MetaType class

5 min

MetaType includes common types, and you can extend it with UI-friendly types. For example, instead of using one type of string, Business Meta-Model has Short String, Long String, HTML, Email, Phone and number. You can create a new MetaType based on system type or create a custom one.

Business Foundation (BF) lets you use a number of different meta types for your .NET applications. You can use the included meta-types or implement a custom meta-type.

Default meta-types

Call the RegisteredTypes property of the MetaClassManager class to get all registered meta-types. The following table shows ready-to-use BF meta-types in Name (system type) – description.

Guid (Guid) – A globally unique identifier (GUID).

DateTime (DateTime) – An instant in time, typically expressed as a date and time of day.

Date (DateTime) – An instant in date.

Integer (Integer) – A 32-bit signed integer.

Float (Double) – A double-precision floating-point number.

Currency (Currency) – A currency number.

CheckboxBoolean (Boolean) – A Boolean value with check box.

DropDownBoolean (Boolean) – A Boolean value with drop-down.

Text (String) – Text of fixed length. Maximum length is 4096 chars.

EMail (String) – An e-mail string.

Url (String) – A URL string.

LongText (String) – A long text.

Html (String) – An HTML string.

File (File) – A file (name, length, content type, stream).

Image (File) – An image file.

IntegerPercent (Integer) – A 32-bit signed integer percent.

FloatPercent (Double) – A double-precision floating-point percent.

Duration (Integer) – A 32-bit signed integer duration value.

Create a meta type based on system type

You can create a new meta-type based on system type. You can find a complete list of system types in the McDataType enumerators.

To create a meta-type, such as Geolocation based on the String system type, open the edit scope and add a new MetaFieldType object to the MetaClassManager.RegisteredTypes collection.

The following example creates a Geolocation meta-type based on the String system type:

// Open Meta model edit scope
using (MetaClassManagerEditScope scope = DataContext.Current.MetaModel.BeginEdit())
  {
    // Add a new meta type
    MetaFieldType geoLocation = new MetaFieldType("Geolocation", "Geolocation", McDataType.String);
    DataContext.Current.MetaModel.RegisteredTypes.Add(geoLocation);
    // Save Changes
    scope.SaveChanges();
  }

Or, add a new record to the mcmd_MetaFieldType table and restart the application.

INSERT INTO mcmd_MetaFieldType ([Name], [FriendlyName], [McDataType]) 
   VALUES ('Geolocation', 'Geolocation', 6)

After registration, you can add a geolocation field to the meta-class. Using the meta-type name, you can load a new geolocation view and edit the UI control.

Create a custom meta type

When implementing a custom meta-type, you need to create the Meta-field installer and Meta-field property binder. When you create a meta-field, BF calls the meta-field installer to process meta-field into SQL columns. When you load an entity object, BF calls the meta-object property binder to convert values from an SQL column to a meta-field value.

To create a custom Meta-field installer, you create a class that implements the IMetaFieldInstaller interface, and implement the following methods.

IMetaFieldInstaller interface methods

AssignDataSource – Create a new columns in the SQL database from meta-field

AssignValidators – Assign default validators

UpdateDataSource – Update SQL columns from updated meta-field

UpdateValidators – Update validators

RemoveDataSource – Remove columns from SQL database

RemoveValidators – Remove validators

To create a custom Meta-object property binder, create a class that implements the IMetaObjectPropertyBinder interface, and implement the following methods.

IMetaObjectPropertyBinder interface methods

PreLoad – Load value from SQL row and save to meta field property.

PostLoad – Fill properties by other.

PreSave – Save value to SQL row.

PostSave – Fill properties by other.

Delete – Clean up if meta field is removing.

InitTableConfig – Initialize additional SQL relations. You should register the custom meta-field installer and meta-object property binder in the appsettings.json Commerce section.

"Commerce": {
  "MetaObjectTypeOptions": {
    "Types": [{
      "Name": "CustomType",
      "Installer": "",
      "Binder": ""
    }]
  }
}