feat: init backend

src/backend/items/serializers.py

@@ -0,0 +1,79 @@
+from rest_framework import serializers
+from django.contrib.auth.models import User
+from .models import Item, ItemUsage, Category
+
+
+class UserSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = User
+        fields = ['id', 'username', 'first_name', 'last_name', 'email']
+
+
+class CategorySerializer(serializers.ModelSerializer):
+    class Meta:
+        model = Category
+        fields = ['id', 'name', 'description', 'created_at']
+
+
+class ItemSerializer(serializers.ModelSerializer):
+    current_user = serializers.SerializerMethodField()
+
+    class Meta:
+        model = Item
+        fields = [
+            'id', 'name', 'description', 'serial_number', 'category', 'status',
+            'location', 'purchase_date', 'value', 'created_at', 'updated_at',
+            'current_user'
+        ]
+
+    def get_current_user(self, obj):
+        """获取当前正在使用该物品的用户"""
+        current_usage = ItemUsage.objects.filter(
+            item=obj, is_returned=False
+        ).first()
+        if current_usage:
+            return UserSerializer(current_usage.user).data
+        return None
+
+
+class ItemUsageSerializer(serializers.ModelSerializer):
+    user = UserSerializer(read_only=True)
+    user_id = serializers.IntegerField(write_only=True)
+    item = ItemSerializer(read_only=True)
+    item_id = serializers.IntegerField(write_only=True)
+
+    class Meta:
+        model = ItemUsage
+        fields = [
+            'id', 'item', 'item_id', 'user', 'user_id', 'start_time', 'end_time',
+            'purpose', 'notes', 'is_returned', 'condition_before', 'condition_after',
+            'created_at'
+        ]
+
+    def create(self, validated_data):
+        # 当创建新的使用记录时，更新物品状态为使用中
+        item = Item.objects.get(id=validated_data['item_id'])
+        item.status = 'in_use'
+        item.save()
+        return super().create(validated_data)
+
+    def update(self, instance, validated_data):
+        # 当归还物品时，更新物品状态为可用
+        if validated_data.get('is_returned', False) and not instance.is_returned:
+            item = instance.item
+            item.status = 'available'
+            item.save()
+        return super().update(instance, validated_data)
+
+
+class ItemDetailSerializer(ItemSerializer):
+    """物品详情序列化器，包含使用历史"""
+    usage_history = serializers.SerializerMethodField()
+
+    class Meta(ItemSerializer.Meta):
+        fields = ItemSerializer.Meta.fields + ['usage_history']
+
+    def get_usage_history(self, obj):
+        """获取物品的使用历史"""
+        usages = ItemUsage.objects.filter(item=obj).order_by('-start_time')[:10]
+        return ItemUsageSerializer(usages, many=True).data