1 files changed, 90 insertions, 0 deletions
diff --git a/gn2/wqflask/server_side.py b/gn2/wqflask/server_side.py
new file mode 100644
index 00000000..e661c407
--- /dev/null
+++ b/gn2/wqflask/server_side.py
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+# handles server side table processing
+
+
+class ServerSideTable:
+    """
+        This class is used to do server-side processing
+        on the DataTables table such as paginating, sorting,
+        filtering(not implemented) etc. This takes the load off
+        the client-side and reduces the size of data interchanged.
+
+        Usage:
+            ServerSideTable(rows_count, table_rows, header_data_names, request_values)
+        where,
+            `rows_count` as number of rows in the table,
+            `table_rows` as data rows of the table,
+            `header_data_names` as headers names of the table.
+            `request_values` must have request arguments values
+            including the DataTables server-side processing arguments.
+
+        Have a look at snp_browser_table() function in 
+        wqflask/wqflask/views.py for reference use.
+    """
+
+    def __init__(self, rows_count, table_rows, header_data_names, request_values):
+        self.request_values = request_values
+        self.sEcho = self.request_values['sEcho']
+
+        self.rows_count = rows_count
+        self.table_rows = table_rows
+        self.header_data_names = header_data_names
+
+        self.sort_rows()
+        self.paginate_rows()
+
+    def sort_rows(self):
+        """
+        Sorts the rows taking in to account the column (or columns) that the
+        user has selected.
+        """
+        def is_reverse(str_direction):
+            """ Maps the 'desc' and 'asc' words to True or False. """
+            return True if str_direction == 'desc' else False
+
+        if (self.request_values['iSortCol_0'] != "") and (int(self.request_values['iSortingCols']) > 0):
+            for i in range(0, int(self.request_values['iSortingCols'])):
+                column_number = int(self.request_values['iSortCol_' + str(i)])
+                column_name = self.header_data_names[column_number - 1]
+                sort_direction = self.request_values['sSortDir_' + str(i)]
+                self.table_rows = sorted(self.table_rows,
+                                         key=lambda x: x[column_name],
+                                         reverse=is_reverse(sort_direction))
+
+    def paginate_rows(self):
+        """
+        Selects a subset of the filtered and sorted data based on if the table
+        has pagination, the current page and the size of each page.
+        """
+        def requires_pagination():
+            """ Check if the table is going to be paginated """
+            if self.request_values['iDisplayStart'] != "":
+                if int(self.request_values['iDisplayLength']) != -1:
+                    return True
+            return False
+
+        if not requires_pagination():
+            return
+
+        start = int(self.request_values['iDisplayStart'])
+        length = int(self.request_values['iDisplayLength'])
+
+        # if search returns only one page
+        if len(self.table_rows) <= length:
+            # display only one page
+            self.table_rows = self.table_rows[start:]
+        else:
+            limit = -len(self.table_rows) + start + length
+            if limit < 0:
+                # display pagination
+                self.table_rows = self.table_rows[start:limit]
+            else:
+                # display last page of pagination
+                self.table_rows = self.table_rows[start:]
+
+    def get_page(self):
+        output = {}
+        output['sEcho'] = str(self.sEcho)
+        output['iTotalRecords'] = str(float('Nan'))
+        output['iTotalDisplayRecords'] = str(self.rows_count)
+        output['data'] = self.table_rows
+        return output