GDB Step-by-Step Step 4: Create GDB Domains
| Step 4: Create GDB Domains |
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Domains are the ranges or sets of valid attribute values that can be recorded for a feature class. They are critical in enforcing data integrity in the GDB.A single domain can be used for a number of feature classes in the geodatabase. In our exercise, we will reuse the domains shaded in the below chart for multiple feature classes.
1. To create domains for the Training_Day1 geodatabase Since domains are a property of the geodatabase, right-click on the geodatabase and choose Properties Click on the Domains tab
2. To create a range domain for the height of the light pole Click on the first blank line in the Domain Name column Enter Height_Feet
Tip The following characters are invalid and not allowed within the domain name. `~@#$%^&*()+=|,<>?{}.!'{}:;
Design Note This domain could have been Pole_Height_Feet. The more generic name of Height_Feet will allow users to record the heights of other features that are 1-100 feet tall. There is no ‘correct’ choice as it depends on the nature of the other feature classes in your geodatabase.
3. To enter a description for this domain Descriptions, like aliases, do not have to adhere to the limitations of the database, so they can contain special characters such as spaces. By specifying a description, you can give use more "user friendly" description of the content of the field than their actual domain name. Press the tab key to advance to the Description column
4. To specify a Field Type of Short Integer In the Domain Properties window, from the Field Type drop-down menu change the default entry from Long Integer to Short Integer
5. To specify the Domain Type of Range In the Domain Type drop down list, notice the Range is automatically chosen. To review the various domain and field types, refer to the section describing the components of a GDB on this site.
6. To specify the range of valid values Since valid values for height can be 1-100, enter these Minimum and Maximum Values in the next two windows.
The Split and Merge policies refer to behaviors during the editing process. These policies are outside the scope of this course and will not be covered here.
The completed window should look like this – Upon recording this location by GPS, ArcPad will prompt you to enter a numeric value for the field Height_Feet. After you do so, ArcPad will check to that you entered an integer that falls between the minimum and maximum values specified. If your entry does not meet these criteria, ArcPad will prompt you to re-enter a new value. This is enforced data integrity.
7. ON YOUR OWN As you did for Height_Feet, create the Short Integer, Range domains for Width_Feet and Wattage as shown.
The completed window should look like this -
8. To create the coded value domain named Pole_Material Coded domains allow you to choose attribute values from a drop-down menu rather than entering character-by-character text. Since tapping the mobile device virtual keyboard with complete accuracy is somewhat challenging, use coded values to ensure accurate data entry whenever possible.
Click on the first blank line in the Domain Name column Enter Pole_Material and provide a Description A description is required for each domain name.
In the Domain Properties window, specify the Field Type of Text Text fields can only be of the coded value domain type, so the Coded Values is already chosen as the domain type from the drop down list Leave the Split and Merge Policy choices as Default Values
9. To populate the attribute values choices These choices will appear in the drop-down list as you record feature attributes on the mobile device In the Coded Values portion of the dialog box, click on the first blank Code column, and enter Metal In the Description column, enter a corresponding description While collecting GPS data, ArcPad will prompt you to choose from a list of possible attribute values; the choices in the drop-down menu are those listed in the Description column. Continue to enter the remaining codes and descriptions for Wood, Concrete and Other.
Tip If all appears ok but the window will not close, delete domains that appear empty as most likely, the Enter key has introduced a blank space in the domain name and the window is awaiting the required description for the ‘blank’ domain. In the future, to prevent this from happening, use the tab key or click the mouse button move around in this window.
The completed window should look like this -
To review the need for backdoors, refer the GDB Basics material on this site.
Tip Should you wish to enter a value that is not in the drop-down list, the ‘Other’ attribute value allows you a way to convey this. Although you will not be able to enter the actual answer (i.e. Mix of Metal and Wood), we have designed a ‘backdoor’ for doing capturing this information. This backdoor is the Comment attribute, which does allow for the entry of free-form text.
10. ON YOUR OWN i. As you did for Pole_Material, create the Coded Value, Text domains for the Surface and Condition
The completed windows should look like this -
ii. Create domains as needed for the feature classes you designed on your own. You have now created all the domains needed for the geodatabase.
In the next and almost final step, you will pair these geodatabase domains with the appropriate feature classes fields.
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