In UBIK®, a Metaproperty describes a single feature of a certain Metaclass. A Metaproperty will never hold own values, but it serves as a definition for a resulting BaseProperty on a derived ContentClass.
For enhanced reuse, MetaProperties can be organized in a Pool and linked to many MetaClasses, using the Systemrelation MetaProperty
- 1 Data Types
- 2 Configuration
- 2.1 String Length
- 2.2 Multilanguage
- 2.3 Reference
- 2.4 Selective List
- 2.5 Unit Item
- 2.6 Format
- 2.7 Value Validation
- 2.8 Meta Attribute
- 2.9 Default value
- 2.10 Initial value
- 2.11 Index Keys
- 2.12 Index Count
- 2.13 Index Type
- 2.14 Bytestream Type
- 2.15 Order
- 2.16 Serialize
- 2.17 Category
- 3 Editing a MetaProperty
- 4 Released To LiveMode
- 5 See also
A MetaProperty needs to have a data type that determines which kind of data should be stored in it. The following data types are currently supported by UBIK®:
Default value; will result in an error when attempting to set values.
A boolean value that can be either True or false
A serialized stream of bytes, non human readable.
A compressed text value, typically used to store texts with lots of white spaces and formatting information, such as source code.
Date and time in a combined value, where the actual format is depending on the cultural/regional settings of the machine.
A pointer to another object, represented with the GUID of the target object.
A discrete integer number.
A string value.
Markup text in XML format.
A ByteStream representing a Signature.
A MetaProperty can be configured with various additional options which are described in the following.
The maximum number of characters for a property value. Only applies to property types that store text values, like
If set to true, the property will store values in all configured languages. Only applies to properties of type Text.
The Selective List to pick values from instead of providing free input of values.
The format how a numeric value should be displayed. Only applies to properties of type floating point. Some examples:
- #.### will result in a number with a maximum of 3 digits right of the decimal point
- #.0 will result in a number with a 0 or one digit right of the decimal point
For a full list of formatting options please refer to Microsoft's documentation about
For a file reference property, a list of supported file extensions can be supplied so that the file selection on the client is constrained to certain file types.
Example: the format string *.xls; *.xlsx will allow allow selection of Excel files on the client for this property.
For a text/string property, a format string can be used to limit the number of characters client users are allowed to enter.
- To specify a lower bound, use e.g.
Lengthwhich requires a text input of at least 10 characters;
- To specify a lower bound and an upper bound, use e.g.
Length[10;20]which requires a text input of 10 to 20 characters.
Provide absolute lower and upper limits as well as a warning scope for the property values. The system evaluates the configured validation object as
- Value will be discarded if it exceeds lower or upper limits
- Input field will be marked with a yellow border if the value is within the warning boundaries
If an Attribute object has been set the system will automatically store extended information for a property value, for example a validation time stamp.
The default value of a MetaProperty defines which value will be displayed on the client by a property if it doesn't have an own value set.
The initial value of a MetaProperty defines which value will be set to the property initially when a new instance of it is created. This can be a constant value, or an Offline Expression that is evaluated on the client. Once the value is changed, the initial value is lost for this instance.
Enter the index keys as a comma separated list of strings, for example "a,b,c,d" (INDEXCOUNT = 4).
Set the number of named index keys, for example to 4.
Defines how the data is serialized in the database, possbile types are
- Text (string) [but which is not supported by subsequent features yet]
Defines the ordering of the MetaProperty with an integer number in ascending order, so the lowest number will be first in order.
If true, the value of the property will be serialized when it is set or changed.
The category the property shall be assigned to. This is used for grouping purposes in various UI elements, where properties of the same assigned category will be displayed together.
Editing a MetaProperty
Once a MetaProperty is used on a single MetaClass editing of properties is restricted to properties that may not effect data validity. The System uses a Rule to validate the edited properties and creates a RuleViolation whenever a "locked" property is edited. Following properties may not be changed/edited for a "used" MetaProperty:
Released To LiveMode
A MetaProperty is marked as released to live mode when:
- It is used on at least one MetaClass which is already released.
- It is referenced by at least one PoolMetaProperty which is used on at least one MetaClass which is already released.
Editing a released MetaProperty is restricted to properties that have no effect on the released table structure. The System uses a Rule to validate the edited properties and creates a RuleViolation whenever a "locked" property is edited. Following properties may not be changed/edited for a released MetaProperty: