From f0006c92f0e741bc7743b2ca8d86851a63f8b3d6 Mon Sep 17 00:00:00 2001
From: Tim-Hinnerk Heuer <th.heuer@gmail.com>
Date: Fri, 3 Jan 2020 02:50:19 +1300
Subject: [PATCH] Issue 310 (#311)

* fix item previous and next links #310

* fix get_next comment #310

* ensure correct formatting for flake8 #310

* change id to id_

* change previous to prev

* fix ref

* Update item.html

Co-authored-by: Tom Kralidis <tomkralidis@gmail.com>
---
 pygeoapi/provider/postgresql.py | 40 +++++++++++++++++++++++++++++++++
 pygeoapi/templates/item.html    | 34 ++++++++++++++++++----------
 2 files changed, 62 insertions(+), 12 deletions(-)

diff --git a/pygeoapi/provider/postgresql.py b/pygeoapi/provider/postgresql.py
index 08eafd1..d0c0b79 100644
--- a/pygeoapi/provider/postgresql.py
+++ b/pygeoapi/provider/postgresql.py
@@ -265,6 +265,44 @@ class PostgreSQLProvider(BaseProvider):
 
             return feature_collection
 
+    def get_previous(self, cursor, identifier):
+        """
+        Query previous ID given current ID
+
+        :param identifier: feature id
+
+        :returns: feature id
+        """
+        sql = 'SELECT {} AS id FROM {} WHERE {}<%s ORDER BY {} DESC LIMIT 1'
+        cursor.execute(SQL(sql).format(
+            Identifier(self.id_field),
+            Identifier(self.table),
+            Identifier(self.id_field),
+            Identifier(self.id_field),
+        ), (identifier,))
+        item = cursor.fetchall()
+        id_ = item[0]['id']
+        return id_
+
+    def get_next(self, cursor, identifier):
+        """
+        Query next ID given current ID
+
+        :param identifier: feature id
+
+        :returns: feature id
+        """
+        sql = 'SELECT {} AS id FROM {} WHERE {}>%s ORDER BY {} LIMIT 1'
+        cursor.execute(SQL(sql).format(
+            Identifier(self.id_field),
+            Identifier(self.table),
+            Identifier(self.id_field),
+            Identifier(self.id_field),
+        ), (identifier,))
+        item = cursor.fetchall()
+        id_ = item[0]['id']
+        return id_
+
     def get(self, identifier):
         """
         Query the provider for a specific
@@ -298,6 +336,8 @@ class PostgreSQLProvider(BaseProvider):
             row_data = cursor.fetchall()[0]
             feature = self.__response_feature(row_data)
 
+            feature['prev'] = self.get_previous(cursor, identifier)
+            feature['next'] = self.get_next(cursor, identifier)
             return feature
 
     def __response_feature(self, row_data):
diff --git a/pygeoapi/templates/item.html b/pygeoapi/templates/item.html
index 5b5b171..037a4ec 100644
--- a/pygeoapi/templates/item.html
+++ b/pygeoapi/templates/item.html
@@ -37,7 +37,28 @@
       </div>
       <div class="row">
         <div class="col-md-6 col-sm-12">
-          <div id="items-map"></div>
+          <div class="row">
+            <div class="col-sm-12">
+              <div id="items-map"></div>
+            </div>
+          </div>
+          <div class="row">
+            <div class="col-sm-12">
+              {% if data['prev'] or data['next'] %}
+              <div class="row">
+                <div class="col-sm-12">
+                  {% for link in data['links'] %}
+                  {% if link['rel'] == 'prev' %}
+                  <a role="button" href="./{{ data['prev'] }}">Previous</a>
+                  {% elif link['rel'] == 'next' %}
+                  <a role="button" href="./{{ data['next'] }}">Next</a>
+                  {% endif %}
+                  {% endfor %}
+                </div>
+              </div>
+              {% endif %}
+            </div>
+          </div>
         </div>
         <div class="col-md-6 col-sm-12">
             <table class="striped">
@@ -72,17 +93,6 @@
             </table>
         </div>
       </div>
-      <div class="row">
-          <div class="col-sm-12">
-          {% for link in data['links'] %}
-            {% if link['rel'] == 'prev' %}
-            <a role="button" href="{{ link['href'] }}?f=html">Prev</a>
-            {% elif link['rel'] == 'next' %}
-            <a role="button" href="{{ link['href'] }}?f=html">Next</a>
-            {% endif %}
-          {% endfor %}
-          </div>
-        </div>
     </section>
 {% endblock %}