MicroStation CONNECT Item Types

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Introduction

This article provides a brief overview of Item Types technology in MicroStation CONNECT

The information presented here is an informal guide to Item Types. Its intended audience includes MicroStation administrators and MicroStation developers.

Feature Table

There's a useful table in MicroStation CONNECT help that compares various annotation technologies, including Item Types and Text Fields. To find this table in MicroStation help, search for Comparing Text Field, Label, Note, Table, Report, Item, Item Type, and Item Sets.

MicroStation CONNECT help is available on line. Here's that comparison table in MicroStation Help.

Item Sets

To dispel confusion, Item Sets are an earlier and different technology. They are unrelated to Item Types other than having a similar name.

Item Types

Item Types, introduced with MicroStation CONNECT, are meta data that define data types. In other words, a schema. Item Types are not graphic elements; rather, they represent a MicroStation capability for storing structured alpha-numeric data. Bentley Systems terminology for data stored in Item Types includes 'business data' and 'EC Schema data'.

The foundation of Item Types is the ECSchema

• Item Types define data, not graphics
• A graphic element can be associated with Item Type data
  • MicroStation CONNECT provides tools to enable a user to make that association
• A text field can link to Item Type data
  • Hence text elements, labels and notes can display Item Type data
• Item Types are a possible data source for Reports, new to MicroStation CONNECT
  • Reports are the precursor for Tables, also new to MicroStation CONNECT

Item Types are meta data that define data types. In other words, a schema. Item Types were not available in versions of MicroStation prior to CONNECT.

Each Item Type has a name and a number of properties. Each property has a name and a data type (e.g. Text, Integer, Number) …

Item Type and ECSchema Property Monikers

Item Type Property Monikers

Moniker	Comment
Name	Human readable and machine readable.  Visible in the UI
Internal Name	Machine-readable version of Name.  Non-ASCII characters are translated to Unicode.  Not normally visible in the UI

Unfortunately, an Item Type property does not have a DisplayLabel, which most other ECSchema objects have …

EC Schema Monikers

Moniker	Comment
DisplayLabel	Human readable, not intended for machine consumption. Not available for Item Type properties

Item Type add Business Data to your DGN Elements

Item Types are not graphic elements; rather, they represent a MicroStation capability for storing structured alpha-numeric data on an object. Item data can be attached to an element, DGN model or DGN file. Bentley Systems terminology for data stored in Item Types includes 'business data' and 'EC Schema data'.

• Item Types define data, not graphics
• A graphic element can be associated with Item Type data
  • MicroStation CONNECT provides tools to enable a user to make that association
• A text field can link to Item Type data
  • Hence text elements, labels and notes can display Item Type data
• Item Types are the data source for Reports, new to MicroStation CONNECT
  • Reports are the precursor for Tables, also new to MicroStation CONNECT

Item Types provide a simplified way for users and applications to create, manage, and use EC data within DgnFiles.

An Item Type is an ECClass which supports a subset of the features available to ECClasses. In comparison to full-fledged ECClasses, Item Types:

• Do not support inheritance
• Provide a default value for every primitive property
• Do not support most custom attributes
• Support only a portion of available property types CustomProperty::Type
• Can be used by Item Type-based tools, such as MicroStation's Attach Item tool

Item Types are stored an Item Type Library, which is a similarly restricted ECSchema. In comparison to full-fledged ECSchemas, Item Type Libraries:

• Can reference only standard schemas (chiefly for custom attributes)
• Do not support most custom attributes
• Cannot define custom attribute classes
• Can be freely modified, deleted, updated, and renamed by the user

An Item Type Library is a resource, stored in a DGN file. Typically they are managed by defining the Item Type and its properties in a DGNLib, which is made available to all users who need to use that Item Type. A management dialog is provided by MicroStation for the end user …

• An Item Type Library is identified by its name (usually provided by the user)
• A DgnFile which uses an Item Type Library stores a copy of that library locally
• A local Item Type Library can be replaced with an updated version from a dgnlib
• When copying elements between files, if the element references an Item Type Library, it will be remapped to use an existing Item Type Library by the same name in the destination file; or else the Item Type Library will be copied into the destination file.

Item Types are metadata. They become useful when they are "attached" to a host to produce an Item. An Item is an ECInstance of an Item Type ECClass.

New to MicroStation CONNECT Update 16

From MicroStation CONNECT Update 16 Reports implement Aggregates in report definitions.

New to MicroStation CONNECT Update 15

From MicroStation CONNECT Update 15 Item Types permit Expressions in property definitions. An Expression can compose data from several sources.

New to MicroStation CONNECT Update 10

From MicroStation CONNECT Update 10 Item Types are supported by MicroStation VBA.

MicroStation CONNECT Update 10 introduces the Picklist. A Picklist is a user-defined list of possible values for an Item property.

For example, suppose you want to annotate door cells with your Item Type. One property of your Item Type is door-type. You would like to restrict the value of the door-type property to internal door, internal fire door, external door and fire escape door. A Picklist enables you to constrain what the user can assign to your Item's door-type property.

MicroStation CONNECT Update 7

MicroStation CONNECT Update 7 introduced the Edit Item Dialog.

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Reports

MicroStation CONNECT introduced Reports. Reports is an analytic tool. It extracts alphanumeric data (business data) from your DGN file, model, elements or elsewhere. When Item Types are in use, Reports can extract Item instance data attached to your DGN model or elements.

Visit the reports page for more information, and to see an example of Reports in action.

Programmer's Notes

Item Types is the term used in user documentation. The MicroStationAPI and DgnPlatformNet APIs uses terms such as CustomPropertyContainer.

VBA support for Item Types arrived with MicroStation CONNECT Update 10. See the following class descriptions in VBA help …

• ItemType
• ItemTypeProperty
• ItemTypePropertyHandler
• ItemTypeLibrary
• ItemTypeLibrary

AreaAnnotator™

This article about AreaAnnotator CONNECT Edition™ shows how Item Types help obtain reports about area features in a DGN model.

Contributors

I am indebted to Bentley Systems staff member Paul Connelly and to Be Communities MVP Jan Slegr. Both have contributed both factual information about Item Types and EC Schemas as well as their interpretation of how they can be used. They contribute enthusiastically to the MicroStation Programming Forum.

EC Schemas

EC Schemas were introduced with MicroStation V8i and are continued in MicroStation CONNECT. They are the foundation of Item Types introduced with MicroStation CONNECT. You can read more about ECSchemas.

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Item Sets

We don't discuss Item Sets here in any detail. We mention them because of the similarity in their name to Item Types. Item Sets were introduced with MicroStation V8i. Item Sets are unrelated to Item Types.

• Item Sets are a superset of MicroStation Named Groups
• They have searching and filtering tools
• They can be associated with EC Schema Data
• Item Sets are not a data source that can be used by labels or notes via text fields