Renders a doughnut chart using Chart.js v2 with a fixed colour palette and no legend.
Doughnut — set as ReportType in def_report.
def Render(self, Param1="", Param2="", Param3="") -> str:
Returns an HTML <canvas> element and an inline <script> that initialise a Chart.js v2 doughnut chart. The query must return two columns: label (column 1) and numeric value (column 2). An optional third column adds a second dataset. Segment colours are hardcoded from a predefined palette; the legend is hidden.
Requires chart.min.js. Uses Chart.js v2 API (new Chart(ctx, {type: 'doughnut', ...})). The canvas is fixed at width="100" height="80".