Showing posts with label ObjectSpace. Show all posts

Wednesday, April 11, 2018

Access XAF Application Data in a non-XAF Application

In certain scenarios, you may need to create an axillary application for database maintenance and use Object Space to query your primary XAF application data. This topic describes how you can create and use Object Space in a regular non-XAF application.

Important

We do not recommend using the approach described here in XAF applications. Instead, always use the XafApplication.CreateObjectSpace method or access an existing Object Space.

In a non-XAF application, you have no XafApplication object to create an Object Space. But, an XafApplication does not create Object Spaces itself. Internally, it uses the Object Space Provider designed to create Object Spaces for the currently used ORM and those registered in its overridden XafApplication.CreateDefaultObjectSpaceProvider method. In a non-XAF application, you can instantiate the Object Space Provider manually. In XPO-based applications, use the DevExpress.ExpressApp.Xpo.XPObjectSpaceProvider constructor for this purpose. In Entity Framework applications, use the DevExpress.ExpressApp.EF.EFObjectSpaceProvider. Then, you can call the provider's CreateObjectSpace method to create an Object Space.

Entity Framework Example

You can use the following code to access data of the EFDemo application (typically installed to %PUBLIC%\Documents\DevExpress Demos 17.2\Components\eXpressApp Framework\EFDemoCodeFirst) and write the list of Departments to the standard output stream.

using DevExpress.ExpressApp.EF;
using DevExpress.ExpressApp;
using EFDemo.Module.Data;
// ... 
class Program {
    static void Main(string[] args) {
        EFObjectSpaceProvider osProvider = new EFObjectSpaceProvider(typeof(EFDemoDbContext),
            "integrated security=True;multipleactiveresultsets=True;data source=(localdb)\\v11.0;initial catalog=EFDemo_17.2");
        IObjectSpace objectSpace = osProvider.CreateObjectSpace();
        foreach (Department department in objectSpace.GetObjects()) {
           Console.WriteLine(department.Title + "\t" + department.Office);
        }
    }
}

XPO Example

In XPO-based applications, you should additionally initialize the Types Info Subsystem. The following example demonstrates how to access data of the MainDemo application (typically installed to %PUBLIC%\Documents\DevExpress Demos 17.2\Components\eXpressApp Framework\MainDemo) and write the list of Departments to the standard output stream:

using DevExpress.ExpressApp.Xpo;
using DevExpress.ExpressApp;
using MainDemo.Module.BusinessObjects;
// ... 
class Program {
    static void Main(string[] args) {
        XpoTypesInfoHelper.GetXpoTypeInfoSource();
        XafTypesInfo.Instance.RegisterEntity(typeof(Department));
        XPObjectSpaceProvider osProvider = new XPObjectSpaceProvider(
        @"integrated security=SSPI;pooling=false;data source=(localdb)\v11.0;initial catalog=MainDemo_17.2", null);
        IObjectSpace objectSpace = osProvider.CreateObjectSpace();
        foreach (Department department in objectSpace.GetObjects()) {
            Console.WriteLine(department.Title + "\t" + department.Office);
        }
    }
}

If you need to populate the database with initial data, use the DatabaseUpdater.Update method as follows:

using DevExpress.ExpressApp.Updating;
// ... 
DatabaseUpdater databaseUpdater = new DatabaseUpdater(
    osProvider, new ModuleBase[0], "", osProvider.ModuleInfoType);
databaseUpdater.Update();

Ways to Implement Business Logic

There are two common places for your business logic code - Controllers and business classes themselves. In Controllers, you can declare new and customize existing Actions and handle other Controllers' events. In business classes, you can put logic into property getters and setters, implement methods that are triggered automatically when the object is created, loaded, saved and deleted (see IXafEntityObject) and declare action methods. In these cases, Object Space is required when data the current business object exposes is insufficient for your business logic, and you need to query more data. You may also use Object Space in your database initialization code, in complex View Items, etc. This topic describes the API you can use to get Object Space in various contexts.

