Though Google App Engine does not yet support modifiable unique fields, we believe that this is an important requirement for many business apps. So, we have added this feature in our framework layer over Google App Engine to enable unique fields in our Free CRM for Google Apps Engine and in our online database app-builder for Google App Engine.
This feature has been turned on for the email-id fields in iFreeTools CRM - for Lead, Vendor, Contact and User records. The value entered for these fields will be trimmed to remove spaces and converted to lower case, before a unique constraint check is performed, when adding or modifying records.
We will see how this feature can be used in a custom application over iFreeTools Creator. Vehicle registration details in one case where unique values are to be stored for each of the vehicle records. You do not want a duplicate entry to be entered inadvertently into your database. So for the this field, we will enable the Unique constraint and also use the transformation functions trim and upper.
Now, we will proceed to add a record with a duplicate value for this unique field. Notice how the value is given in a lower case and with additional spaces prefixed and suffixed..
When trying to save this record, we will be shown the error message as given in the image below. You will also find that the value has been trimmed and turned to upper-case..
The unique constraints are also enforced during bulk import of data from CSV.
Hope you find the feature useful. Feel free to send in your feedback.