Update pagination (typicode#346)

Author: typicode

src/server/router/plural.js

@@ -32,6 +32,10 @@ module.exports = function (db, name) {
       })
   }
 
+  function getFullURL (req) {
+    return req.protocol + '://' + req.get('host') + req.originalUrl
+  }
+
   // GET /name
   // GET /name?q=
   // GET /name?attr=&attr=
@@ -156,8 +160,28 @@ module.exports = function (db, name) {
       _page = parseInt(_page, 10)
       _page = _page >= 1 ? _page : 1
       _limit = parseInt(_limit, 10) || 10
-      _start = (_page - 1) * _limit
-      chain = chain.slice(_start, _start + _limit)
+      var page = utils.getPage(chain.value(), _page, _limit)
+      var links = {}
+      var fullURL = getFullURL(req)
+
+      if (page.first) {
+        links.first = fullURL.replace('page=' + page.current, 'page=' + page.first)
+      }
+
+      if (page.prev) {
+        links.prev = fullURL.replace('page=' + page.current, 'page=' + page.prev)
+      }
+
+      if (page.next) {
+        links.next = fullURL.replace('page=' + page.current, 'page=' + page.next)
+      }
+
+      if (page.last) {
+        links.last = fullURL.replace('page=' + page.current, 'page=' + page.last)
+      }
+
+      res.links(links)
+      chain = _.chain(page.items)
     } else if (_end) {
       _start = parseInt(_start, 10) || 0
       _end = parseInt(_end, 10)

src/server/utils.js

@@ -1,5 +1,6 @@
 module.exports = {
-  toNative: toNative
+  toNative: toNative,
+  getPage: getPage
 }
 
 // Turns string to native.
@@ -22,3 +23,30 @@ function toNative (value) {
   }
   return value
 }
+
+function getPage (array, page, perPage) {
+  var obj = {}
+  var start = (page - 1) * perPage
+  var end = page * perPage
+
+  obj.items = array.slice(start, end)
+  if (obj.items.length === 0) {
+    return obj
+  }
+
+  if (page > 1) {
+    obj.prev = page - 1
+  }
+
+  if (end < array.length) {
+    obj.next = page + 1
+  }
+
+  if (obj.items.length !== array.length) {
+    obj.current = page
+    obj.first = 1
+    obj.last = Math.ceil(array.length / perPage)
+  }
+
+  return obj
+}

test/server/plural.js

@@ -270,8 +270,17 @@ describe('Server', function () {
     it('should paginate with a custom limit', function (done) {
       request(server)
         .get('/list?_page=2&_limit=1')
+        .set('host', 'localhost')
         .expect('Content-Type', /json/)
         .expect('x-total-count', db.list.length.toString())
+        .expect('link',
+          [
+            '<http://localhost/list?_page=1&_limit=1>; rel="first"',
+            '<http://localhost/list?_page=1&_limit=1>; rel="prev"',
+            '<http://localhost/list?_page=3&_limit=1>; rel="next"',
+            '<http://localhost/list?_page=15&_limit=1>; rel="last"'
+          ].join(', ')
+        )
         .expect('Access-Control-Expose-Headers', 'X-Total-Count')
         .expect(db.list.slice(1, 2))
         .expect(200, done)

test/server/utils.js

@@ -21,4 +21,76 @@ describe('utils', function () {
       assert.strictEqual(utils.toNative(true), true)
     })
   })
+
+  describe('getPage', function () {
+    var array = [1, 2, 3, 4, 5]
+    var perPage = 2
+
+    it('should return first page', function () {
+      assert.deepEqual(
+        utils.getPage(array, 1, perPage),
+        {
+          items: [1, 2],
+          current: 1,
+          first: 1,
+          next: 2,
+          last: 3
+        }
+      )
+    })
+
+    it('should return second page', function () {
+      assert.deepEqual(
+        utils.getPage(array, 2, perPage),
+        {
+          items: [3, 4],
+          current: 2,
+          first: 1,
+          prev: 1,
+          next: 3,
+          last: 3
+        }
+      )
+    })
+
+    it('should return third page (last)', function () {
+      assert.deepEqual(
+        utils.getPage(array, 3, perPage),
+        {
+          items: [5],
+          current: 3,
+          first: 1,
+          prev: 2,
+          last: 3
+        }
+      )
+    })
+
+    it('should return an empty array if page is greater than the last page', function () {
+      assert.deepEqual(
+        utils.getPage(array, 99, perPage),
+        {
+          items: []
+        }
+      )
+    })
+
+    it('should return the array if perPage is greater than the array size', function () {
+      assert.deepEqual(
+        utils.getPage(array, 1, 99),
+        {
+          items: array
+        }
+      )
+    })
+
+    it('should return an empty array if the array is empty', function () {
+      assert.deepEqual(
+        utils.getPage([], 1, 1),
+        {
+          items: []
+        }
+      )
+    })
+  })
 })