Unable to select a layer in the Search Settings section of the District Lookup widget

Description

When configuring the District Lookup widget in Web AppBuilder for ArcGIS, selecting a layer in the Search Settings section returns the following warning message:

Please select a polygon layer which has a related point layer.

Cause

The following are three possible reasons for this issue:

• The data have a one-to-many (1:M) relationship. However, the layer in the District Lookup widget only requires a one-to-one (1:1) cardinality in the relationship class. For more information, refer to the following link: District Lookup widget
• There is no relationship class associated with the data layer.
• The data consist of on-the-fly relates, which are not maintained once the layer is published as a feature service.

Solution or Workaround

1. In ArcMap, create a new 1:1 relationship class. For more information, refer to the following link: Creating a simple relationship class
2. Publish the layer as a feature service before using the District Lookup widget in Web AppBuilder for ArcGIS. For more information, refer to the following link: Publishing a map service