87 lines
3.1 KiB
JavaScript
87 lines
3.1 KiB
JavaScript
// Copyright IBM Corp. 2016. All Rights Reserved.
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// Node module: strong-error-handler
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// This file is licensed under the MIT License.
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// License text available at https://opensource.org/licenses/MIT
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'use strict';
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var accepts = require('accepts');
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var debug = require('debug')('strong-error-handler:http-response');
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var sendJson = require('./send-json');
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var sendHtml = require('./send-html');
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var util = require('util');
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module.exports = negotiateContentProducer;
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/**
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* Handles req.accepts and req.query._format and options.defaultType
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* to resolve the correct operation
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*
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* @param req request object
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* @param {Object} options options of strong-error-handler
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* @returns {Function} Opeartion function with signature `fn(res, data)`
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*/
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function negotiateContentProducer(req, options) {
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var SUPPORTED_TYPES = [
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'application/json', 'json',
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'text/html', 'html',
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];
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options = options || {};
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var defaultType = 'json';
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// checking if user provided defaultType is supported
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if (options.defaultType) {
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if (SUPPORTED_TYPES.indexOf(options.defaultType) > -1) {
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debug('Accepting options.defaultType `%s`', options.defaultType);
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defaultType = options.defaultType;
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} else {
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debug('defaultType: `%s` is not supported, ' +
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'falling back to defaultType: `%s`', options.defaultType, defaultType);
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}
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}
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// decide to use resolvedType or defaultType
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// Please note that accepts assumes the order of content-type is provided
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// in the priority returned
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// example
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// Accepts: text/html, */*, application/json ---> will resolve as text/html
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// Accepts: application/json, */*, text/html ---> will resolve as application/json
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// Accepts: */*, application/json, text/html ---> will resolve as application/json
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// eg. Chrome accepts defaults to `text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*`
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// In this case `resolvedContentType` will result as: `text/html` due to the order given
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var resolvedContentType = accepts(req).types(SUPPORTED_TYPES);
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debug('Resolved content-type', resolvedContentType);
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var contentType = resolvedContentType || defaultType;
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// to receive _format from user's url param to overide the content type
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// req.query (eg /api/Users/1?_format=json will overide content negotiation
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// https://github.com/strongloop/strong-remoting/blob/ac3093dcfbb787977ca0229b0f672703859e52e1/lib/http-context.js#L643-L645
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var query = req.query || {};
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if (query._format) {
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if (SUPPORTED_TYPES.indexOf(query._format) > -1) {
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contentType = query._format;
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} else {
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// format passed through query but not supported
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var msg = util.format('Response _format "%s" is not supported' +
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'used "%s" instead"', query._format, defaultType);
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res.header('X-Warning', msg);
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debug(msg);
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}
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}
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debug('Content-negotiation: req.headers.accept: `%s` Resolved as: `%s`',
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req.headers.accept, contentType);
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return resolveOperation(contentType);
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}
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function resolveOperation(contentType) {
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switch (contentType) {
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case 'application/json':
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case 'json':
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return sendJson;
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case 'text/html':
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case 'html':
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return sendHtml;
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}
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}
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