Fields in a View

Every view has a set of fields associated with it. Each field in a view is identified by its field name and its field spec (specification). The field names are the names that a Maptitude user sees in the column headings of a dataview and in the drop-down lists that appear in the various dialog boxes. The field specs are strings that include both the view name and the field name. The following GISDK functions get information on the field names and field specs for a view:

 

GISDK Function	Summary
GetEditableFields()	Gets a list of the editable fields in a view
GetField()	Returns the view, field name, and field spec for a field
GetFieldFullSpec()	Returns a full field spec for a field name
GetFieldInfo()	Returns the data type, display width, decimals, and index flag for a field
GetFields()	Gets a list of the fields in a view
GetFieldTableType()	Gets the data type of a field in tables and joined views
GetFieldType()	Gets the data type of a field
GetIDField()	Gets the full field spec of the ID field for a layer
GetReadOnlyFields()	Gets a list of the read-only fields in a view

 

Here is an example of the difference between field names and field specs. If you open a dBASE file with three fields (Name, Population, and Income) to create a view named States, GetFields() returns these two lists:

 

Field Name	Field Spec
Name	States.Name
Population	States.Population
Income	States.Income

 

Maptitude guarantees that there will be no duplicates in either of the two lists, by modifying the field names or field specs as needed.

 

Suppose you join two dBASE files (File1 and File2) to create a joined view named File1+File2. File1 contains three fields: Name, Pop80, Income80, and File2 contains three fields: Name, Pop90, and Income90. If you call GetFields() on the joined view, it returns the following two lists:

 

Field Name	Fields Spec	Note
File1.Name	File1+File2.File1.Name	Field name modified
Pop80	File1+File2.Pop80
Income80	File1+File2.Income80
File2.Name	File1+File2.File2.Name	Field name modified
Pop90	File1+File2.Pop90
Income90	File1+File2.Income90

 

Some GISDK functions require field names, and others require field specs. You must be careful to pass the correct field identifier to these GISDK functions.

 

The following GISDK functions get and set field sets for a Standard Caliper Geographic file:

 

GISDK Function	Summary
GetFieldSets()	Gets the field sets for a Standard Caliper Geographic file
SetFieldSets()	Sets the field sets for a Standard Caliper Geographic file

 

For more information, see "Creating and Using Field Sets" in the Maptitude program online help.