Cascade or drill-down forms are the types of forms that the values listed in one field depend on the value selected in another field.

In this example, we have multiple databases:

  • car-model
  • car-manufacturer
  • car-types
  • wheel-check
  • color

In the steps below, we will capture points representing car layer: the choices from the value relation will be filtered based on the previous field user picks. For example, if user selects Trucks as Car type (truck/car), the Car-Manufacturer field will present user with DAF Trucks, Scania or MAN. Likewise, the next drop-down menu for Car-Model will change accordingly based on the Car-Manufacturer selection.

QGIS

To set up a the cascade form:

  • Download and open this example project in QGIS
  • From the layer panel, right-click on car layer and select Properties
  • In the new window, select Attributes form

Notes:

  • See Value Relations configuration for the following fields:
    • Car-Type
    • Car-Manufacturer
    • Car-Model
    • Colorized
    • Wheel-Check
  • See also Filter expressions applied to the following fields:
    • Car-Manufacturer
    • Car-Model
    • Wheel-Check

In addition to the value relations in the survey layer, we need to set up value relation for the following non-spatial tables and the associated fields: - manufacturer field from car-model table - type field from car-manufacturer table - car-type field from wheel-check table

Input

To use the cascade form in Input:

  • Open Input on your device and from Projects > Explore download documentation\form_cascade
  • Open the project
  • Select Record and add a point
  • The form will appear
  • Under Survey tab, for Car-type select Car.
  • Manufacturer field should short list Mercedes-Benz, Skoda and Audi. Select Audi
  • For Car-Model select A8

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