[i].path,
    'name': data[i].name,
    'component': data[i].component
  });
  this._router.config(this.routeConfigArray); 
}

The issue arises when trying to set the component property with a string value, which should actually be a Classname. How can I convert the string containing classname into a class?

I have also attempted to use the Route class like this:

this.routeConfigArray.push(new Route({path: data[i].path, name: data[i].name, component:data[i].component}));

However, I keep encountering this Console Error:

Component for route "/about" is not defined, or is not a class. I have tried different approaches such as using
eval("new "+data[i].component+"()); || new window[data[i].component] .

I am facing difficulties in resolving this issue and would appreciate any guidance to solve it.

angularjs routes typescript angular angular2-routing

Answer 1

Answer №1

When TypeScript compiles imports into JavaScript, it follows a specific syntax. To use eval(), you can experiment with an approach like the one below, even though it may not be effective if TypeScript compiles differently. It's interesting to see if this method proves to be successful anyway :)

for (let i = 0; i < data.length; i++) {
  this.routeConfigArray.push({ //routeConfigArray : RouteDefinition
    path: data[i].path,
    name: data[i].name,
    component: getComponent(data[i].component)
  });
  this._router.config(this.routeConfigArray);   
}

function getComponent(comp : string) : Function {
    //convert camelCase to underscore notation
    let component : string = comp;
    component = component[0].toLowerCase() + component.slice(1);
    component = component.replace(/([A-Z])/g, function(match) {
        return '_' + match.toLowerCase();
    });
    component += '_1';
    return eval(component[comp])
}

ADDENDUM

If you find success in using an AsyncRoute as part of your solution, that's commendable progress. Perhaps organizing the pages in a particular manner could allow you to extract the resource location from the path. While not necessary, you could potentially create an algorithm to derive the resource string from the path string (e.g. from /about to ./app/about/about.component). This might be a future enhancement idea.

You can consider implementing something similar to the following code snippet using the AsyncRoute:

Warning: Unverified code below

let routes: any[] = [
    { "path": "/about", "name": "About", "component": "AboutComponent", "route": "/About", "resource": "./app/about/about.component" },
    { "path": "/contact", "name": "Contact", "component": "ContactComponent", "route": "/Contact", "resource": "./app/contact/contact.component" }
];

routes.forEach((route: any) => {
    this.routeConfigArray.push(
        new AsyncRoute({
            path: route.path,
            loader: () => System.import(route.resource).then(m => m[route.component]),
            name: route.name
        })
    );
});

this._router.config(this.routeConfigArray);

Answer 2

When TypeScript compiles imports into JavaScript, it follows a specific syntax. To use eval(), you can experiment with an approach like the one below, even though it may not be effective if TypeScript compiles differently. It's interesting to see if this method proves to be successful anyway :)

for (let i = 0; i < data.length; i++) {
  this.routeConfigArray.push({ //routeConfigArray : RouteDefinition
    path: data[i].path,
    name: data[i].name,
    component: getComponent(data[i].component)
  });
  this._router.config(this.routeConfigArray);   
}

function getComponent(comp : string) : Function {
    //convert camelCase to underscore notation
    let component : string = comp;
    component = component[0].toLowerCase() + component.slice(1);
    component = component.replace(/([A-Z])/g, function(match) {
        return '_' + match.toLowerCase();
    });
    component += '_1';
    return eval(component[comp])
}

ADDENDUM

If you find success in using an AsyncRoute as part of your solution, that's commendable progress. Perhaps organizing the pages in a particular manner could allow you to extract the resource location from the path. While not necessary, you could potentially create an algorithm to derive the resource string from the path string (e.g. from /about to ./app/about/about.component). This might be a future enhancement idea.

