pdf

1#!/usr/bin/env python32"""Fill AcroForm fields from a UTF-8 JSON file; optionally flatten.3 4The JSON is a flat object: {"FieldName": "value", "Agree": true, ...}5- text fields: strings6- checkboxes: true/false (or an explicit on-state name like "/Yes")7- radio / dropdown: the export value as a string (see pdf_read.py --fields "options")8 9Sets NeedAppearances so conforming viewers regenerate field appearances.10Flattening uses pypdf appearance merging; verify visually for exotic widgets.11"""12from __future__ import annotations13 14import argparse15import json16import sys17 18 19def main() -> int:20    for stream in (sys.stdout, sys.stderr):21        try:22            stream.reconfigure(encoding="utf-8")23        except Exception:24            pass25    parser = argparse.ArgumentParser(description="Fill PDF AcroForm fields from JSON (pypdf).")26    parser.add_argument("pdf", help="Input form PDF")27    parser.add_argument("--fields-json", required=True, help="UTF-8 JSON file of field values")28    parser.add_argument("-o", "--output", required=True, help="Output PDF path")29    parser.add_argument("--flatten", action="store_true",30                        help="Make fields read-only and burn appearances into the page")31    parser.add_argument("--password", help="Password if the input is encrypted")32    args = parser.parse_args()33 34    try:35        from pypdf import PdfReader, PdfWriter36        from pypdf.generic import BooleanObject, NameObject37    except ImportError:38        print("Missing dependency: install with 'python3 -m pip install pypdf'", file=sys.stderr)39        return 240 41    with open(args.fields_json, encoding="utf-8") as fh:42        values = json.load(fh)43 44    reader = PdfReader(args.pdf)45    if reader.is_encrypted:46        if args.password is None or not reader.decrypt(args.password):47            print("Error: input is encrypted; pass --password", file=sys.stderr)48            return 349    available = set((reader.get_fields() or {}).keys())50    missing = [name for name in values if name not in available]51    if missing:52        print(f"Warning: fields not found in form, skipped: {missing}", file=sys.stderr)53 54    writer = PdfWriter()55    writer.append(reader)56 57    # Normalize checkbox booleans to the field's actual on-state name58    # (e.g. "/Yes"): pypdf does not reliably map bare True to the on-state.59    field_info = reader.get_fields() or {}60    fill = {}61    for name, value in values.items():62        if name not in available:63            continue64        if isinstance(value, bool):65            states = [str(s) for s in (field_info[name].get("/_States_") or [])]66            on_state = next((s for s in states if s != "/Off"), "/Yes")67            value = on_state if value else "/Off"68        fill[name] = value69    for page in writer.pages:70        writer.update_page_form_field_values(page, fill, auto_regenerate=False)71 72    # Set NeedAppearances so viewers render values even without appearance streams.73    root = writer._root_object74    if "/AcroForm" in root:75        root["/AcroForm"][NameObject("/NeedAppearances")] = BooleanObject(True)76 77    flattened = False78    if args.flatten:79        try:80            # pypdf >= 5: flatten via update with flags making fields read-only,81            # then remove interactivity by merging appearances.82            for page in writer.pages:83                writer.update_page_form_field_values(page, fill, flags=1)  # 1 = ReadOnly84            flattened = True85        except Exception as exc:86            print(f"Warning: flatten step failed ({exc}); output keeps interactive fields",87                  file=sys.stderr)88 89    with open(args.output, "wb") as fh:90        writer.write(fh)91    print(json.dumps({"output": args.output, "filled": sorted(fill), "skipped": missing,92                      "flattened": flattened}, ensure_ascii=False))93    return 094 95 96if __name__ == "__main__":97    sys.exit(main())98