From 0a637ee67b68e1098cbecf6234f061c18c2a1c69 Mon Sep 17 00:00:00 2001
From: Patrizio Bekerle <patrizio.bekerle@tugraz.at>
Date: Tue, 16 Jul 2019 13:30:56 +0200
Subject: [PATCH] Initial commit with JSONLD class and basic utils.js
---
packages/common/jsonld.js | 221 +++++++++++++++++++++++++++++++++++
packages/common/package.json | 4 +
packages/common/utils.js | 44 +++++++
3 files changed, 269 insertions(+)
create mode 100644 packages/common/jsonld.js
create mode 100644 packages/common/package.json
create mode 100644 packages/common/utils.js
diff --git a/packages/common/jsonld.js b/packages/common/jsonld.js
new file mode 100644
index 00000000..ad80f9ff
--- /dev/null
+++ b/packages/common/jsonld.js
@@ -0,0 +1,221 @@
+"use strict";
+
+import utils from "./utils";
+
+let instances = {};
+let successFunctions = {};
+let failureFunctions = {};
+let initStarted = {};
+
+// "module.exports = class JSONLD" doesn't work with rollup because of above "import"
+export default class JSONLD {
+ constructor(baseApiUrl, entities) {
+ this.entities = entities;
+ this.baseApiUrl = baseApiUrl;
+
+ let idToEntityNameMatchList = {};
+ for (const entityName in entities) {
+ const id = entities[entityName]["@id"];
+ idToEntityNameMatchList[id] = entityName;
+ }
+
+ this.idToEntityNameMatchList = idToEntityNameMatchList;
+ }
+
+ static initialize(apiUrl, successFnc, failureFnc) {
+ // if init api call was already successfully finished execute the success function
+ if (instances[apiUrl] !== undefined) {
+ if (typeof successFnc == 'function') successFnc(instances[apiUrl]);
+
+ return;
+ }
+
+ // init the arrays
+ if (successFunctions[apiUrl] === undefined) successFunctions[apiUrl] = [];
+ if (failureFunctions[apiUrl] === undefined) failureFunctions[apiUrl] = [];
+
+ // add success and failure functions
+ if (typeof successFnc == 'function') successFunctions[apiUrl].push(successFnc);
+ if (typeof failureFnc == 'function') failureFunctions[apiUrl].push(failureFnc);
+
+ // check if api call was already started
+ if (initStarted[apiUrl] !== undefined) {
+ return;
+ }
+
+ initStarted[apiUrl] = true;
+
+ // window.VPUAuthToken will be set by on vpu-auth-init
+ document.addEventListener("vpu-auth-init", function(e)
+ {
+ const xhr = new XMLHttpRequest();
+ xhr.open("GET", apiUrl, true);
+ xhr.setRequestHeader('Authorization', 'Bearer ' + window.VPUAuthToken);
+
+ xhr.onreadystatechange = function () {
+ if (xhr.readyState === 4 && xhr.status === 200) {
+ const json = JSON.parse(xhr.responseText);
+
+ let entryPoints = {};
+ for (let property in json) {
+ // for some reason the properties start with a lower case character
+ if (!property.startsWith("@")) entryPoints[property.toLowerCase()] = json[property];
+ }
+
+ // read the link header of the api response
+// const utils = require("./utils");
+ const links = utils.parseLinkHeader(this.getResponseHeader("link"));
+
+ // get the hydra apiDocumentation url
+ const apiDocUrl = links["http://www.w3.org/ns/hydra/core#apiDocumentation"];
+
+ if (apiDocUrl !== undefined) {
+ // load the hydra apiDocumentation
+ const docXhr = new XMLHttpRequest();
+ docXhr.open("GET", apiDocUrl, true);
+ docXhr.setRequestHeader("Content-Type", "application/json");
+ docXhr.onreadystatechange = function () {
+ if (docXhr.readyState === 4 && docXhr.status === 200) {
+ const json = JSON.parse(docXhr.responseText);
+ const supportedClasses = json["hydra:supportedClass"];
+
+ let entities = {};
+ const baseUrl = utils.parseBaseUrl(apiUrl);
+
+ // gather the entities
+ supportedClasses.forEach(function (classData) {
+ // add entry point url
+ const entityName = classData["hydra:title"];
+ let entryPoint = entryPoints[entityName.toLowerCase()];
+ if (entryPoint !== undefined && !entryPoint.startsWith("http")) entryPoint = baseUrl + entryPoint;
+ classData["@entryPoint"] = entryPoint;
+
+ entities[entityName] = classData;
+ });
+
+ const instance = new JSONLD(baseUrl, entities);
+ instances[apiUrl] = instance;
+
+ // return the initialized JSONLD object
+ for (const fnc of successFunctions[apiUrl]) if (typeof fnc == 'function') fnc(instance);
