The currently selected data source does not contain a valid geospatial attribute

When configuring a map, you may get this error:

The currently selected data source does not contain a valid geospatial attribute, 
which is required in order to configure the component properly. Please select a different data source.

To resolve this error:

• just create a field which is a concatenation of the longitude and latitude data.
• and add the “mdexType” geospatial type “mdex:geocode” to the field in the metadata