> ## Documentation Index
> Fetch the complete documentation index at: https://learn.workflow.dog/llms.txt
> Use this file to discover all available pages before exploring further.
# Files and Structured Data
> Move between files, text, objects, JSON, YAML, and data URLs without losing the intended format.
WorkflowDog treats files, strings, and structured values as different data
types. Keep them distinct until a system boundary requires a conversion.
## Know what you have
| Value | Contains | Typical use |
| ------------------ | ----------------------------------------------------- | ---------------------------------------------------- |
| **File** | A name, MIME type, encoding, and base64-encoded bytes | Uploads, attachments, downloads, images, PDFs |
| **String** | Text | Prompts, messages, CSV text, JSON text, HTML |
| **Object or List** | Structured workflow data | API payloads, records, branching, property selection |
| **Data URL** | A string containing a MIME type and base64 data | Embedded browser or API content |
Changing a filename does not convert bytes, and serializing an object does not
create a File. Use an explicit conversion action so the boundary is visible on
the canvas.
## Create and download files
Use [Create Text File](/reference/actions/files/create-text-file) when the
content already exists as a String. Supply the complete filename, including an
extension. To deliver structured data as a file, convert the value to JSON,
create `report.json` from that text, then upload, attach, or return the
resulting File.
The filename extension is used to infer the MIME type when recognized.
Use [Download File from URL](/reference/actions/files/download-from-url) to
retrieve a public resource. You can provide a filename or let the action derive
one from the URL path. It uses the response's content type when available and
fails for non-success responses.
Download File from URL blocks local, internal, and private network addresses.
It is for public resources, not for reaching services inside a private
network.
## Rename without converting
[Rename File](/reference/actions/files/rename) returns a copy with a new name
while preserving its bytes and MIME type.
Renaming `invoice.png` to `invoice.jpg` still leaves PNG image data inside the
file and preserves the original MIME type. Use a format-specific conversion
action when the content itself must change.
## Convert files to and from data URLs
[Convert File to Data URL](/reference/actions/files/file-to-data-url) creates a
String in this form:
```text theme={null}
data:image/png;base64,iVBORw0KGgo...
```
This is useful when HTML or an API requires embedded content. Base64 increases
the representation's size, so prefer a File when the receiving action accepts
one.
[Convert Data URL to File](/reference/actions/files/data-url-to-file) performs
the reverse operation. Its input must use the exact
`data:MIME_TYPE;base64,DATA` form. The output is named
`converted.EXTENSION`, with the extension derived from the MIME type.
A normal `https://` URL is not a data URL. Download it with **Download File
from URL** instead.
## Parse JSON text
[Parse JSON](/reference/actions/core/json-parse) converts a valid JSON String
into its native value: an Object, List, String, Number, Boolean, or `null`.
```json theme={null}
{
"customer": {
"id": "cus_123",
"active": true
},
"tags": ["new", "priority"]
}
```
After parsing, select the properties downstream actions need. See
[Connect Data](/building/connect-data#select-part-of-an-object) for property
outputs.
Malformed JSON causes the action to fail. JSON requires double-quoted strings
and does not allow comments or trailing commas.
## Serialize values as JSON or YAML
[Convert to JSON](/reference/actions/core/json-stringify) serializes a
workflow value as JSON text. Enable pretty formatting for human-readable
output; compact output is usually better for API requests or storage.
[Convert to YAML](/reference/actions/core/yaml-stringify) emits YAML using
two-space indentation. Its **Use references?** option represents repeated
objects with YAML anchors and aliases. Leave references off when every section
should be standalone and easy to copy.
Serialization is useful at an external boundary:
For example, build an Object, convert it to JSON, then create `payload.json`
from the serialized text.
Do not serialize only to parse the value again in the next node. Connect the
original Object or List directly and preserve its types.
## Validate structured data
[Validate JSON Schema](/reference/actions/utilities/validate-json-schema)
checks any value against a JSON Schema and returns:
* **Is Valid**, a Boolean;
* **Errors**, a list containing every validation error found; and
* the original validated value or top-level property outputs, depending on the
schema.
For an object schema, the node exposes properties declared under the schema's
top-level `properties`. Connect **Is Valid** to
[Route Value](/reference/actions/control/demux) or a **Conditional** meta
control before using those values. One safe pattern is:
1. Parse the JSON text.
2. Validate the parsed value against the schema.
3. Connect both the validated object and **Is Valid** to **Route Value**.
4. Continue processing from **If True**.
5. Use **If False** to record the validator's **Errors**.
Validation does not coerce types. The String `"18"` does not satisfy an
`integer` schema. It also does not strip extra properties, and property outputs
remain the supplied values even when validation fails.
An ordinary schema mismatch returns **Is Valid: false**. Malformed JSON or an
invalid schema fails the action itself. Handle those as separate failure
cases.
## Choose the right conversion
Use **Convert to JSON**. If the API action accepts a structured body
directly, connect the Object instead.
Use **Parse JSON**, then select properties from the resulting value.
Use **Create Text File** and give it the correct filename extension.
Use **Download File from URL**.
Use **Convert File to Data URL**.