You can consider implementing something similar to the following code snippet using the AsyncRoute:

Warning: Unverified code below

let routes: any[] = [
    { "path": "/about", "name": "About", "component": "AboutComponent", "route": "/About", "resource": "./app/about/about.component" },
    { "path": "/contact", "name": "Contact", "component": "ContactComponent", "route": "/Contact", "resource": "./app/contact/contact.component" }
];

routes.forEach((route: any) => {
    this.routeConfigArray.push(
        new AsyncRoute({
            path: route.path,
            loader: () => System.import(route.resource).then(m => m[route.component]),
            name: route.name
        })
    );
});

this._router.config(this.routeConfigArray);

Answer 3

Answer №2

Hey @PierreDuc, you're a rockstar! I was just dabbling with regex to create a similar function, and here are some tweaks I noticed to make it work smoothly...

for (let i = 0; i < data.length; i++) {
  this.routeConfigArray.push({ //routeConfigArray : RouteDefinition
    'path': data[i].path,
    'name': data[i].name,
    'component': getComponent(data[i].component).constructor
  });
  this._router.config(this.routeConfigArray);   
}

function getComponent(comp : string) : Function {
    //convert camelCase to underscore notation
    let component : string = comp;
    component = component[0].toLowerCase() + component.slice(1);
    component = component.replace(/([A-Z])/g, function(match) {
        return '_' + match.toLowerCase();
    });
    component += '_1.';
    return eval("new "+component+comp+"()")
}

Big thanks once again buddy, everything's up and running now! Phew, what a relief!

Answer 4

Hey @PierreDuc, you're a rockstar! I was just dabbling with regex to create a similar function, and here are some tweaks I noticed to make it work smoothly...

for (let i = 0; i < data.length; i++) {
  this.routeConfigArray.push({ //routeConfigArray : RouteDefinition
    'path': data[i].path,
    'name': data[i].name,
    'component': getComponent(data[i].component).constructor
  });
  this._router.config(this.routeConfigArray);   
}

function getComponent(comp : string) : Function {
    //convert camelCase to underscore notation
    let component : string = comp;
    component = component[0].toLowerCase() + component.slice(1);
    component = component.replace(/([A-Z])/g, function(match) {
        return '_' + match.toLowerCase();
    });
    component += '_1.';
    return eval("new "+component+comp+"()")
}

Big thanks once again buddy, everything's up and running now! Phew, what a relief!

Answer 5

Answer №3

Consider a different approach suggested by @Pierre and @Pratik that involves using a method to retrieve the name of classes:

Object.prototype.getName = function() { 
  var funcNameRegex = /function (.{1,})\(/;
  var results = (funcNameRegex).exec((this).constructor.toString());
  return (results && results.length > 1) ? results[1] : "";
};

In your component, you can set up routes dynamically like this:

ngOnInit() {
  this.routes = [
    {
      path: '/test', component: 'OtherComponent', name: 'Test'
    }
  ];
  this.configureRoutes(this.routes);
  this.router.config( this.routes);
}

configureRoutes(routes) {
  var potentialComponents = [ OtherComponent ];
  routes.forEach((route) => {
    route.component = potentialComponents.find((component) => {
      return component.name === route.component;
    });
  });
}

This method requires knowing in advance the potential components involved in routing.

Check out this plunkr for a demo: https://plnkr.co/edit/KKVagp?p=preview.

For more information, refer to this question:

How do I get the name of an object's type in JavaScript?

Answer 6

Consider a different approach suggested by @Pierre and @Pratik that involves using a method to retrieve the name of classes:

Object.prototype.getName = function() { 
  var funcNameRegex = /function (.{1,})\(/;
  var results = (funcNameRegex).exec((this).constructor.toString());
  return (results && results.length > 1) ? results[1] : "";
};

In your component, you can set up routes dynamically like this:

ngOnInit() {
  this.routes = [
    {
      path: '/test', component: 'OtherComponent', name: 'Test'
    }
  ];
  this.configureRoutes(this.routes);
  this.router.config( this.routes);
}

configureRoutes(routes) {
  var potentialComponents = [ OtherComponent ];
  routes.forEach((route) => {
    route.component = potentialComponents.find((component) => {
      return component.name === route.component;
    });
  });
}

This method requires knowing in advance the potential components involved in routing.

Check out this plunkr for a demo: https://plnkr.co/edit/KKVagp?p=preview.

