Working with feature attachments

In this topic

• Attachment tables
• Querying attachments
• Adding attachments
• Deleting attachments
• Updating attachments

Attachment tables

• HasAttachments—Read-only Boolean property that indicates whether an attachment table exists for a feature class.
• AttachmentManager—Read-only property instantiates and returns an attachment manager for the feature class and its attachment table. An attachment manager is used to query, add, delete, and update attachments through the IAttachmentManager interface.

• AddAttachments—Creates an attachment table for the feature class. Feature classes cannot have multiple attachment tables.
• DeleteAttachments—Deletes the attachment table.

Querying attachments

• AttachmentID—Attachment's ObjectID.
• ContentType—Describes the type of data contained in the attachment.
• Data—Attachment's data.
• Name—Attachment's file name.
• ParentID—ObjectID of the associated feature.
• Size—Size of the attachment's data in bytes.

// Get the class's attachment manager.
ITableAttachments tableAttachments=(ITableAttachments)featureClass;
IAttachmentManager attachmentManager=tableAttachments.AttachmentManager;

// Create an array and add the feature's ObjectID to it.
ILongArray parentIdArray=new LongArrayClass();
parentIdArray.Add(1);

// Retrieve the attachments, writing their Attachment IDs and names to the console.
IEnumAttachment enumAttachment=attachmentManager.GetAttachmentsByParentIDs
    (parentIdArray, true);
enumAttachment.Reset();
IAttachment attachment=null;
while ((attachment=enumAttachment.Next()) != null)
{
    Console.WriteLine("{0}: {1}", attachment.AttachmentID, attachment.Name);
}

' Get the class's attachment manager.
Dim tableAttachments As ITableAttachments=CType(featureClass, ITableAttachments)
Dim attachmentManager As IAttachmentManager=tableAttachments.AttachmentManager

' Create an array and add the feature's ObjectID to it.
Dim parentIdArray As ILongArray=New LongArrayClass()
parentIdArray.Add(1)

' Retrieve the attachments, writing their Attachment IDs and names to the console.
Dim enumAttachment As IEnumAttachment=attachmentManager.GetAttachmentsByParentIDs(parentIdArray, True)
enumAttachment.Reset()
Dim attachment As IAttachment=enumAttachment.Next()
While Not attachment Is Nothing
    Console.WriteLine("{0}: {1}", attachment.AttachmentID, attachment.Name)
    attachment=enumAttachment.Next()
End While

// Create an array and add the attachment's Attachment ID to it.
ILongArray attachmentIdArray=new LongArrayClass();
attachmentIdArray.Add(attachmentID);

// Retrieve the attachment, saving its data to the current directory.
IEnumAttachment enumAttachment=attachmentManager.GetAttachmentsByAttachmentIDs
    (attachmentIdArray, false);
enumAttachment.Reset();
IAttachment attachment=enumAttachment.Next();
if (attachment != null)
{
    IMemoryBlobStream memoryBlobStream=attachment.Data;
    memoryBlobStream.SaveToFile(attachment.Name);
}

' Create an array and add the attachment's Attachment ID to it.
Dim attachmentIdArray As ILongArray=New LongArrayClass()
attachmentIdArray.Add(attachmentID)

' Retrieve the attachment, saving its data to the current directory.
Dim enumAttachment As IEnumAttachment=attachmentManager.GetAttachmentsByAttachmentIDs(attachmentIdArray, False)
enumAttachment.Reset()
Dim attachment As IAttachment=enumAttachment.Next()
If Not attachment Is Nothing Then
    Dim memoryBlobStream As IMemoryBlobStream=attachment.Data
    memoryBlobStream.SaveToFile(attachment.Name)
End If

Adding attachments

1. Load a file into a memory blob stream.
2. Instantiate an attachment and set its properties.
3. Use the attachment manager to apply the attachment to the feature.

// Open a file as a memory blob stream.
IMemoryBlobStream memoryBlobStream=new MemoryBlobStreamClass();
memoryBlobStream.LoadFromFile("Image1.png");

// Create an attachment.
IAttachment attachment=new AttachmentClass
{
    ContentType="image/png", Data=memoryBlobStream, Name="Image1.png"
};

// Assign the attachment to the feature with ObjectID (OID)=1.
attachmentManager.AddAttachment(1, attachment);

' Open a file as a memory blob stream.
Dim memoryBlobStream As IMemoryBlobStream=New MemoryBlobStreamClass()
memoryBlobStream.LoadFromFile("Image1.png")

' Create an attachment.
Dim attachment As IAttachment=New AttachmentClass With _
                                { _
                                .ContentType="image/png", _
                                .Data=memoryBlobStream, _
                                .Name="Image1.png" _
                                }

' Assign the attachment to the feature with ObjectID (OID)=1.
attachmentManager.AddAttachment(1, attachment)

Deleting attachments

• DeleteAttachment—Deletes a single attachment using its Attachment ID.
• DeleteAttachmentsForParent—Deletes all attachments for a single feature (takes the feature's ObjectID as a parameter).

Updating attachments

// Rename a previously retrieved attachment and persist the change.
attachment.Name="LosAngeles.png";
attachmentManager.UpdateAttachment(attachment);

' Rename a previously retrieved attachment and persist the change.
attachment.Name="LosAngeles.png"
attachmentManager.UpdateAttachment(attachment)

• ESRI.ArcGIS.Geodatabase
• ESRI.ArcGIS.System (ESRI.ArcGIS.esriSystem)