从泛型列表中检索值<在foreach语句中使用LINQ
本文关键字：语句 foreach LINQ 泛型 列表 检索 | 更新日期: 2023-09-27 18:15:35
我认为这是一个愚蠢的(简单的)问题，但我没能找到答案，我可以有效地使用LINQ的XML(这是我的LINQ经验的全部)，但当我试图从一个通用列表或列表(包括在描述)中获得实际值作为字符串时，我只得到像"{System.Linq.Enumerable。whereselectlisttiterator}"我想在这里写"scramble -eggs.jpg"
private static List<Recipe> currentRecipeList = new List<Recipe>();
public static List<Recipe> CurrentRecipeList { get { return currentRecipeList; } set { currentRecipeList = value; } }//Populated from an XML document
public static string GetSpecificRecipeValue(string recipeName, int index, int ingredientIteration = -1, int ingredientValue = -1)//From CurrentRecipeList get value(Index) where recipeName is equal to CurrentRecipeList.RecipeName.
{
IEnumerable<string> recipeElement = null;
IEnumerable<string> ingredientElement = null;
if (index == 0)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeType); }
else if (index == 1)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeName ); }
else if (index == 2)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeSource); }
else if (index == 3)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeID); }
else if (index == 4)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipePicture); }
else if (index == 5)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeDescription); }
else if (index == 6)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeMethod); }
else if (index == 7)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeCost); }
else if (index == 8)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeDifficulty); }
else if (index == 9)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeServings); }
else if (index == 10)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipePreparationTime); }
else if (index == 11)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeCookingTime); }
else if (index == 12)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeGlobalRating); }
else if (index == 13)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeUserRating); }
else if (index == 14)
{ recipeElement = (from el in currentRecipeList where el.RecipeName == recipeName select el.RecipeTags); }
else if (index == 15 && ingredientValue == 0)
{ ingredientElement = (from el in currentRecipeList where el.RecipeName == recipeName select el.RecipeIngredients[ingredientIteration].Item); }
else if (index == 15 && ingredientValue == 1)
{ ingredientElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeIngredients[ingredientIteration].Quantity); }
else if (index == 15 && ingredientValue == 2)
{ ingredientElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeIngredients[ingredientIteration].Unit.ToString()); }
else if (index == 15 && ingredientValue == 3)
{ ingredientElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeIngredients[ingredientIteration].State); }
else if (index == 15 && ingredientValue == 4)
{ ingredientElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeIngredients[ingredientIteration].Type); }
else
{ recipeElement = null; ingredientElement = null; }
if (recipeElement != null)
{
return recipeElement.ToString();
}
else if (ingredientElement != null)
{
return ingredientElement.ToString();
}
else
{
return null;
}
}
Recipe Class…
public class Recipe
{
public string RecipeType { get; set; }
public string RecipeName { get; set; }
public string RecipeSource { get; set; }
public string RecipeID { get; set; }
public string RecipePicture { get; set; }//File name of Picture to read from pictures folder
public string RecipeDescription { get; set; }//ShortDescription
public string RecipeMethod { get; set; }
public string RecipeCost { get; set; }
public string RecipeDifficulty { get; set; }
public string RecipeServings { get; set; }
public string RecipePreparationTime { get; set; }
public string RecipeCookingTime { get; set; }
public string RecipeGlobalRating { get; set; }
public string RecipeUserRating { get; set; }
public string RecipeTags { get; set; }
public List<Ingredient> RecipeIngredients { get; set; }
}
配料类…
public class Ingredient
{
public string Item { get; set; }
public string Quantity { get; set; }
public string Unit { get; set; }
public string State { get; set; }
public string Type { get; set; }
}
请让我知道如果你需要更多的信息，这是我的第一个帖子，虽然我已经绞尽脑汁，谷歌和stackoverflow，答案逃避我。从RecipeName中获取特定信息的任何其他方法，作为参数或来源，我可以自己学习这些信息，将非常感谢。
编辑好的，这是正确的解决方案作为返回结果感谢BJ迈尔斯。
private static List<Recipe> currentRecipeList = new List<Recipe>();
public static List<Recipe> CurrentRecipeList { get { return currentRecipeList; } set { currentRecipeList = value; } }//Populated from an XML document.
public static string GetSpecificRecipeValue(string recipeName, int index, int ingredientIteration = -1, int ingredientValue = -1)//From CurrentRecipeList get value(Index) where recipeName is equal to CurrentRecipeList.RecipeName.
{
IEnumerable<string> recipeElement = null;
IEnumerable<string> ingredientElement = null;
if (index == 0)
{ recipeElement = (from el in currentRecipeList where recipeName == el.RecipeName select el.RecipeType); }
else if (index == 1)
...
if (recipeElement != null)
{
string result = recipeElement.FirstOrDefault<string>().ToString();
return result;
}
else if (ingredientElement != null )
{
return ingredientElement.FirstOrDefault<string>().ToString();
}
else
{
return null;
}
答案:.FirstOrDefault from返回所需值，而不是实现IEnumerable的类。
string result = recipeElement.FirstOrDefault<string>().ToString();
return result;
答案，正如Thomas所提供的，是使用.FirstOrDefault()。但是，为了帮助您编写代码，我认为我应该向您展示一种更短的方法来完成您正在做的事情。试试这个:
public static string GetSpecificRecipeValue(string recipeName, int index, int ingredientIteration = -1, int ingredientValue = -1)//From CurrentRecipeList get value(Index) where recipeName is equal to CurrentRecipeList.RecipeName.
{
Func<Recipe, string>[] properties = new Func<Recipe, string>[]
{
el => el.RecipeType,
el => el.RecipeName,
el => el.RecipeSource,
el => el.RecipeID,
el => el.RecipePicture,
el => el.RecipeDescription,
el => el.RecipeMethod,
el => el.RecipeCost,
el => el.RecipeDifficulty,
el => el.RecipeServings,
el => el.RecipePreparationTime,
el => el.RecipeCookingTime,
el => el.RecipeGlobalRating,
el => el.RecipeUserRating,
el => el.RecipeTags,
};
Func<Recipe, string>[] ingredients = new Func<Recipe, string>[]
{
el => el.RecipeIngredients[ingredientIteration].Item,
el => el.RecipeIngredients[ingredientIteration].Quantity,
el => el.RecipeIngredients[ingredientIteration].Unit,
el => el.RecipeIngredients[ingredientIteration].State,
el => el.RecipeIngredients[ingredientIteration].Type,
};
return
currentRecipeList
.Where(el => recipeName == el.RecipeName)
.Select(el =>
index < 15
? properties[index](el)
: ingredients[ingredientValue](el))
.FirstOrDefault();
}