我有一个Linq查询，试图根据位于CSV文件中的选定膳食类型过滤数据。CSV文件正在由CsvHelper处理，并由相关模型文件表示。
如下图所示，当我选择早餐（或午餐、晚餐或小吃）时，它不返回任何数据。
Linq查询：

public partial class EternityDataView : IGenerateNutritionalValues {
    private NutritionDataView dataView = new();
    public decimal? GetCalorieValues()
    {
        var calories = from c in FileUpload.records
            where c.Meal == dataView.SelectedMeal
            select c.Calories;

        return calories.Sum();
    }

字符串
NutritionDataView膳食选择剃须刀内容：

<div class="meal-select">
    <label for="meal-select">Select meal type:</label>
    <select name="meal-select" id="meal-select" @bind="SelectedMeal">
        <option value="all-meals">All meals</option>
        <option value="breakfast">Breakfast</option>
        <option value="dinner">Dinner</option>
        <option value="lunch">Lunch</option>
        <option value="snacks">Snacks</option>
    </select>
</div>
.......
// Switch for date range
    case "eternity":
        if (SelectedMeal == "all-meals")
        {
            <EternityDataViewAllMeals/>
        }
        else
        {
            <EternityDataView/>
        }
        break;

型
EternityDataView组件运行的图片，早餐选择为SelectedMeal：

EternityDataViewAllMeals组件运行的图片，其中所有膳食都被选为SelectedMeal：

的
CSV示例：

Date,Meal,Calories,Fat (g),Saturated Fat,Polyunsaturated Fat,Monounsaturated Fat,Trans Fat,Cholesterol,Sodium (mg),Potassium,Carbohydrates (g),Fiber,Sugar,Protein (g),Vitamin A,Vitamin C,Calcium,Iron,Note
2023-03-02,Breakfast,105.0,0.4,0.1,0.1,0.0,0.0,0.0,1.2,422.4,27.0,3.1,14.4,1.3,5.0,17.1,0.6,1.7,
2023-03-02,Lunch,710.0,30.1,3.2,0.1,0.0,0.0,0.0,2.8,214.0,91.8,9.8,44.4,18.1,0.0,15.3,1.2,1.3,
2023-03-02,Dinner,699.8,29.4,7.8,2.4,6.2,0.2,19.8,268.3,180.4,87.2,3.4,28.6,22.6,12.7,84.1,15.8,2.0,
2023-03-02,Snacks,166.0,0.4,0.0,0.1,0.1,0.0,0.0,6.9,615.7,39.6,1.0,28.7,2.4,0.0,193.7,19.4,2.5,

型
我有点困惑。正如你在图片中看到的，你可以看到value属性显示在下拉列表的下面，我用它作为一个调试工具。在Linq查询中，我设置了断点，发现SelectedMeal为null。所以我不太确定那里发生了什么。值得注意的是，对于所有的餐，EternityDataViewAllMeals中的Linq查询只是选择所有内容，而不关心日期。我不知道为什么SelectedMeal为null。
也许我需要分组？