Get an Existing Object Space

Usually, you can use an existing Object Space instance accessible via the XAF API. The following table describes how you can get an Object Space from various contexts of your code:

Context	Ways to Access Object Space	Examples
Business Object	An Object Space reference is automatically assigned to the IObjectSpaceLink.ObjectSpace property when a business object supporting an IObjectSpaceLink is instantiated. You can implement this interface and access other business objects directly in the current object code using the Object Space passed to the ObjectSpace property. If you additionally implement an IXafEntityObject, then you can place your logic into the IXafEntityObject.OnCreated, IXafEntityObject.OnLoaded and IXafEntityObject.OnSaving methods. You can use the XAF Business Object \| EF Business Object from Template Gallery to add a class that supports both IXafEntityObject and IObjectSpaceLink. We recommend using Controllers instead of accessing UI-related entities (Views, Controllers, Actions) and executing UI-specific logic within the business class code, because it violates the separation of concerns principle and is against the MVC architecture.	IXafEntityObject
Controller	In XAF applications, an Object Space is automatically assigned for each View. In a View Controller, you can get the current View using the ViewController.View property. Then, access the Object Space with the View.ObjectSpace. You can also use the protected ViewController.ObjectSpace property that refers to the same Object Space as View.ObjectSpace. A Window Controller does not expose a View directly. You can access the current Frame using the Controller.Frame property and get the View with Frame.View. A View handles Object Space events to update the UI each time an object changes. We recommend creating a new Object Space that is not bound to a current View instead of using theView.ObjectSpace property to process large amounts of data. You should also use a new Object Space when you create a new View with the XafApplication.CreateListView or XafApplication.CreateDetailView methods.	Add a Simple Action using an Attribute Add an Action that Displays a Pop-up Window Add an Action with Option Selection IObjectSpace.ObjectChanged
Module Updater	In a ModuleUpdater descendant, you can use the protected ModuleUpdater.ObjectSpace property to access the Object Space instance that can be used for database update operations. Do not use a new Object Space to update the database.	Supply Initial Data (EF) Supply Initial Data (XPO)
List Editor	A reference to the CollectionSourceBase object is automatically passed to the IComplexListEditor.Setup method if your custom List Editor supports the IComplexListEditor interface. You can implement this interface and access the Object Space via the CollectionSourceBase.ObjectSpace property.
View Item or Property Editor	A reference to an Object Space is automatically passed to the IComplexViewItem.Setup method if your custom View Item or Property Editor supports the IComplexViewItem interface. You can implement this interface and store the Object Space reference to a local variable for future use.	IComplexViewItem

Object Space is also available using arguments passed to various events of the XafApplication class.

Event	Object Space Parameter
XafApplication.CreateCustomCollectionSource	CreateCustomCollectionSourceEventArgs.ObjectSpace
XafApplication.CreateCustomLogonWindowObjectSpace	CreateCustomPropertyCollectionSourceEventArgs.ObjectSpace
XafApplication.CreateCustomPropertyCollectionSource	CreateCustomLogonWindowObjectSpaceEventArgs.ObjectSpace
XafApplication.ObjectSpaceCreated	ObjectSpaceCreatedEventArgs.ObjectSpace
XafApplication.ViewCreating	ViewCreatingEventArgs.ObjectSpace

Create a New Object Space

It is often necessary to instantiate a new Object Space (for example, when you create a View using the XafApplication.CreateListView or XafApplication.CreateDetailView methods). Use the XafApplication.CreateObjectSpace method instead of an Object Space constructor to create an Object Space. For instance, the Controller.Application property is available in a Controller context, and you can create an Object Space as follows:

IObjectSpace objectSpace = this.Application.CreateObjectSpace();

Refer to the XafApplication class description to see how to obtain an XafApplication instance in various contexts. You cannot create new Object Spaces in the business object context because an XafApplication instance is not available there.

Examples:

Important

You should manually dispose of an Object Space when you are finished using it if you do not assign it to a View. An Object Space associated with a View is removed automatically together with this View.

Once you have obtained or created an Object Space, you can use it to query or modify data (see Create, Read, Update and Delete Data).

Create, Read, Update and Delete Data

Once you have obtained or created an Object Space instance (as described in the Ways to Implement Business Logic topic), you can use it to create, read, update or delete data. This topic lists common data-aware operations with the corresponding Object Space methods and events.

