Renders an Apache ECharts funnel chart for visualising sequential stage volumes.
ECHARTSFUNNEL — set as ReportType in def_report.
def Render(self, Param1="", Param2="", Param3="") -> str:
Inherited from ObjReportEchartsbase. Param1, Param2, and Param3 are forwarded in the RPC payload for SQL token substitution. Returns an HTML string containing a styled panel and an ECharts initialisation script.
Uses the Apache ECharts JS library. The SQL query must return rows with two columns: stage name and numeric value. Option building is handled by ObjReportEchartsbase._build_funnel_option.