Mindestbestand in jeder angelegten Einheit erfassbar (und gemerkt)

- Produktformular: Auswahl aller verwalteten Einheiten passender Art (plus
  Packungen), inkl. Umrechnung beim Wechsel.
- Die gewaehlte Erfassungseinheit wird gespeichert (products.min_stock_unit_id /
  min_stock_in_packages) und exakt so wieder angezeigt - vorher wurde sie aus der
  Produkteinheit abgeleitet.
- ProductOut liefert min_stock_display + min_stock_unit_label; Produkttabelle
  zeigt den Mindestbestand damit in der erfassten Einheit mit Einheit dahinter.
- Migration: ADD COLUMN IF NOT EXISTS fuer die zwei neuen Spalten.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/app/crud.py

@@ -30,6 +30,18 @@ def product_to_out(db: Session, product: Product) -> ProductOut:
     name, factor = display_unit_info(product)
     out.unit_name = name
     out.unit_factor = factor
+
+    # Mindestbestand in der Einheit anzeigen, in der er erfasst wurde.
+    if product.min_stock is not None:
+        if product.min_stock_in_packages and product.package_size:
+            out.min_stock_display = product.min_stock / product.package_size
+            out.min_stock_unit_label = "Pkg"
+        elif product.min_stock_unit is not None:
+            out.min_stock_display = product.min_stock / product.min_stock_unit.factor
+            out.min_stock_unit_label = product.min_stock_unit.name
+        else:
+            out.min_stock_display = product.min_stock / factor
+            out.min_stock_unit_label = name
     return out
 
 

backend/app/main.py

@@ -37,6 +37,10 @@ def _ensure_schema() -> None:
         "REFERENCES units(id) ON DELETE SET NULL",
         "ALTER TABLE groups ADD COLUMN IF NOT EXISTS min_stock_unit_id INTEGER "
         "REFERENCES units(id) ON DELETE SET NULL",
+        "ALTER TABLE products ADD COLUMN IF NOT EXISTS min_stock_unit_id INTEGER "
+        "REFERENCES units(id) ON DELETE SET NULL",
+        "ALTER TABLE products ADD COLUMN IF NOT EXISTS min_stock_in_packages BOOLEAN "
+        "NOT NULL DEFAULT FALSE",
     ]
     with engine.begin() as conn:
         for stmt in stmts:

backend/app/models.py

@@ -124,13 +124,21 @@ class Product(Base):
         ForeignKey("groups.id", ondelete="SET NULL"), nullable=True
     )
     min_stock: Mapped[float | None] = mapped_column(Float, nullable=True)  # in base units
+    # In welcher Einheit der Mindestbestand erfasst wurde (nur für die Anzeige).
+    min_stock_unit_id: Mapped[int | None] = mapped_column(
+        ForeignKey("units.id", ondelete="SET NULL"), nullable=True
+    )
+    min_stock_in_packages: Mapped[bool] = mapped_column(
+        Boolean, nullable=False, default=False
+    )
 
     source: Mapped[str] = mapped_column(String(16), nullable=False, default="manual")
     off_raw: Mapped[str | None] = mapped_column(Text, nullable=True)  # JSON blob from OFF
     created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=_now)
 
     group: Mapped[Group | None] = relationship(back_populates="products")
-    display_unit: Mapped[Unit | None] = relationship()
+    display_unit: Mapped[Unit | None] = relationship(foreign_keys=[display_unit_id])
+    min_stock_unit: Mapped[Unit | None] = relationship(foreign_keys=[min_stock_unit_id])
     lots: Mapped[list[Lot]] = relationship(
         back_populates="product", cascade="all, delete-orphan"
     )

