# PDF indexes and multisearchers

If you want to index PDF files and search for them you will need to use the [UmbracoExamine.Pdf extension package](https://github.com/umbraco/UmbracoExamine.PDF).

## Installation

Install with NuGet:`dotnet add package Umbraco.ExaminePDF`

This will create a new Examine index called "PDFIndex", which will appear in "Examine Management" dashboard under the "Settings" section. Using this index you can start searching the contents of any PDF files uploaded to the media section.

![image](https://user-images.githubusercontent.com/7405322/189886089-d23b45c7-814b-4101-b143-31c5cd9fa655.png)

## Multi-index searchers

A multi-index searcher is a searcher that can search multiple indexes. This can be helpful when you for example want to search both the external and internal indexes.\
You can register a multi-index searcher with the ExamineManager on startup like:

```csharp
using Examine;
using Umbraco.Cms.Core;
using Umbraco.Cms.Core.Composing;
using Umbraco.Cms.Core.DependencyInjection;
using UmbracoExamine.PDF;

namespace MySite.MyCustomIndex;

[ComposeAfter(typeof(ExaminePdfComposer))]
public class ExamineComposer : IComposer
{
    public void Compose(IUmbracoBuilder builder)
    {
        builder.Services.AddExamineLuceneMultiSearcher("MultiSearcher", new[] {Constants.UmbracoIndexes.ExternalIndexName, PdfIndexConstants.PdfIndexName});
    }
}
```

With this approach, the multi-index searcher will show up in the "Examine Management" dashboard.

![image](https://user-images.githubusercontent.com/7405322/189887744-af2d8e69-4807-4407-868d-b43e9fa9518d.png)

The multi-index searcher can be resolved in code from the ExamineManager like this:

```csharp
if (_examineManager.TryGetSearcher("MultiSearcher", out var searcher))
{
    //TODO: use the `searcher` to search
}
```

{% hint style="warning" %}
The implementation of IPdfTextExtractor is PdfSharpTextExtractor in this library, which uses PDFSharp to extract the bytes to convert to text. That implementation doesn't deal well with Unicode text which means when some PDF files are read, the result will be 'junk' strings.

It is certainly possible to replace the IPdfTextExtractor using your own composer like

`composition.RegisterUnique<IPdfTextExtractor, MyCustomSharpTextExtractor>();`

The iTextSharp library deals with Unicode in a better way but is a paid for license. If you wish to use iTextSharp or another PDF library you can swap out the IPdfTextExtractor with your own implementation.
{% endhint %}


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