Data Manipulation	Related IObjectSpace Members
Create a new object	Methods: IObjectSpace.CreateObject IObjectSpace.CreateObject IObjectSpace.IsNewObject
Get a single object	Methods: IObjectSpace.FindObject IObjectSpace.FindObject IObjectSpace.GetObject IObjectSpace.GetObjectByKey IObjectSpace.GetObjectByKey IObjectSpace.GetObjectByHandle IObjectSpace.IsObjectFitForCriteria
Get a collection	Methods: IObjectSpace.GetObjects IObjectSpace.GetObjects IObjectSpace.CreateDataView IObjectSpace.CreateServerCollection IObjectSpace.CreateCollection IObjectSpace.SetTopReturnedObjectsCount IObjectSpace.GetObjectsQuery
Count objects	Methods: IObjectSpace.GetObjectsCount
Save	Methods: IObjectSpace.CommitChanges IObjectSpace.IsObjectToSave IObjectSpace.GetObjectsToSave Properties: IObjectSpace.IsCommitting Events: IObjectSpace.Committing IObjectSpace.Committed IObjectSpace.CustomCommitChanges IObjectSpace.ObjectSaving IObjectSpace.ObjectSaved
Delete	Methods: IObjectSpace.Delete IObjectSpace.IsObjectToDelete IObjectSpace.GetObjectsToDelete Properties: IObjectSpace.IsDeleting Events: IObjectSpace.ObjectDeleting IObjectSpace.ObjectDeleted
Track modifications	Methods: IObjectSpace.SetModified Properties: IObjectSpace.ModifiedObjects IObjectSpace.IsModified Events: IObjectSpace.ObjectChanged IObjectSpace.ModifiedChanged IObjectSpace.ModifiedChanged
Refresh and rollback	Methods: IObjectSpace.Refresh IObjectSpace.ReloadObject IObjectSpace.Rollback Events: IObjectSpace.Refreshing IObjectSpace.Reloaded IObjectSpace.ObjectReloaded IObjectSpace.CustomRefresh IObjectSpace.RollingBack IObjectSpace.CustomRollBack

For details, refer to the descriptions of these members.

Saturday, March 17, 2018

ObjectSpace

BaseObjectSpace Members

A base class for the classes that implement the IObjectSpace interface.

Public Constructors

Show: Inherited

	Name	Description
	BaseObjectSpace	Creates a new instance of the BaseObjectSpace class.

Top

Public Properties

Show: Inherited

	Name	Description
	CanFilterByNonPersistentMembers	For internal use.
	Connection	Gets the connection to the underlying data source.
	Database	Gets the name of the database.
	IsCommitting	Indicates whether the Object Space is currently committing the changes made to its object(s).
	IsConnected	Indicates whether the BaseObjectSpace is connected to the database.
	IsDeleting	Indicates whether the current Object Space is about to delete an object(s).
	IsDisposed	Gets a value indicating whether an Object Space has been disposed of.
	IsModified	Specifies whether objects belonging to the current Object Space are modified.
	IsReloading	Gets a boolean value indicating whether or not the Object Space is reloading.
	LockingCheckEnabled	Specifies whether or not the additional locking check is performed.
	ModifiedObjects	Returns a collection of objects that have been created, modified or deleted in the current object context.
	NonPersistentChangesEnabled	Specifies whether the BaseObjectSpace is marked as modified (see IsModified) when a non-persistent property is changed.
	Owner	Specifies the View owning the current Object Space.
	TypesInfo	Gets information on the business classes added to the Application Model (see IModelBOModel).

