Change a single route parameter on the current route in Angular 2

Question

Is it possible to change a single route parameter in the current route, while keeping all the other parameters? This is for use in a paging component, which will route to a new

Answer 1

It's quite easy. Let's say we have a method in our ListComponent that changes the page and keeps all other parameters intact (like search related parameters - can't change the page and forget we were searching for something:):

page (page) {
    this.list.page = page;
    this._router.navigate([this.list.route, _.assign(this._params.params, { page: page })]);
    this.update(); // Update your list of items here
}

I used Underscore to assign a page parameter to the existing map of parameters from my private, injected RouteParams object. That map is updated on navigate so we're all good, just remember you can't change it directly, it's imutable.

Here is my implementation of a list of articles along with a pagination component used as a directive to provide pagination:

ArticleListComponent:

@Component({
    selector: 'articles',
    templateUrl: './article/list/index.html',
    directives: [PaginationComponent],
    providers: [ArticleService]
})
export class ArticleListComponent implements OnInit {
    list: ArticleList = new ArticleList;

    private _urlSearchParams: URLSearchParams = new URLSearchParams;

    constructor (
        private _article: ArticleService,
        private _router: Router,
        private _params: RouteParams,
        private _observable: ObservableUtilities
    ) {}

    update () {
        this._observable.subscribe(this._article.retrieveRange(this.list));
    }

    ngOnInit () {
        let page = this._params.get("page");
        if(page) {
            this.list.page = Number(page);
        }

        // check for size in cookie 'articles-per-page'

        let title = this._params.get("title");
        if (title) {
            this.list.title = title;
        }

        this.update();
    }

    size (size: number) {
        // set cookie 'articles-per-page'
    }

    page (page) {
        this.list.page = page;
        this._router.navigate([this.list.route, _.assign(this._params.params, { page: page })]);
        this.update();
    }

    search () {
        this.list.page = 1;
        let params = _.pick({
            title: this.list.title
        }, _.identity);
        this._router.navigate([this.list.route, params ]);
    }
}

PaginationComponent:

import { Component, Input, Output, EventEmitter, OnInit } from 'angular2/core';
import { RouteParams } from 'angular2/router';
import  _ from 'underscore';

import { List } from '../common/abstract';

@Component({
    selector: 'pagination',
    templateUrl: './pagination/index.html'
})
export class PaginationComponent implements OnInit {
    @Input() list: List;
    @Output() change  = new EventEmitter();

    pages: Array = [];

    constructor(
        private _params: RouteParams
    ) {}

    ngOnInit () {
        this.pages = _.range(1, this.list.pages + 1);
    }

    onClick (page: number) {
        if (page > 0 && page <= this.list.pages) {
            this.change.emit(page);
        }
        return false;
    }

    href (page: number) {
        return `${this.list.uri}?${_.map(_.assign(this._params.params, { page: page }), (value, param) => `${param}=${value}`).join('&')}`;
    }

    first (page) {
        return page == 1 ? 1 : null;
    }

    last(page) {
        return page == this.list.pages ? this.list.pages : null;
    }
}

Pagination Template (index.html) - I use bootstrap for styling

        

            
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Usage in article list template:

...

...

The article service in my little project requests a range of articles from the server using the Range header.

Hope you find this helpful!