Merge multiple files and dynamically add a 'Table of Contents' to the PDF

In this post, we’ll explore one of the new actions introduced in the first Encodian Flowr release 2025!

The ‘PDF – Insert Table of Contents‘ action can be found within the Encodian Flowr PDF connector. We will demonstrate how to add a dynamic table of contents to a PDF document by merging individual PDFs.

This solution uses this new Flowr action and the PDF – Merge Files action.

To deliver this example solution, I’ve created a PowerApp, which is aligned to the scenario of creating a single legal case PDF document ‘bundled’ from multiple PDF files. The high-level steps are:

1. PDF documents are uploaded to a Power App
2. The individual documents are saved to a folder in SharePoint
3. The documents are merged into one PDF
4. A table of contents is added to the merged PDF
5. The final PDF document is saved to the same SharePoint folder
6. The link to the final PDF document is sent back to the Power App

Blog Contents

• Power App
• Power Automate Flow
• Results

Bundle Files with a Power App

I have created a simple, one-screen Power App where users can upload documents they want to merge. The documents can be in any format because the PDF—Merge Files action can merge non-PDF documents. Non-PDF documents are silently converted to PDF as part of the merge process.

The user must also provide a client name; if no name is provided, the submit button will be disabled.

When the ‘Create Case Document‘ button is pressed, it triggers a Power Automate flow, which executes the generation of the single PDF document. Upon completion, the flow returns a link to the final PDF document to the app, allowing the user to open it immediately.

We need to format the added attachments so that we can send them to Power Automate. We can achieve this using collections and a hidden gallery.

The OnAddFile and the OnRemoveFile properties of the attachment control both use this formula:

ClearCollect(
    colDocs,
    uploadFiles.Attachments
);

ThisItem.Value

The OnSelect property of the ‘Create Case Bundle‘ button uses these formulas:

Clear(colDocGal);

ForAll(
    dataStreamGallery.AllItems,
    Collect(
        colDocGal,
        {
            Title: Title.Text,
            dataStream: dataStreamImg.Image
        }
    )
);

Set(varDocLink, PDFTableofContents.Run(clientNameTxtInput.Text, JSON(colDocGal, JSONFormat.IncludeBinaryData)).doclink)

The ‘Clear’ formula ensures that ‘colDocGal’ variable is empty before we start populating it.

Attachment Control

On Add File / On Remove File:

ClearCollect(
    colDocs,
    uploadFiles.Attachments
);

Create Case Document Button

Display Mode:

If(
    Or(
        IsEmpty(uploadFiles.Attachments),
        IsBlank(clientNameTxtInput.Text)
    ),
    DisplayMode.Disabled,
    DisplayMode.Edit
)

On Select

Clear(colDocGal);

ForAll(
    dataStreamGallery.AllItems,
    Collect(
        colDocGal,
        {
            Title: Title.Text,
            dataStream: dataStreamImg.Image
        }
    )
);

Set(varDocLink, PDFTableofContents.Run(clientNameTxtInput.Text, JSON(colDocGal, JSONFormat.IncludeBinaryData)).doclink)

Results Container

The visibility of this container is controlled by the variable ‘varDocLink’ by the following formula:

!IsBlank(varDocLink)

Launch(varDocLink)

!IsBlank(varDocLink)

Reset(uploadFiles);
Reset(clientNameTxtInput);
Set(varDocLink, Blank())

Power Automate Flow

Two approaches to building this flow can be used depending on the document to which you are adding the table of contents.

If (per this example) you are merging documents before adding the ‘Table of Contents, ‘ you can pass the merged file from the ‘PDF – Merge Documents’ action directly to the ‘PDF – Insert Table of Contents’ action. This works because the ‘PDF – Merge Documents’ action automatically creates a bookmark for each merged file, which the ‘PDF – Insert Table of Contents’ action can then use to create the ‘Table of Contents’ automatically.

If the PDF document you are sending to the ‘PDF – Insert Table of Contents’ action doesn’t contain bookmarks, you can build and provide a JSON dataset that represents the ‘Table of Contents’ entries that are processed and used to create the ‘Table of Contents’ within the PDF document provided.

The Power Automate flow is triggered by the Power App, so the ‘Power Apps (V2)’ trigger is used. There are two text input values:

• clientName – the given name of the client
• documents – JSON of colDocsGal

I am initialising one array variable called ‘docArray’. This variable will contain the file content of the documents to merge.

The created document bundle and the individual documents will be saved in SharePoint within a dedicated folder created using the ‘Create new folder’ action. I am using the replace expression for the folder path to replace any spaces with an underscore, this helps prevent this action from failing. The expression used is:

replace(triggerBody()['text'], ' ', '_')

Before we can use the JSON data provided by the Power App, we need to parse it using the ‘Parse JSON‘ action. The content will be the documents input variable that we defined in the trigger action. If you have used the same column names for the collection ‘colDocsGal’ in the Power App, then the Schema will look like this:

{
    "type": "array",
    "properties": {
        "Title": {
            "type": "string"
        },
        "dataStream": { 
            "type": "string"          
        }
    }
}

Now, we can loop through each document by iterating over the ‘Body’ output of the ‘Parse JSON‘ action.

The first step is composing the file content of the document using the following expression:

dataUriToBinary(items('Apply_to_each_document')?['dataStream'])

Next, I append the ‘fileName’ and the ‘fileContent’ to the docArray. We will use this array when merging the documents.

Once we have finished looping through each document, we will have a complete ‘docArray’. We will use these in the next two actions.

Firstly, we need to merge all the documents stored in the ‘docArray’ into a single PDF document. We will do this using Flowr’s PDF – Merge Files action. This action will automatically convert all the documents provided to PDF, so you don’t need to do a separate conversion first.

After merging the documents, we can insert the ‘Table of Contents’ using Flowr’s PDF – Insert Table of Contents action. This action offers various styling options, but I have left these inputs as the defaults.

Because the PDF – Merge Files action already added bookmarks to my document, all I need to provide is the ‘File Content’, Title, and Destination Page. The action will use the contained PDF bookmarks to build the ‘Table of Contents’.

If your document doesn’t have bookmarks, you will need to build up a JSON dataset like this:

{
"Title": "Name of section",
"Destination": "Page number section starts",
"Level": "1",
"Children": []
}

The Title is the section’s name as it will appear in the table of contents.

The Destination is the page number where the section starts.

The Level determines the bookmark’s level. If you are using level 2 or more bookmarks, the data for these bookmarks will be put in the Children array.

You would need to build up this JSON for each section of your document.

The last thing to do is create the final document in the SharePoint folder. Once the file is created, we need to use the SharePoint ‘Get file properties’ action to return the document link to Power Apps.

Results

I have uploaded to the Power App three different document types: a PDF, an image, and a Word document.

This is the resulting folder and files created in SharePoint:

This is the bundled PDF document in a two-page view. We can see that each file has been converted into PDF and merged correctly.

This is the table of contents that has been added to the merged documents. We can see that each document includes the correct page number.