Calculated values not displayed in ArcGIS Field Maps

Description

When configuring a calculated expression for a field in an ArcGIS Field Maps form, the field displays double dashes (--) instead of returning the expected calculated values during form entry. This indicates the expression failed to return a valid result.

Cause

The calculated expression is applied to a read-only field in feature layers published from ArcGIS Pro or created in ArcGIS Online. As a result, ArcGIS Field Maps cannot write the output of the expression to the field.

To support calculated expressions, the form element is non-editable by default to prevent manual input while the field must remain editable to allow Field Maps to save the calculated value.

Solution or Workaround

Disable the Read Only option for the field in ArcGIS Pro

1. Open the ArcGIS Pro project containing the feature layer.
2. Open the Fields view of the feature layer.
3. In the Fields view, uncheck the Read Only check box for the field.

4. On the ribbon, click Save in the Manage Edits group to save the edits.
5. Overwrite the web feature layer. Refer to ArcGIS Pro: Overwrite a web feature layer for instructions.

Enable attribute editing for the field in ArcGIS Online

1. In ArcGIS Online, on the feature layer’s item page, click the Data tab.
2. Click the Fields tab.
3. On the field row, click the ellipsis and select View details.
4. Toggle Allow attribute editing on and click Save.