fastify-xpdf
listFormFields
Enumerate all form fields in a PDF — name, type, and current value.
listFormFields
List all interactive form fields in a PDF using pdf-lib. Returns the field name, type, and current value for each field. Useful for inspecting a template before calling fillForm.
Signature
fastify.xPDF.listFormFields(pdfBuffer: Buffer): Promise<FormField[]>
interface FormField {
name: string
type: "text" | "checkbox" | "radio" | "dropdown" | "option" | "button" | "signature" | "unknown"
value: string | boolean | null
}
Params
| Name | Type | Required | Description |
|---|---|---|---|
pdfBuffer | Buffer | Yes | PDF buffer to inspect |
Returns
FormField[] — an array of all fields. Empty array if the PDF has no form fields.
Throws
| Error | When |
|---|---|
[xPDF] Invalid PDF buffer | pdfBuffer doesn't start with %PDF |
Examples
Inspect a template before filling
fastify.get("/templates/:name/fields", async (request, reply) => {
const template = await fetchTemplateBuffer(`${request.params.name}.pdf`);
const fields = await fastify.xPDF.listFormFields(template);
return {
fieldCount: fields.length,
fields: fields.map(({ name, type }) => ({ name, type })),
};
});
// Response:
// {
// "fieldCount": 5,
// "fields": [
// { "name": "firstName", "type": "text" },
// { "name": "lastName", "type": "text" },
// { "name": "agreeToTerms", "type": "checkbox" },
// { "name": "country", "type": "dropdown" },
// { "name": "signature", "type": "signature" }
// ]
// }
Validate that all required fields are present before filling
async function fillChecked(templateBuffer, values) {
const fields = await fastify.xPDF.listFormFields(templateBuffer);
const fieldNames = new Set(fields.map((f) => f.name));
const missing = Object.keys(values).filter((k) => !fieldNames.has(k));
if (missing.length > 0) {
throw new Error(`Unknown field names: ${missing.join(", ")}`);
}
return fastify.xPDF.fillForm(templateBuffer, values);
}
See Also
- fillForm — Fill field values returned by this method
AI Context
package: "@xenterprises/fastify-xpdf"
method: fastify.xPDF.listFormFields(pdfBuffer)
use-when: Enumerate all form fields in a PDF template with their names, types, and current values
params: pdfBuffer (Buffer)
returns: Array<{ name, type, value, required }>