How to detect drill mode

Hi alexpokerface ,
As dm-p said there is no simple straight forward method to check this. However, you can do try the following, all inside update():

1. dataView.metadata.dataRoles.drillableRoles — a map of role name → the DrillType[] currently available for it. When Drill Up is available for a role, the user has drilled down at least one level, which is the reliable "am I in a drilled-down state" signal:

import powerbi from "powerbi-visuals-api";
import DrillType = powerbi.DrillType;

public update(options: powerbi.extensibility.visual.VisualUpdateOptions😞 void {
    const dataRoles = options.dataViews?.[0]?.metadata?.dataRoles;
    const available = dataRoles?.drillableRoles?.["category"] ?? []; // role name from capabilities "drilldown".roles

    const isDrilledDown = available.indexOf(DrillType.Up) >= 0;   // Drill Up exists => below the top level
    const canDrillDown  = available.indexOf(DrillType.Down) >= 0; // more levels below
    const drillDisabled = dataRoles?.isDrillDisabled === true;    // drilling currently turned off
}

2. After any drill, Power BI just calls update() again with a new DataView. Read the level from the data — categorical: the number of categorical.categories and each categories[i].source.displayName (e.g., Year → Quarter → Month); matrix: the depth of matrix.rows.levels and each node's level. Note the category value type can change per level (Date at the top, string lower down), so guard with categories[i].source.type before parsing.

3. To drive drilling from your own UX (e.g., double-click to drill down), call host.drill(args) (API 4.7.0+), and optionally host.setCanDrill(true/false) (5.7.0+) to enable/disable it at runtime.

Good luck,
Asaf.

References

• The Drilldown API in Power BI visuals — documents the exact drillableRoles['...'].indexOf(powerbi.DrillType.Down) pattern and host.drill()
• Add drill-down support in Power BI visuals
• The dynamic drill-down API in Power BI visuals