Top

Public Methods

Show: Inherited

	Name	Description
	ApplyCriteria	Filters a particular collection on the server side.
	ApplyFilter	Filters a particular collection on the client side.
	CanApplyCriteria	Indicates whether collections of a particular type can be filtered on the server side.
	CanApplyFilter	Indicates whether a particular collection can be filtered on the client side.
	CanInstantiate	Indicates whether instances of a particular type can be created.
	CommitChanges	Saves all the changes made to the persistent objects belonging to the current Object Space to the database.
	Contains	Indicates whether a specified object belongs to the current Object Space.
	ConvertExpressionsStringToExpressionsList	Returns the list of DataViewExpression objects converted from the passed semicolon-separated expressions list.
	ConvertSortingToString	Returns the string representation of a given sort list.
	ConvertStringToSorting	Converts the sorting string into the sorting list.
	CreateCollection	Overloaded. Creates and initializes a collection of objects of the specified type.
	CreateDataView	Overloaded. Returns a list of data records retrieved from a database without loading complete business classes (a data view). Values in each data record can be obtained from specific business class properties directly, or be evaluated by the database server using complex expressions.
	CreateInstantFeedbackCollection
	CreateNestedObjectSpace	Creates a nested Object Space.
	CreateObject	Creates an object of the specified type.
	CreateObject	Creates an object of the type designated by the specified generic type parameter.
	CreateParseCriteriaScope	Used when parsing a CriteriaOperator represented by a string and containing persistent objects.
	CreateServerCollection	Creates and initializes a new instance of the EFServerCollection or DevExpress.Xpo.XPServerCollectionSource class with criteria-specific options.
	Delete	Overloaded. Marks the specified persistent object and its aggregated objects as deleted from persistent storage.
	Dispose	Releases all resources used by an BaseObjectSpace object.
	EnableObjectDeletionOnRemove	Enables/disables the deletion of persistent objects from the data source when they are removed from the specified collection.
	Equals	Determines whether the specified System.Object instances are considered equal. (Inherited from System.Object)
	Equals	Determines whether the specified System.Object is equal to the current System.Object. (Inherited from System.Object)
	Evaluate	Evaluates the specified criteria for business objects of the given type.
	FindObject	Overloaded. Searches for the first object of the specified type, matching the specified criteria.
	FindObject	Overloaded. Searches for the first object of the type designated by the specified generic type parameter, matching the specified criteria.
	GetAssociatedCollectionCriteria	Returns the criteria applied to a specific object's associated collection property.
	GetCollectionObjectType
	GetCollectionSorting	Returns the sort settings for a particular collection.
	GetCriteria	Returns the criteria used to filter a particular collection on the server side.
	GetDisplayableProperties	Gets the properties considered visible by the specified collection.
	GetEvaluatorContextDescriptor	Creates an instance of the EvaluatorContextDescriptor that is used to supply metadata on the specified type to the ExpressionEvaluator objects.
	GetExpressionEvaluator	Overloaded. Creates an ExpressionEvaluator object that is used to evaluate whether objects of the specified type satisfy a particular criteria.
	GetFilter	Returns the criteria used to filter a particular collection on the client side.
	GetHashCode	Serves as a hash function for a particular type. System.Object.GetHashCode is suitable for use in hashing algorithms and data structures like a hash table. (Inherited from System.Object)
	GetIntermediateObjectReferences	For internal use.
	GetKeyPropertyName	Gets the name of the specified type's key property.
	GetKeyPropertyType	Gets the key property type of the specified business type.
	GetKeyValue	Overloaded. Returns the key property's value of the specified object.
	GetKeyValue	Overloaded. Returns the key property's value of the specified persistent object.
	GetKeyValueAsString	Overloaded. Returns the key property's value of the specified object, converted to a string representation.
	GetKeyValueAsString	Overloaded.
	GetObject	Retrieves an object that corresponds to a specific object from another Object Space or to a specific record from a data view created by the IObjectSpace.CreateDataView method.
	GetObject	Retrieves an object from another Object Space to the current Object Space. The returned object is cast by the type designated by the specified generic type parameter.
	GetObjectByHandle	Returns the object with the specified handle.
	GetObjectByKey	Returns the persistent object that has the specified value for its key property.
	GetObjectByKey	Returns a persistent object of the type designated by the specified generic type parameter, with the specified value for its key property.
	GetObjectHandle	Returns an object's handle.
	GetObjectKey	Converts the key property value string representation into its actual type.
	GetObjects	Overloaded. Returns an IList collection of objects of the specified type, retrieved to the current Object Space and filtered according to the specified criteria.
	GetObjects	Overloaded. Returns an IList collection of objects of the specified type, retrieved to the current Object Space and filtered according to the specified criteria.
	GetObjectsCount	Returns the number of objects specified.
	GetObjectsCriteria	Constructs a criteria that can be used to select the specified list of business objects.
	GetObjectsQuery	Gets a queryable data structure that provides functionality to evaluate queries against a specific business object type.
	GetObjectsToDelete	Returns a collection of persistent objects that will be deleted when the current transaction is committed, including objects that will be deleted in the parent transaction(s), optionally.
	GetObjectsToSave	Returns a collection of persistent objects that will be saved when the current transaction is committed, including objects that will be saved in the parent transaction(s), optionally.
	GetObjectType	Returns the type of the specified business object.
	GetTopReturnedObjectsCount	Returns the maximum number of objects to be retrieved by the specified collection from a data store.
	GetType	Gets the System.Type of the current instance. (Inherited from System.Object)
	IsCollectionLoaded	Indicates whether a particular collection is loaded with objects from the database.
	IsDeletedObject	Indicates whether the specified persistent object is deleted from the database.
	IsDeletionDeferredType	Returns a value that indicates if the deferred deletion is enabled for persistent objects of a given type.
	IsDisposedObject	Determines whether an object has been disposed of.
	IsIntermediateObject	For internal use.
	IsKnownType	Returns the boolean value indicating whether or not the specified type is known by the BaseObjectSpace.
	IsNewObject	Indicates whether a specified object has been created but has not been saved to the database.
	IsObjectDeletionOnRemoveEnabled	Indicates whether the deletion of persistent objects from the data source when they are removed from the specified collection is enabled.
	IsObjectFitForCriteria	Overloaded. Specifies whether a particular object satisfies the specified criteria.
	IsObjectToDelete	Indicates whether the specified object has been deleted but not committed in the current object context or the transaction currently in progress.
	IsObjectToSave	Indicates whether the specified object has been added, deleted or modified, but not committed in the current object context or the transaction currently in progress.
	ObjectKeyValuesEqual
	ParseCriteria	Tries to convert the specified string representation of an expression to its DevExpress.Data.Filtering.CriteriaOperator equivalent.
	ReferenceEquals	Determines whether the specified System.Object instances are the same instance. (Inherited from System.Object)
	Refresh	Updates the persistent objects belonging to the current Object Space.
	ReloadCollection	Clears the specified collection.
	ReloadObject	Updates the specified object in the current Object Space with data from the data source.
	RemoveFromModifiedObjects	Removes the specified object from the object context or the list of objects to be committed.
	Rollback	Cancels the changes made to the persistent objects belonging to the current Object Space.
	SetCollectionSorting	Applies the specified sorting to a given collection.
	SetDisplayableProperties	Changes the properties considered visible by a particular collection.
	SetModified	Overloaded. Sets the state of the specified object to be Modified.
	SetPrefetchPropertyNames
	SetTopReturnedObjectsCount	Sets the maximum number of objects that can be retrieved from the specified collection in a data store.
	ToString	Returns a System.String that represents the current System.Object. (Inherited from System.Object)

