File attachments

With Episerver Find, you can index external attachments in different formats such as Word and PDF. This topic describes supported file formats and explains how to work with search relevancy for attached files.

How it works

To index attachments using the .NET API, create an instance of a class that has a property of type Attachment (found in the EPiServer.Find namespace). The Attachment class constructor has a single parameter of type Func<FileStream>. Another class, FileAttachment (also in the EPiServer.Find namespace) requires a file path as a constructor parameter.

Examples

You create a class named Document.

C#

public class Document
{
    public string Name { get; set; }
    public Attachment Attachment { get; set; }
}

You can index an instance of the Document class to index a Word document along with some metadata (Name in this example).

C#

var path = "TestData/Memoirs.docx";

var document = new Document()
  {
    Name = "My memoirs",
    Attachment = new FileAttachment(path);
  }

client.Index(document);

You can search the indexed Word document. For example, if it contains "Banana," the result variable below would contain a hit.

C#

var result = client.Search<Document>()
                   .For("Banana").GetResult();

Note: A REST API issue causes an exception the first time an instance of a type with an Attachment property (document in this example) is indexed. This only happens the first time--after that, everything works as expected.

Improving search relevancy of attachments

By default, search relevancy for text inside an attachment is imperfect. This is because attachments are indexed in the default language, which might not match the document's content. (CMS content, in contrast, is indexed using all enabled languages to improve search relevancy.)

Also, when browsing Find's explore view of an attachment, the attachment text is not readable, because it is indexed using the base64 representation of itself.

To improve the search relevancy of text attachments, use the IAttachmentHelper interface, which enables developers to implement their own parsing of attachments. Out of the box, Episerver provides an implementation of IAttachmentHelper that uses Microsoft IFilter functionality. For this to work, the correct IFilters need to be installed on the client.

Implementing the IAttachmentHelper

Install the EPiServer.Find.Cms.AttachmentFilter Nuget package.
Determine which attachment file types you want to support (for example, PDF and Microsoft Word). Each file type has a corresponding filter. The list of file types and filters is below.
Download and install the selected filters.
Restart.
Add some supported file attachments to your site.
Log into your website and browse to Find > Overview > Explore.
Find the attachments and verify that their content is stored as readable text under SearchAttachmentText$$String.

Supported file formats

The file types below can be parsed using Ifilters and Episerver Find.

adw, ai, doc, docm, docx, dwg, eps, gif, html, htm, jpeg, jpg, mm, msg, odt, ods, odp, odi, one, otf, otp, pdf, png, ppt, pptm, pptx, ps, rar, sda, sdg, sdm, sfs, sgf, smf, std, sti, stw, svg, sxd, sxi, txt, vdx, vsd, vdx, vor, vss, vst, vsx, vtx, wma, wmv, xls, xlsb, xlsm, xlsx, xml, zip.

For many file types, more than one filter is available. See below for common file types and filters, and additional filter sources.

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