Introduction
Aliases are alternative names for fields in a dataset that are often more descriptive than the field names themselves. Most FME users who work with a geodatabase will want to create or maintain field aliases in their datasets. When adding a file geodatabase to a workspace, alias control is available under Schema Attributes > Alias Mode.
Alias Mode controls how geodatabase aliases are used.
- None: Aliases are ignored.
- Replace Attribute Names with Aliases: Attributes on feature types will be named based on their aliases rather than their official names. A geodb_feature_class_alias attribute will be included on each feature. Use this mode when the target format should create feature types using aliases as attribute names.
- Expose Aliases as Metadata Attributes: For each attribute read, a second <name>_alias attribute will be added that stores the alias for the attribute in question. A geodb_feature_class_alias attribute will also be included on each feature. Use this mode when the target format is a geodatabase, and the aliases should be preserved during feature class and table creation.
Requirements
The Esri Geodatabase (File Geodb) reader/writer used in the following example requires that a licensed version of ArcGIS be available to the user. For more information on required ArcGIS license levels, please see Required ArcGIS License Types for FME Geodatabase Formats.
Source Data
Community Centres (Esri File Geodatabase Feature Class)
In the above image, we see a visualization of the Community Centres feature class and its accompanying attributes, which contain Name, Address, and Website URL values for the various community centres located in the city of Vancouver. By examining the properties of this feature class, one can see that field aliases are present in the data.
Step-by-step Instructions
To follow along with the tutorial, download the data from the article's Files section.
1. Read Source Data
Open a blank workspace in FME Workbench. Add a reader to the canvas and set the following:
- Format: Esri Geodatabase (File Geodb)
-
Dataset: CommunityMap.gdb
- Click on the ellipses to navigate to the location of the file on your computer
Click Parameters.
In the Parameters, click the ellipsis next to Table, then select Community Centres.
Expand the Schema Attributes section and change Alias Mode to Expose Aliases as Metadata Attributes.
By exposing the aliases as metadata, a <name>_alias attribute will be added to the incoming data. This attribute stores the alias value for the corresponding attribute. Click OK twice to add the reader.
2. Alter Alias Values
Next, we want to modify the alias values. Add an AttributeManager to the canvas and connect it to the Community Centres reader feature type.
In the AttributeManager parameters, simply type in the <name>_alias attributes you wish to change under Output Attribute and set the Attribute Value to contain the altered value you wish to write to the destination alias definition. Enter the following attributes:
-
Output Attribute: CentreName_alias
- Attribute Value: Name
-
Output Attribute: CentreAddress_alias
- Attribute Value: Address
-
Output Attribute: CentreURL_alias
- Attribute Value: URL
Click OK
Feature Class alias: you can also set the feature class alias. Set the format attribute geodb_feature_class_alias to the alias name.
3. Write Alias Values to Destination Geodatabase
Now we can write out the data. Add a writer to the canvas and set the following:
- Format: Esri Geodatabase (File Geodb)
-
Dataset: <path>\Vancouver.gdb
- Click on the ellipses to navigate to a location on your computer
- Feature Class or Table Definition: Copy from Reader
Click OK.
Once the writer feature type is added to the canvas, connect it to the AttributeManager.
As an optional step, if you wish to write the Community Centres data to a feature dataset, open the writer feature type parameters, and under Table Creation Parameters, type "Community" for Feature Dataset.
4. Save and Run the Workspace
Save and run your workspace. You can view the new alias names in ArcMap.
Advanced
FME can create attribute aliases for features read into the workspace that lack aliases. This is possible if there is an additional attribute with the same name as the original attribute, suffixed with _alias. The value of that attribute will be used as the alias on table creation.
For example, there is an attribute named CentreAddress, and another named CentreAddress_alias with a value of Address. The value of CentreAddresses_alias will serve as the alias for CentreAddress (alias: Address). This only needs to occur on the first feature.
Data Attribution
The data used here originates from open data made available by the City of Vancouver, British Columbia. It contains information licensed under the Open Government License - Vancouver.