feat: Added pagination support to environments endpoint (#1665)

Co-authored-by: Nilver Viera <nviera@itosupport.com>
Co-authored-by: Nick Satterly <nfsatterly@gmail.com>

alerta/database/backends/postgres/base.py

@@ -632,14 +632,14 @@ def get_topn_standing(self, query=None, topn=100):
 
     # ENVIRONMENTS
 
-    def get_environments(self, query=None, topn=1000):
+    def get_environments(self, query=None, page=None, page_size=None):
         query = query or Query()
         select = f"""
             SELECT environment, severity, status, count(1) FROM alerts
             WHERE {query.where}
             GROUP BY environment, CUBE(severity, status)
         """
-        result = self._fetchall(select, query.vars, limit=topn)
+        result = self._fetchall(select, query.vars, limit=page_size)
 
         severity_count = defaultdict(list)
         status_count = defaultdict(list)
@@ -654,7 +654,7 @@ def get_environments(self, query=None, topn=1000):
                 total_count[row.environment] = row.count
 
         select = """SELECT DISTINCT environment FROM alerts"""
-        environments = self._fetchall(select, {})
+        environments = self._fetchall(select, {}, limit=page_size, offset=(page - 1) * page_size)
         return [
             {
                 'environment': e.environment,
@@ -663,6 +663,14 @@ def get_environments(self, query=None, topn=1000):
                 'count': total_count[e.environment]
             } for e in environments]
 
+    def get_environments_count(self, query=None):
+        query = query or Query()
+        select = """
+            SELECT COUNT(DISTINCT environment) FROM alerts
+             WHERE {where}
+        """.format(where=query.where)
+        return self._fetchone(select, query.vars).count
+
     # SERVICES
 
     def get_services(self, query=None, topn=1000):

alerta/database/base.py

@@ -204,7 +204,10 @@ def get_topn_standing(self, query, group='event', topn=100):
 
     # ENVIRONMENTS
 
-    def get_environments(self, query=None, topn=1000):
+    def get_environments(self, query=None, page=1, page_size=100):
+        raise NotImplementedError
+
+    def get_environments_count(query: Query = None) -> int:
         raise NotImplementedError
 
     # SERVICES

alerta/models/alert.py

@@ -542,8 +542,12 @@ def get_topn_standing(query: Query = None, topn: int = 10) -> List[Dict[str, Any
 
     # get environments
     @staticmethod
-    def get_environments(query: Query = None) -> List[str]:
-        return db.get_environments(query)
+    def get_environments(query: Query = None, page: int = 1, page_size: int = 100) -> List[str]:
+        return db.get_environments(query, page, page_size)
+
+    @staticmethod
+    def get_environments_count(query: Query = None) -> int:
+        return db.get_environments_count(query)
 
     # get services
     @staticmethod

alerta/views/alerts.py

@@ -480,19 +480,30 @@ def get_topn_standing():
 @jsonp
 def get_environments():
     query = qb.alerts.from_params(request.args, customers=g.customers)
-    environments = Alert.get_environments(query)
+    total = Alert.get_environments_count(query)
+    paging = Page.from_params(request.args, total)
+    environments = Alert.get_environments(query, page=paging.page, page_size=paging.page_size)
 
     if environments:
         return jsonify(
             status='ok',
             environments=environments,
-            total=len(environments)
+            page=paging.page,
+            pageSize=paging.page_size,
+            pages=paging.pages,
+            more=paging.has_more,
+            total=total
+
         )
     else:
         return jsonify(
             status='ok',
             message='not found',
             environments=[],
+            page=paging.page,
+            pageSize=paging.page_size,
+            pages=paging.pages,
+            more=paging.has_more,
             total=0
         )