Django HTML模板无法读取嵌套字典中模型字段的问题求助

问题背景 #

在Django项目中，通过context字典传递嵌套结构数据到HTML模板时，无法显示视图传递的模型字段，仅输出{% empty %}分支内容。已确认数据库数据正确，QuerySet已存入字典并传递到模板。

相关代码 #

模型定义（models.py）

class Ingredients(models.Model):
    id = models.IntegerField(primary_key=True)
    recipe = models.ForeignKey(Recipes, on_delete=models.CASCADE, related_name='ingredients')
    ingredient = models.CharField(max_length=128)

    class Meta:
        managed = False
        db_table = 'ingredients'
        verbose_name_plural = 'Ingredients'

    def __str__(self):
        return f"{self.id} {self.recipe} - {self.ingredient}"

class Recipes(models.Model):
    id = models.IntegerField(primary_key=True)
    category = models.TextField(db_column='Category', null=False)
    submitted_by = models.TextField(
        db_column='Submitted_By', null=False)
    origin = models.TextField(db_column='Origin', null=False)
    title = models.TextField(db_column='Title', null=False)
    directions = models.TextField(
        db_column='Directions', null=False)
    comments = models.TextField(db_column='Comments', null=False)
    created = models.DateTimeField(null=False)
    modified = models.DateTimeField(null=True)

    def __str__(self):
        return f"{self.id} - {self.title}"

    class Meta:
        managed = False
        db_table = 'recipes'
        verbose_name_plural = 'Recipes'

视图代码（views.py）

recipes = Recipes.objects.all().order_by(
    "category", "title")

content['ingredients'] = {}
for recipe in recipes:
    ingredients = Ingredients.objects.filter(
        recipe=recipe.id).order_by("id")
    content['ingredients'][recipe.id] = ingredients
content['recipes'] = recipes

return render(
    request,
    "myApp/recipes.html",
    context=content)

模板代码（recipes.html）

{% for recipe in recipes %}
    <div id="id-{{recipe.id}}" class="grid-item {{recipe.category}} {{recipe.submitted_by}}">
        <div class="row">
            <div class="col-12 col-md-3 ingredients">
                {% for queryQbject in ingredients.recipe.id %}
                    {{ queryQbject.ingredient }}<br>
                {% empty %}
                    <span>No ingredients provided</span>
                {% endfor %}
            </div>
    </div>
{% endfor %}

错误原因 #

模板中ingredients.recipe.id的写法完全错误：ingredients是一个以菜谱ID为键的字典，而不是对象属性。这种写法无法正确获取对应菜谱的Ingredients QuerySet，导致进入{% empty %}分支。

解决方案 #

方案1：修复模板的字典取值方式 #

将模板中的循环行修改为以下两种写法之一：

写法A：使用Django模板的get过滤器

{% for item in ingredients|get:recipe.id %}
    {{ item.ingredient }}<br>
{% empty %}
    <span>No ingredients provided</span>
{% endfor %}

写法B：直接使用字典键取值（Django模板支持方括号语法）

{% for item in ingredients[recipe.id] %}
    {{ item.ingredient }}<br>
{% empty %}
    <span>No ingredients provided</span>
{% endfor %}

方案2：利用模型关联优化代码（更高效推荐） #

模型中已经定义了related_name='ingredients'，可以直接通过菜谱对象获取关联的食材，无需手动构建字典，还能避免N+1查询问题：

修改视图代码（views.py）

# 使用prefetch_related预取关联的ingredients，提升性能
recipes = Recipes.objects.all().order_by("category", "title").prefetch_related('ingredients')

content['recipes'] = recipes

return render(
    request,
    "myApp/recipes.html",
    context=content)

修改模板代码（recipes.html）

{% for recipe in recipes %}
    <div id="id-{{recipe.id}}" class="grid-item {{recipe.category}} {{recipe.submitted_by}}">
        <div class="row">
            <div class="col-12 col-md-3 ingredients">
                {% for item in recipe.ingredients.all %}
                    {{ item.ingredient }}<br>
                {% empty %}
                    <span>No ingredients provided</span>
                {% endfor %}
            </div>
    </div>
{% endfor %}

说明 #

方案2不仅简化了代码，还通过prefetch_related一次性加载所有关联数据，避免了循环中多次查询数据库的性能问题，是更推荐的实现方式。

内容的提问来源于stack exchange，提问作者Volker Petersen