For more information, refer to this question:

How do I get the name of an object's type in JavaScript?

Answer 7

Answer №4

Update to the scenario mentioned above : The process involves dynamically loading routes on the user interface. To enable this functionality, I initially have to specify it in my AppComponent.

import {AboutComponent} from '/path';
import {ContactComponent} from '/path';

//and then either include it in a directive or mention The component Name some place in the code

However, this defeats the purpose of 'Dynamic Loading' as I would need to know which components are requested and cannot lazy load them. For instance, if I were to repeat this for 500 components, I would have to preload them all and then select which ones should be loaded based on a JSON file.

Solution (Completed And Tested) ==> I have found a way to make the loading process truly dynamic without specifying the components in any import statement or directive. This allows for lazy loading.

How By utilizing the AsyncRoute Class.

Here's the updated JSON structure:
//"route" is mapped to [routerLink]="['/Home']" & "resource" contains the actual path of the component

[
  { "path" : "/about" , "name" : "About" , "component" : "AboutComponent", "route": "/About" , "resource" : "./app/about/about.component" },
  { "path" : "/contact" , "name" : "Contact" , "component" : "ContactComponent", "route": "/About" , "resource" : "./app/about/about.component" },
  { "path" : "/blog" , "name" : "Blog" , "component" : "AboutComponent", "route": "/About" , "resource" : "./app/about/about.component" },
  { "path" : "/news" , "name" : "News" , "component" : "AboutComponent", "route": "/About" , "resource" : "./app/about/about.component" }
]

In the code snippet below, I fetch this JSON data, add it to the routeConfigArray which consists of RouteDefinition[], and configure the Router by calling .config(routeConfigArray)

let routes : any[] = data; // contains the JSON data in an array

routes.forEach((route : any) => {
        this.routeConfigArray.push(
            new AsyncRoute({
                path : route.path,
                loader : () => System.import(route.resource).then(m => m[route.component]),
                name : route.name
            })
        );
    });

this._router.config(this.routeConfigArray);

And that's how it operates!!!

Answer 8

Update to the scenario mentioned above : The process involves dynamically loading routes on the user interface. To enable this functionality, I initially have to specify it in my AppComponent.

import {AboutComponent} from '/path';
import {ContactComponent} from '/path';

//and then either include it in a directive or mention The component Name some place in the code

However, this defeats the purpose of 'Dynamic Loading' as I would need to know which components are requested and cannot lazy load them. For instance, if I were to repeat this for 500 components, I would have to preload them all and then select which ones should be loaded based on a JSON file.

Solution (Completed And Tested) ==> I have found a way to make the loading process truly dynamic without specifying the components in any import statement or directive. This allows for lazy loading.

How By utilizing the AsyncRoute Class.

Here's the updated JSON structure:
//"route" is mapped to [routerLink]="['/Home']" & "resource" contains the actual path of the component

[
  { "path" : "/about" , "name" : "About" , "component" : "AboutComponent", "route": "/About" , "resource" : "./app/about/about.component" },
  { "path" : "/contact" , "name" : "Contact" , "component" : "ContactComponent", "route": "/About" , "resource" : "./app/about/about.component" },
  { "path" : "/blog" , "name" : "Blog" , "component" : "AboutComponent", "route": "/About" , "resource" : "./app/about/about.component" },
  { "path" : "/news" , "name" : "News" , "component" : "AboutComponent", "route": "/About" , "resource" : "./app/about/about.component" }
]

In the code snippet below, I fetch this JSON data, add it to the routeConfigArray which consists of RouteDefinition[], and configure the Router by calling .config(routeConfigArray)

let routes : any[] = data; // contains the JSON data in an array

routes.forEach((route : any) => {
        this.routeConfigArray.push(
            new AsyncRoute({
                path : route.path,
                loader : () => System.import(route.resource).then(m => m[route.component]),
                name : route.name
            })
        );
    });

this._router.config(this.routeConfigArray);

And that's how it operates!!!

Angular 2 Beta Faces Issues with Loading Dynamic Routes

Answer №1

Answer №2

Answer №3

Answer №4

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