added paging functionality

src/main/resources/static/contentUtility.js

@@ -1,22 +1,28 @@
-import {searchBarTimeout, searchSection} from "./main.js"
+import {searchBarTimeout, searchSection, lastQuery} from "./main.js"
 import Dataset from "./dataset.js"
 
-export function fetchQuery(fetchString) {
+export function fetchQuery(fetchString, clearResults) {
     clearTimeout(searchBarTimeout);
     fetch(fetchString)
         .then(resp => resp.json())
         .then((data) => {
-            parseContent(data.content);
+            parseContent(data.content, clearResults);
+            lastQuery.totalPages = data.totalPages;
+            if (clearResults) {
+                lastQuery.currentPage = 0;
+            }
         });
 }
 
-function parseContent(content) {
+function parseContent(content, clearResults) {
     if (content.length === 0) {
         searchSection.querySelector("#nothing-found ").classList.remove("hidden");
     } else {
         searchSection.querySelector("#nothing-found").classList.add("hidden");
         const datasets = content.map(dataset => new Dataset(dataset));
-        Array.from(searchSection.querySelectorAll(".datasets .dataset")).forEach(e => e.remove());
+        if (clearResults) {
+            Array.from(searchSection.querySelectorAll(".datasets .dataset")).forEach(e => e.remove());
+        }
         for (const dataset of datasets) {
             searchSection.querySelector(".datasets").appendChild(dataset.createDatasetHTMLElement());
         }

src/main/resources/static/main.js

@@ -4,7 +4,7 @@ import Dataset from "./dataset.js";
 const apiEndpoint = "/api/v1/datasets";
 const baseURL = location.origin;
 const defaultPagingValue = 20;
-const lastQuery = {
+export const lastQuery = {
     url: "",
     totalPages: 0,
     currentPage: 0
@@ -35,12 +35,12 @@ addButton.addEventListener("click", () => {
 filterButton.addEventListener("change", () => {
     const filterString = filterButton.value;
     if (filterString !== filterButton.querySelector("#default-filter").value) {
-        fetchQuery(createQuery());
+        fetchQuery(createQuery(), true);
     }
 });
 
 searchButton.addEventListener("click", () => {
-    fetchQuery(createQuery());
+    fetchQuery(createQuery(), true);
 
 });
 
@@ -48,18 +48,18 @@ searchBar.addEventListener("input", () => {
     updateSections();
     clearTimeout(searchBarTimeout);
     searchBarTimeout = setTimeout(() => {
-        fetchQuery(createQuery());
+        fetchQuery(createQuery(), true);
     }, searchDelay);
 });
 
 searchBar.addEventListener('keypress', function (e) {
     if (e.key === 'Enter') {
-        fetchQuery(createQuery());
+        fetchQuery(createQuery(), true);
     }
 });
 
 sortButton.addEventListener("change", () => {
-    fetchQuery(createQuery());
+    fetchQuery(createQuery(), true);
 });
 
 resetButton.addEventListener("click", () => {
@@ -79,7 +79,7 @@ for (const upvoteButton of upvoteButtons) {
 }
 
 // Consider moving this to datasets.js completely
-const downvoteButtonClickListener = e  => {
+const downvoteButtonClickListener = e => {
     const entryID = e.target.parentElement.parentElement.dataset.id;
     vote(entryID, false);
 };
@@ -93,7 +93,7 @@ function navigateToAdd() {
 }
 
 function getFilterQuery() {
-    let filterString= filterButton.value.toUpperCase();
+    let filterString = filterButton.value.toUpperCase();
     if (filterString === "NONE") {
         return ["type", "%"]
     } else if (document.querySelector('#filter-btn option:checked').parentElement.label === "Standard categories") {
@@ -141,13 +141,14 @@ export function vote(entryID, up) {
         method: "PUT",
         headers: {
             'Content-Type': 'application/json',
-        }})
-    .then(resp => resp.json())
-    .then((data) => {
-        console.log(data.upvotes); // TODO: remove, check einbauen: data.id === entryID?
-    let dataset = document.querySelector('[data-id= ' + CSS.escape(entryID) + ']')
-    dataset.querySelector("span").innerText = data.upvotes;
-    });
+        }
+    })
+        .then(resp => resp.json())
+        .then((data) => {
+            console.log(data.upvotes); // TODO: remove, check einbauen: data.id === entryID?
+            let dataset = document.querySelector('[data-id= ' + CSS.escape(entryID) + ']')
+            dataset.querySelector("span").innerText = data.upvotes;
+        });
 }
 
 function incrementPageCount() {
@@ -173,7 +174,7 @@ function updateSections() {
 // fetches the further categories used in the filter function
 function fetchCategories() {
     const fetchURL = new URL(
-        "api/v1/categories" , baseURL);
+        "api/v1/categories", baseURL);
     fetch(fetchURL)
         .then(resp => resp.json())
         .then((data) => {
@@ -217,6 +218,21 @@ window.onload = function () {
     fetchInitialEntries();
     updateSections();
     if (searchBar.value !== "") {
-        fetchQuery(createQuery());
+        fetchQuery(createQuery(), true);
+    }
+    let observer = new IntersectionObserver(() => {
+        if (!searchSection.classList.contains("hidden")) {
+            fetchPagingResults();
+        }
+    }, {root: null, rootMargin: "0px", threshold: .9});
+    observer.observe(document.getElementById("observable"));
+}
+
+function fetchPagingResults() {
+    lastQuery.currentPage++
+    if (lastQuery.currentPage < lastQuery.totalPages) {
+        let pagingQuery = new URL(createQuery());
+        pagingQuery.searchParams.append("page", lastQuery.currentPage.toString(10));
+        fetchQuery(pagingQuery, false);
     }
 }

src/main/resources/templates/index.html

@@ -78,6 +78,7 @@
             </div>
             <ul class="datasets">
             </ul>
+            <div id="observable" style="height: 2rem"></div>
         </section>
     </main>
 </body>