Renders an Apache ECharts gauge chart displaying a single numeric value.
ECHARTSGAUGE — 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 should return a single row; if two columns are present, column 1 is used as the value, otherwise column 0. Option building is handled by ObjReportEchartsbase._build_gauge_option. The tooltip formatter is "{a} <br/>{b} : {c}%".