Top

Public Fields

Show: Inherited

	Name	Description
	CompositeKeyPropertyType

Top

Public Events

Show: Inherited

	Name	Description
	Committed	Raised after saving changes made to persistent objects belonging to the current Object Space to the database.
	Committing	Occurs before saving the persistent objects belonging to the current Object Space to the database.
	ConfirmationRequired	Occurs when performing refresh or rollback operations with the current Object Space's persistent objects.
	Connected	Occurs after a connection to a database has been established.
	CustomCommitChanges	Replaces the default process for committing changes made to persistent objects with a custom one.
	CustomDeleteObjects	Occurs to replace the default process of deleting persistent objects with a custom one.
	CustomRefresh	Occurs to replace the default process of refreshing persistent objects with a custom one.
	CustomRollBack	Occurs to replace the default process of persistent objects rollback with a custom one.
	Disposed	Occurs before an Object Space is disposed of.
	ModifiedChanged	Occurs when the current Object Space's IsModified state is changed.
	ObjectChanged	Raised when a persistent object is created, changed or deleted.
	ObjectDeleted	Occurs after the specified objects have been deleted.
	ObjectDeleting	Occurs when the specified objects are about to be deleted.
	ObjectEndEdit	Occurs after ending an edit operation taking place on the specified object.
	ObjectReloaded	Occurs after an object has been reloaded from the database.
	ObjectSaved	Occurs after saving changes made to a specified persistent object to the database.
	ObjectSaving	Raised before saving changes made to a specified persistent object to the database.
	Refreshing	Occurs before refreshing the current Object Space's persistent objects.
	Reloaded	Occurs when the Rollback or Refresh method is called.
	RollingBack	Occurs before rolling back the changes made to the current Object Space's persistent objects.

Top

FXFE

Wednesday, April 11, 2018

Access XAF Application Data in a non-XAF Application

Access XAF Application Data in a non-XAF Application

Entity Framework Example

XPO Example

See Also

XAF implement Business Logic using ObjectSpace

Ways to Implement Business Logic

Get an Existing Object Space

Create a New Object Space

See Also

ObjectSpace CRUD

Create, Read, Update and Delete Data

See Also

Saturday, March 17, 2018

ObjectSpace

BaseObjectSpace Members

Public Constructors

Public Properties

Public Methods

Public Fields

Public Events

See Also