Hi @vzhang188 ,
Creating a set of dependent dropdown fields (Location, Building, Room) using a lookup select box variable type, where each subsequent field's options are filtered based on the preceding selection, typically involves the following steps:
Define your Data Source:
- Create a data source (e.g., a custom table, a database view) that contains the relationships between Location, Building, and Room. This data source should have columns for each level of the dependency.
- For example, a table could have columns like location_name, building_name, and room_number, with multiple rows for each location and its associated buildings and rooms.
Create the "Location" Lookup Select Box:
- Create a variable of type "Lookup Select Box" for "Location."
- Configure its "Lookup from table" to point to your data source.
- Set "Lookup value field" to the column containing the location names (e.g., location_name).
- Set "Lookup label field" to the same column (e.g., location_name).
Create the "Building" Lookup Select Box:
- Create another "Lookup Select Box" variable for "Building."
- Point its "Lookup from table" to your data source.
- Set "Lookup value field" to the column containing building names (e.g., building_name).
- Set "Lookup label field" to the same column (e.g., building_name).
- Crucially, add a "Reference qualifier" to this variable. This qualifier will filter the buildings based on the selected location. The qualifier would typically look something like this:
Code:
location_name={{location_variable_name}}
Replace location_variable_name with the actual name of your "Location" variable.
Create the "Room" Lookup Select Box:
- Create a third "Lookup Select Box" variable for "Room."
- Point its "Lookup from table" to your data source.
- Set "Lookup value field" to the column containing room numbers (e.g., room_number).
- Set "Lookup label field" to the same column (e.g., room_number).
- Add a "Reference qualifier" to this variable: to filter rooms based on both selected location and building:
Code:
location_name={{location_variable_name}}^building_name={{building_variable_name}}
Replace location_variable_name and building_variable_name with the actual names of your "Location" and "Building" variables.
Important Considerations:
Variable Names: Ensure the variable names used in the reference qualifiers exactly match the names of your lookup select box variables.
Data Consistency: The data in your source table must be consistent for the filtering to work correctly (e.g., building names should be consistently linked to their respective locations).
Performance: For very large datasets, optimize your data source and reference qualifiers to ensure good performance.
User Interface: The platform handling these variables (e.g., a service catalog in ServiceNow) will automatically refresh the options in dependent dropdowns when a selection is made in the preceding one.
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