Package.GetRelationshipsByType(String) Method

Definition

Namespace:

System.IO.Packaging

Assembly:

System.IO.Packaging.dll

Returns a collection of all the package-level relationships that match a given RelationshipType.

public:
 System::IO::Packaging::PackageRelationshipCollection ^ GetRelationshipsByType(System::String ^ relationshipType);

public System.IO.Packaging.PackageRelationshipCollection GetRelationshipsByType (string relationshipType);

member this.GetRelationshipsByType : string -> System.IO.Packaging.PackageRelationshipCollection

Public Function GetRelationshipsByType (relationshipType As String) As PackageRelationshipCollection

Parameters

relationshipType

String

The RelationshipType to match and return in the collection.

Returns

PackageRelationshipCollection

A collection of package-level relationships that match the specified relationshipType.

Exceptions

ArgumentNullException

relationshipType is null.

ArgumentException

relationshipType is an empty string.

ObjectDisposedException

The package is not open (Dispose(Boolean) or Close() has been called).

IOException

The package is write-only.

Examples

The following example shows how to retrieve the relationships that have been defined for the package.

// Open the Package.
// ('using' statement insures that 'package' is
//  closed and disposed when it goes out of scope.)
using (Package package =
    Package.Open(packagePath, FileMode.Open, FileAccess.Read))
{
    PackagePart documentPart = null;
    PackagePart resourcePart = null;

    // Get the Package Relationships and look for
    //   the Document part based on the RelationshipType
    Uri uriDocumentTarget = null;
    foreach (PackageRelationship relationship in
        package.GetRelationshipsByType(PackageRelationshipType))
    {
        // Resolve the Relationship Target Uri
        //   so the Document Part can be retrieved.
        uriDocumentTarget = PackUriHelper.ResolvePartUri(
            new Uri("/", UriKind.Relative), relationship.TargetUri);

        // Open the Document Part, write the contents to a file.
        documentPart = package.GetPart(uriDocumentTarget);
        ExtractPart(documentPart, targetDirectory);
    }

    // Get the Document part's Relationships,
    //   and look for required resources.
    Uri uriResourceTarget = null;
    foreach (PackageRelationship relationship in
        documentPart.GetRelationshipsByType(
                                ResourceRelationshipType))
    {
        // Resolve the Relationship Target Uri
        //   so the Resource Part can be retrieved.
        uriResourceTarget = PackUriHelper.ResolvePartUri(
            documentPart.Uri, relationship.TargetUri);

        // Open the Resource Part and write the contents to a file.
        resourcePart = package.GetPart(uriResourceTarget);
        ExtractPart(resourcePart, targetDirectory);
    }
}// end:using(Package package) - Close & dispose package.

' Open the Package.
' ('using' statement insures that 'package' is
'  closed and disposed when it goes out of scope.)
Using package As Package = Package.Open(packagePath, FileMode.Open, FileAccess.Read)
    Dim documentPart As PackagePart = Nothing
    Dim resourcePart As PackagePart = Nothing

    ' Get the Package Relationships and look for
    '   the Document part based on the RelationshipType
    Dim uriDocumentTarget As Uri = Nothing
    For Each relationship As PackageRelationship In package.GetRelationshipsByType(PackageRelationshipType)
        ' Resolve the Relationship Target Uri
        '   so the Document Part can be retrieved.
        uriDocumentTarget = PackUriHelper.ResolvePartUri(New Uri("/", UriKind.Relative), relationship.TargetUri)

        ' Open the Document Part, write the contents to a file.
        documentPart = package.GetPart(uriDocumentTarget)
        ExtractPart(documentPart, targetDirectory)
    Next relationship

    ' Get the Document part's Relationships,
    '   and look for required resources.
    Dim uriResourceTarget As Uri = Nothing
    For Each relationship As PackageRelationship In documentPart.GetRelationshipsByType(ResourceRelationshipType)
        ' Resolve the Relationship Target Uri
        '   so the Resource Part can be retrieved.
        uriResourceTarget = PackUriHelper.ResolvePartUri(documentPart.Uri, relationship.TargetUri)

        ' Open the Resource Part and write the contents to a file.
        resourcePart = package.GetPart(uriResourceTarget)
        ExtractPart(resourcePart, targetDirectory)
    Next relationship

End Using ' end:using(Package package) - Close & dispose package.

Remarks

GetRelationships will never return null; however the returned collection may contain zero elements if there are no package-level relationships that match the specified relationshipType.

The following table shows the package-level relationshipType URIs defined by the Open Packaging Conventions (OPC) specification.

Package-level Relationship	Relationship Type URI
Core Properties	http://schemas.openxmlformats.org/package/2006/relationships/metadata/core-properties
Digital Signature	http://schemas.openxmlformats.org/package/2006/relationships/digital-signature/signature
Digital Signature Certificate	http://schemas.openxmlformats.org/package/2006/relationships/digital-signature/certificate
Digital Signature Origin	http://schemas.openxmlformats.org/package/2006/relationships/digital-signature/origin
Thumbnail	http://schemas.openxmlformats.org/package/2006/relationships/metadata/thumbnail

For additional information, see the Open Packaging Conventions (OPC) specification available for download at https://www.ecma-international.org/publications-and-standards/standards/ecma-376/.

See also

• GetRelationship(String)
• GetRelationships()
• CreateRelationship(Uri, TargetMode, String)
• DeleteRelationship(String)