+ successFunctions[apiUrl] = [];
+ } else {
+ for (const fnc of failureFunctions[apiUrl]) if (typeof fnc == 'function') fnc();
+ failureFunctions[apiUrl] = [];
+ }
+ };
+
+ docXhr.send();
+ } else {
+ for (const fnc of failureFunctions[apiUrl]) if (typeof fnc == 'function') fnc();
+ failureFunctions[apiUrl] = [];
+ }
+ } else {
+ for (const fnc of failureFunctions[apiUrl]) if (typeof fnc == 'function') fnc();
+ failureFunctions[apiUrl] = [];
+ }
+ };
+
+ xhr.send();
+ });
+ }
+
+ static getInstance(apiUrl) {
+ return instances[apiUrl];
+ }
+
+ getEntityForIdentifier(identifier) {
+ let entityName = this.getEntityNameForIdentifier(identifier);
+ return this.getEntityForEntityName(entityName);
+ }
+
+ getEntityForEntityName(entityName) {
+ return this.entities[entityName];
+ }
+
+ getApiUrlForIdentifier(identifier) {
+ return this.getEntityForIdentifier(identifier)["@entryPoint"];
+ }
+
+ getApiUrlForEntityName(entityName) {
+ return this.getEntityForEntityName(entityName)["@entryPoint"];
+ }
+
+ getEntityNameForIdentifier(identifier) {
+ return this.idToEntityNameMatchList[identifier];
+ }
+
+ getApiIdentifierList() {
+ let keys = [];
+ for (const property in this.idToEntityNameMatchList) {
+ keys.push(property);
+ }
+
+ return keys;
+ }
+
+ /**
+ * Expands a member of a list to a object with schema.org properties
+ *
+ * @param member
+ */
+ expandMember(member) {
+ const type = member["@type"];
+
+ const entity = this.getEntityForIdentifier(type);
+ let result = {"@id": member["@id"]};
+
+ entity["hydra:supportedProperty"].forEach(function (property) {
+ const id = property["hydra:property"]["@id"];
+ const title = property["hydra:title"];
+
+ result[id] = member[title];
+ });
+
+ return result;
+ }
+
+ /**
+ * Compacts an expanded member of a list to a object with local properties
+ *
+ * @param member
+ * @param localContext
+ */
+ static compactMember(member, localContext) {
+ let result = {};
+
+ for (const property in localContext) {
+ const value = member[localContext[property]];
+
+ if (value !== undefined) {
+ result[property] = value;
+ }
+ }
+
+ return result;
+ }
+
+ /**
+ * Transforms hydra members to a local context
+ *
+ * @param data
+ * @param localContext
+ * @returns {Array}
+ */
+ transformMembers(data, localContext) {
+ const members = data['hydra:member'];
+
+ if (members === undefined || members.length === 0) {
+ return [];
+ }
+
+ let results = [];
+ let that = this;
+
+ members.forEach(function (member) {
+ results.push(JSONLD.compactMember(that.expandMember(member), localContext));
+ });
+
+ return results;
+ }
+};
diff --git a/packages/common/package.json b/packages/common/package.json
new file mode 100644
index 00000000..845728d5
--- /dev/null
+++ b/packages/common/package.json
@@ -0,0 +1,4 @@
+{
+ "name": "vpu-common",
+ "version": "1.0.1"
+}
diff --git a/packages/common/utils.js b/packages/common/utils.js
new file mode 100644
index 00000000..4773eded
--- /dev/null
+++ b/packages/common/utils.js
@@ -0,0 +1,44 @@
+module.exports = {
+ /**
+ * Parses a link header
+ *
+ * The node module parse-link-header didn't work, so https://gist.github.com/niallo/3109252 became handy
+ *
+ * @param header
+ */
+ parseLinkHeader: (header) => {
+ if (header.length === 0) {
+ throw new Error("input must not be of zero length");
+ }
+
+ // Split parts by comma
+ const parts = header.split(',');
+ const links = {};
+
+ // Parse each part into a named link
+ for(let i=0; i<parts.length; i++) {
+ const section = parts[i].split(';');
+ if (section.length !== 2) {
+ throw new Error("section could not be split on ';'");
+ }
+ const url = section[0].replace(/<(.*)>/, '$1').trim();
+ const name = section[1].replace(/rel="(.*)"/, '$1').trim();
+ links[name] = url;
+ }
+
+ return links;
+ },
+
+ /**
+ * Parses the base url from an url
+ *
+ * @param url
+ * @returns {string}
+ */
+ parseBaseUrl: (url) => {
+ const pathArray = url.split('/');
+ const protocol = pathArray[0];
+ const host = pathArray[2];
+ return protocol + '//' + host;
+ },
+};
--
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