onion/js/utils/fetch_api_utils.js

'use strict';

import Q from 'q';

import { sanitize } from './general_utils';
import AppConstants from '../constants/application_constants';

// TODO: Create Unittests that test all functions

    /**
     * Takes a key-value object of this form:
     *
     *  {
     *     'page': 1,
     *     'pageSize': 10
     *  }
     *
     * and converts it to a query-parameter, which you can append to your URL.
     * The return looks like this:
     *
     * ?page=1&page_size=10
     *
     * CamelCase gets converted to snake_case!
     *
     */
export function argsToQueryParams(obj) {

    obj = sanitize(obj);

    return Object
            .keys(obj)
            .map((key, i) => {
                let s = '';

                if(i === 0) {
                    s += '?';
                } else {
                    s += '&';
                }

                let snakeCaseKey = key.replace(/[A-Z]/, (match) => '_' + match.toLowerCase());

                return s + snakeCaseKey + '=' + encodeURIComponent(obj[key]);
            })
            .join('');
}

/**
 * Takes a string and a boolean and generates a string query parameter for
 * an API call.
 */
export function generateOrderingQueryParams(orderBy, orderAsc) {
    let interpolation = '';

    if(!orderAsc) {
        interpolation += '-';
    }

    return interpolation + orderBy;
}

export function status(response) {
    if (response.status >= 200 && response.status < 300) {
        return response;
    }
    throw new Error(response.json());
}

export function getCookie(name) {
    let parts = document.cookie.split(';');
    
    for(let i = 0; i < parts.length; i++) {
        if(parts[i].indexOf(AppConstants.csrftoken + '=') > -1) {
            return parts[i].split('=').pop();
        }
    }
}

/*

    Given a url for an image, this method fetches it and returns a promise that resolves to
    a blob object.
    It can be used to create a 64base encoded data url.

    Taken from: http://jsfiddle.net/jan_miksovsky/yy7zs/

    CURRENTLY NOT USED...

 */
export function fetchImageAsBlob(url) {
    return Q.Promise((resolve, reject) => {
        let xhr = new XMLHttpRequest();

        xhr.open('GET', url, true);

        // Ask for the result as an ArrayBuffer.
        xhr.responseType = 'arraybuffer';

        xhr.onreadystatechange = function() {
            if(xhr.readyState === 4 && xhr.status >= 400) {
                reject(xhr.statusText);
            }
        };

        xhr.onload = function() {
            // Obtain a blob: URL for the image data.
            let arrayBufferView = new Uint8Array(this.response);
            let blob = new Blob([arrayBufferView], {type: 'image/jpeg'});
            resolve(blob);
        };

        xhr.send();
    });
}