Use POST instead of GET for Query Tool downloads to avoid errors with long queries. Fixes #4013

web/pgadmin/tools/sqleditor/__init__.py

@@ -1389,7 +1389,7 @@ def save_file():
 
 @blueprint.route(
     '/query_tool/download/<int:trans_id>',
-    methods=["GET"],
+    methods=["POST"],
     endpoint='query_tool_download'
 )
 @login_required
@@ -1401,7 +1401,7 @@ def start_query_download_tool(trans_id):
     if status and sync_conn is not None and \
        trans_obj is not None and session_obj is not None:
 
-        data = request.args if request.args else None
+        data = request.values if request.values else None
         try:
             if data and 'query' in data:
                 sql = data['query']

web/pgadmin/tools/sqleditor/static/js/sqleditor.js

@@ -3564,17 +3564,14 @@ define('tools.querytool', [
         var self = this,
           url = url_for('sqleditor.query_tool_download', {
             'trans_id': self.transId,
-          });
-
-        url += '?' + $.param({
-          query: query,
-          filename: filename,
-        });
+          }),
+          data = { query: query, filename: filename };
 
         // Get the CSV file
         self.download_csv_obj = $.ajax({
-          type: 'GET',
+          type: 'POST',
           url: url,
+          data: data,
           cache: false,
           async: true,
           xhrFields: {