backend/app/routers/products.py

@@ -84,6 +84,8 @@ def create_product(
         package_size=payload.package_size,
         group_id=payload.group_id,
         min_stock=payload.min_stock,
+        min_stock_unit_id=payload.min_stock_unit_id,
+        min_stock_in_packages=bool(payload.min_stock_in_packages),
         source="manual",
     )
     db.add(product)
@@ -125,6 +127,8 @@ def update_product(
                 product.base_unit, product.display_unit_id = resolve_product_unit(db, unit_id)
             except ConversionError as exc:
                 raise HTTPException(status.HTTP_400_BAD_REQUEST, str(exc)) from exc
+    if data.get("min_stock_in_packages") is None:
+        data.pop("min_stock_in_packages", None)  # Spalte ist NOT NULL
     for field, value in data.items():
         setattr(product, field, value)
     db.commit()

backend/app/schemas.py

@@ -100,7 +100,10 @@ class ProductBase(BaseModel):
     unit_id: int | None = None
     package_size: float | None = Field(default=None, gt=0)
     group_id: int | None = None
-    min_stock: float | None = Field(default=None, ge=0)
+    min_stock: float | None = Field(default=None, ge=0)  # immer in Basiseinheiten
+    # Nur für die Anzeige: in welcher Einheit der Mindestbestand erfasst wurde.
+    min_stock_unit_id: int | None = None
+    min_stock_in_packages: bool = False
 
 
 class ProductCreate(ProductBase):
@@ -117,6 +120,8 @@ class ProductUpdate(BaseModel):
     package_size: float | None = Field(default=None, gt=0)
     group_id: int | None = None
     min_stock: float | None = Field(default=None, ge=0)
+    min_stock_unit_id: int | None = None
+    min_stock_in_packages: bool | None = None
 
 
 class ProductOut(BaseModel):
@@ -131,6 +136,8 @@ class ProductOut(BaseModel):
     package_size: float | None
     group_id: int | None
     min_stock: float | None
+    min_stock_unit_id: int | None = None
+    min_stock_in_packages: bool = False
     source: str
     created_at: datetime
     # angereichert:
@@ -139,6 +146,9 @@ class ProductOut(BaseModel):
     kind: str = ""
     unit_name: str = ""
     unit_factor: float = 1.0
+    # Mindestbestand in der erfassten Einheit (für die Anzeige):
+    min_stock_display: float | None = None
+    min_stock_unit_label: str = ""
 
 
 class LookupResult(BaseModel):

web/src/pages/ProductForm.jsx

@@ -29,8 +29,8 @@ export default function ProductForm() {
   const [error, setError] = useState(null);
   const [info, setInfo] = useState(null);
   const [busy, setBusy] = useState(false);
-  // Einheit für die Mindestbestand-Eingabe: "unit" (gewählte Einheit) oder "package".
+  // Einheit für die Mindestbestand-Eingabe: "package" oder die ID einer Einheit.
-  const [minUnit, setMinUnit] = useState("unit");
+  const [minUnit, setMinUnit] = useState("");
   const [warnDays, setWarnDays] = useState(7);
 
   const selectedUnit = units.find((u) => String(u.id) === String(form.unit_id)) || null;
@@ -48,19 +48,20 @@ export default function ProductForm() {
   }
 
   // Faktor, mit dem der angezeigte Mindestbestand in Basiseinheiten umgerechnet wird.
-  function minFactor(mode, pkgSize, uFactor) {
+  // sel ist "package" oder die ID einer verwalteten Einheit.
-    if (mode === "package") return Number(pkgSize) > 0 ? Number(pkgSize) : 1;
+  function minFactor(sel, pkgSize, unitList) {
-    return uFactor || 1;
+    if (sel === "package") return Number(pkgSize) > 0 ? Number(pkgSize) : 1;
+    const u = unitList.find((x) => String(x.id) === String(sel));
+    return u ? u.factor : 1;
   }
 
