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Metadata Properties

The data manager's property registry registers the name, type, and an optional default value for standard metadata properties. Metadata properties can be defined at document, table and column level.

Overview

Only the definitions of the properties are stored in the data property registry. The actual property values are stored in objects of the property class corresponding to of the metadata level. For the column metadata level, the property class is DataColumnProperties.

Property Naming

There are a number of predefined, standard metadata properties for each property class, but custom properties may be added. Since the name of a property is used as an identifier, it must be unique within its property class. The name of a custom property must be qualified with a namespace prefix, such as Acme., where the dot marks the end of the prefix. All names without a prefix are reserved, as is the Spotfire. prefix.

Property Types

Since the type is part of a metadata property definition, all occurrences of a property must have values of the same type. The supported value types for metadata properties are the same as the data types used in columns, but they are more general, since lists of the standard types are supported. In addition, a column metadata property may also have an inherited type. This means the metadata property has the same type as the column values. The MinValue property is an example of where an inherited type is useful.

Column Properties

Column properties are by far the most widely used property class. There are four kinds of column property values:

  • Assigned property values: These are property values that have been set at the column node level, and which are therefore part of the document and saved to file. An assigned property value has the highest priority.
  • Imported property values An imported property value originates from a data source. It can be overridden by an assigned property and it is not stored on file if linked data is used.
  • Default property values Default values are optional, but can be defined in the data property registry. They are used only if neither an assigned value nor an imported value is available.
  • Calculated property values The calculated column properties are distinct from the previous three categories. A calculated property value is based on the content of the column and cannot be overridden.