Expressions are used to format column content into column content details for the display. It is also possible to summarize the content of several columns for the display (for example, coordinates).
The $ sign is used to reference a particular expression to calculate a field display.
Reference to the field in the form, in which the computed value is displayed, occurs via @ in the locales section. The field does not necessarily have to exist in the database to be displayed in the attribute form as a field.
In the schema section of the configuration attribute form, it can look like this:
"fields" : [
{
"name" : "Expression_ShapeLength",
"title" : "@Field_Expression_ShapeLength_Title",
"expression" : "{$Expression_ShapeLength}",
"readonly" : true
}
]
In this chapter, the syntax of the callable expression defined in the "expressions" section of the definition form is described. For the syntax of the displayed field value, see the "Database columns title and tooltip) chapter
Syntax VertiGIS models: for "expressions"
Expression_{domain_}field
Part of the name |
Values |
Expression |
Fixed text |
domain |
Optional. Name of the domain (WAT, GAS, ELE, SEW, DHC, CCP, structure). Must only be used if the display per domain or even just for one domain should be different. Upper/lower case: the domain name is written as it is defined in the database. |
field |
If only one column is handled in the expression, the column name is used. The column name is always specified in lower case because writing in upper and lower case varies according to database type. If several columns are handled (coordinates), it would make sense to incorporate both column designations. If, however, these are too long, free descriptive text can be used. |
Examples:
•"Expression_ShapeArea" : "Text(Area($feature, 'square-meters'), '#.###')",
•"Expression_XYCoordinate": "Text(Geometry($feature).x, '#.##')+' / '+Text(Geometry($feature).y, '#.##')",
•"Expression_supportedsubnetworkname": "Text(Replace($feature.supportedsubnetworkname, '::', TextFormatting.NewLine))"
