## Overview

The **Add files to Writer Cloud** block uploads files to the Writer cloud so you can use them in your workflows. It accepts a list of file objects as inputs.

## File inputs

The **Add files to Writer Cloud** block accepts a list of file objects as inputs. Each file object must have the following fields:

| Field | Type | Description |
| --- | --- | --- |
| `name` | string | The name of the file. |
| `data` | bytes | The content of the file as bytes. |
| `type` | string | The [MIME type](https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/MIME_types/Common_types) of the file. |

### Adding files from the file input block

If you upload a file with the **File input** interface block, the list of file objects is automatically created for you, so all you have to do is pass the list to the **Add files to Writer Cloud** block. You can retrieve the file objects list from the **File input** interface block in two ways:

- Connect a UI Trigger to the **File input** block’s `wf-file-change` event. Then, use the `@{payload}` environment variable to access the file objects. The trigger will fire when a user adds or removes files from the file input block.
- Under **Binding** in the **File input** interface block, define a state variable that contains the list of file objects. Then reference that variable in the **Add files to Writer Cloud** block.

## Output

Once the files are uploaded to the Writer cloud, the **Add files to Writer Cloud** block returns a list containing the uploaded file IDs and other information about the files. Each file object has the following fields:

| Field | Type | Description |
| --- | --- | --- |
| `id` | string | The ID of the file. |
| `name` | string | The name of the file. |
| `status` | string | The status of the file. Can be `in_progress`, `completed`, or `failed`. |
| `created_at` | string | The date and time the file was created. |
| `graph_ids` | array | The IDs of any Knowledge Graphs that the file is associated with. |

```
[\
    {\
        "id": "701118ae",\
        "name": "research_paper.pdf",\
        "status": "in_progress",\
        "created_at": "2025-06-17T16:18:42.672407+00:00",\
        "graph_ids": []\
    }\
]
```

### File processing status

If the uploaded file’s status is `in_progress`, the file is being processed and is not ready to be used in a workflow. Some files are processed quickly, such as PDFs and images, and are ready to be used in a workflow within seconds. There are a few ways you can handle files that are still being processed:

- Split the blueprint into two parts: one that uploads the files when a user adds them to the file input block, and another that uses the files when a user clicks a button in the UI. This way, you can use the files in the workflow as soon as they’re uploaded, and wait for the user to click a button to use the files in the second part of the blueprint.
- Add a Python block that introduces a few seconds of delay before the workflow continues.
- Add a [**Tool calling** block](https://dev.writer.com/agent-builder/tool-calling) that can check the status of the file [using the Writer API](https://dev.writer.com/api-reference/file-api/get-file) and wait for the file to be processed before continuing.

## Example: Upload files to Writer Cloud from the file input block

This example shows how to upload files to Writer Cloud that are stored in a state variable. The interface contains a file input block that’s bound to the state variable `files`. After the UI Trigger fires, the **Add files to Writer Cloud** block uploads the files to Writer Cloud by accessing the `@{files}` state variable.

```
[\
    {\
        "name": "research_paper.pdf",\
        "data": "...",\
        "type": "application/pdf"\
    }\
]
```

## Example: Create and upload files from Python processing

This example shows how to manually create file objects in a **Python code** block and then upload them to Writer Cloud. In this scenario, a Python block generates a CSV report from data processing and creates the file object programmatically.

```
import csv
import io

# Sample data processing
data = [\
    ["Name", "Score", "Category"],\
    ["Product A", 85, "Electronics"],\
    ["Product B", 92, "Home & Garden"],\
    ["Product C", 78, "Electronics"]\
]

# Create CSV content
csv_buffer = io.StringIO()
writer = csv.writer(csv_buffer)
writer.writerows(data)
csv_content = csv_buffer.getvalue()

# Convert to bytes
csv_bytes = csv_content.encode('utf-8')

# Create file object
file_object = {
    "name": "product_analysis.csv",
    "data": csv_bytes,
    "type": "text/csv"
}

# Return the file object as a list (required by Add files to Writer Cloud block)
set_output([file_object])
```

## Fields

| Name | Type | Control | Default | Description | Options | Validation |
| --- | --- | --- | --- | --- | --- | --- |
| Files | Object | - | `[]` | A list of files to be uploaded to the Writer platform. You can use files uploaded via the File input component or specify dictionaries with data, type and name. | - | - |

## End states

Below are the possible end states of the block call.

| Name | Field | Type | Description |
| --- | --- | --- | --- |
| Success | - | success | File successfully uploaded. |
| Error | - | error | There was an error uploading the files. |

Access the output of a **Add files to Writer Cloud** block using the `@{result}` variable in the block that follows it in a blueprint.