-  function changeMinUnit(newUnit) {
+  function changeMinUnit(newSel) {
-    if (form.min_stock !== "" && newUnit !== minUnit) {
+    if (form.min_stock !== "" && newSel !== minUnit) {
-      const oldF = minFactor(minUnit, form.package_size, unitFactor);
+      const oldF = minFactor(minUnit, form.package_size, units);
-      const newF = minFactor(newUnit, form.package_size, unitFactor);
+      const newF = minFactor(newSel, form.package_size, units);
-      const base = Number(form.min_stock) * oldF;
+      set("min_stock", String((Number(form.min_stock) * oldF) / newF));
-      set("min_stock", String(base / newF));
     }
-    setMinUnit(newUnit);
+    setMinUnit(newSel);
   }
 
   function applySuggestion(s, groupsList, unitList) {
@@ -120,9 +121,13 @@ export default function ProductForm() {
           const uid = p.display_unit_id
             ? String(p.display_unit_id)
             : canonicalUnitId(us, p.base_unit);
-          const uf = us.find((u) => String(u.id) === uid)?.factor || 1;
+          // Erfassungseinheit des Mindestbestands wiederherstellen.
-          const mode = p.package_size && p.package_size > 0 ? "package" : "unit";
+          const mode = p.min_stock_in_packages
-          const f = mode === "package" ? p.package_size : uf;
+            ? "package"
+            : p.min_stock_unit_id
+              ? String(p.min_stock_unit_id)
+              : uid;
+          const f = minFactor(mode, p.package_size, us);
           setMinUnit(mode);
           setForm({
             barcode: p.barcode || "", name: p.name, brand: p.brand || "",
@@ -148,9 +153,10 @@ export default function ProductForm() {
   }, [id]);
 
   function buildPayload() {
+    const sel = minUnit || form.unit_id;
     let minBase = null;
     if (form.min_stock !== "") {
-      minBase = Number(form.min_stock) * minFactor(minUnit, form.package_size, unitFactor);
+      minBase = Number(form.min_stock) * minFactor(sel, form.package_size, units);
     }
     return {
       barcode: form.barcode || null,
@@ -160,6 +166,8 @@ export default function ProductForm() {
       unit_id: form.unit_id === "" ? null : Number(form.unit_id),
       package_size: form.package_size === "" ? null : Number(form.package_size),
       min_stock: minBase,
+      min_stock_unit_id: sel === "package" || sel === "" ? null : Number(sel),
+      min_stock_in_packages: sel === "package",
       group_id: form.group_id === "" ? null : Number(form.group_id),
     };
   }
@@ -257,9 +265,11 @@ export default function ProductForm() {
               <div className="field-inline">
                 <input type="number" step="any" value={form.min_stock}
                   onChange={(e) => set("min_stock", e.target.value)} disabled={readOnly} placeholder="z.B. 2" />
-                <select value={minUnit} onChange={(e) => changeMinUnit(e.target.value)}
+                <select value={minUnit || form.unit_id} onChange={(e) => changeMinUnit(e.target.value)}
-                  disabled={readOnly} style={{ maxWidth: 150, marginTop: 0 }}>
+                  disabled={readOnly} style={{ maxWidth: 160, marginTop: 0 }}>
-                  <option value="unit">{unitName || "Einheit"}</option>
+                  {units
+                    .filter((u) => !selectedUnit || u.kind === selectedUnit.kind)
+                    .map((u) => <option key={u.id} value={u.id}>{u.name}</option>)}
                   {form.package_size && <option value="package">Packung(en)</option>}
                 </select>
               </div>

web/src/pages/Products.jsx

@@ -99,13 +99,7 @@ export default function Products() {
                     </td>
                     <td className="num muted">
                       {p.min_stock != null ? (
-                        <>
+                        <>{fmt(p.min_stock_display)} {p.min_stock_unit_label}</>
-                          {fmt(p.min_stock / (p.unit_factor || 1))}{" "}
-                          {p.unit_name || unitShort(p.base_unit)}
-                          {p.package_size ? (
-                            <span className="small"> · {fmt(p.min_stock / p.package_size)} Pkg</span>
-                          ) : null}
-                        </>
                       ) : "–"}
                     </td>
                     <td className="num"><Link to={`/products/${p.id}`}>Details</Link></td>