96 lines
2.8 KiB
Python
96 lines
2.8 KiB
Python
"""
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Single-Letter-Preview: rendert ausschließlich die erste CSV-Zeile gegen das
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Template und gibt das resultierende PDF als Bytes zurück. Synchroner Pfad,
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keine Celery-Beteiligung – die View ruft das direkt im Request-Kontext auf.
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"""
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from __future__ import annotations
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import csv
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import io
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import logging
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import tempfile
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from dataclasses import dataclass
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from pathlib import Path
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from .docx_renderer import docx_to_pdf, extract_placeholders, render_docx
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logger = logging.getLogger(__name__)
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class PreviewError(Exception):
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"""Erwartete Fehler beim Preview – werden dem User angezeigt."""
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@dataclass
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class PreviewResult:
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pdf_bytes: bytes
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used_row: dict[str, str]
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placeholders: list[str]
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csv_columns: list[str]
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missing_columns: list[str]
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extra_columns: list[str]
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def _read_first_row(csv_file) -> tuple[list[str], dict[str, str]]:
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"""Liest CSV-Header + erste Datenzeile.
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Akzeptiert UploadedFile oder Path-ähnliches. UTF-8, Komma-getrennt.
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"""
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if hasattr(csv_file, "read"):
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raw = csv_file.read()
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if isinstance(raw, bytes):
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text = raw.decode("utf-8-sig")
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else:
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text = raw
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else:
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text = Path(csv_file).read_text(encoding="utf-8-sig")
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reader = csv.DictReader(io.StringIO(text))
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if not reader.fieldnames:
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raise PreviewError("CSV-Datei enthält keine Header-Zeile.")
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try:
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row = next(reader)
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except StopIteration as exc:
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raise PreviewError(
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"CSV-Datei enthält außer dem Header keine Datenzeile."
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) from exc
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return list(reader.fieldnames), row
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def build_preview(template_path: Path, csv_file) -> PreviewResult:
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"""Rendert die erste CSV-Zeile gegen das Template und liefert ein PDF.
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Validiert vorab Header gegen die Template-Platzhalter und meldet
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fehlende / überflüssige Spalten.
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"""
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placeholders = extract_placeholders(template_path)
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columns, first_row = _read_first_row(csv_file)
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placeholder_set = set(placeholders)
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column_set = set(columns)
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missing = sorted(placeholder_set - column_set)
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extra = sorted(column_set - placeholder_set)
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if missing:
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raise PreviewError(
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"Folgende Platzhalter sind im Template enthalten, "
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"fehlen aber als Spalte in der CSV: "
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+ ", ".join(missing)
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)
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with tempfile.TemporaryDirectory(prefix="serienbrief-preview-") as tmp:
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tmpdir = Path(tmp)
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docx_out = tmpdir / "preview.docx"
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render_docx(template_path, first_row, docx_out)
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pdf_path = docx_to_pdf(docx_out, tmpdir)
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pdf_bytes = pdf_path.read_bytes()
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return PreviewResult(
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pdf_bytes=pdf_bytes,
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used_row=first_row,
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placeholders=placeholders,
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csv_columns=columns,
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missing_columns=missing,
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extra_columns=extra,
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)
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