Entity Framework Core：检查逗号分隔的字符串是否包含列表中的任何值

Question

我有下表：

recipe            

id  | ingredients     
----+--------------
 1  | "1,2,3"          
 2  | "3,4"           
 3  | "2"        
 4  | "1,2,3,4" 

我想找到所有含有成分“1”、“3”或“4”的食谱。如何使用 Entity Framework Core 实现这一目标？

这是我尝试过的，但似乎这个表达不可翻译：

var ingredientIds = new List<string> {"1", "3", "4"};

var recipes = dbContext.Set<Recipe>
                       .Where(x => x.IngredientIds.Split(',', StringSplitOptions.None).Any(y => ingredientIds.Contains(y))
                       .ToList();

Answer 1

嗯，您首先不应该使用逗号分隔值，这就是导致问题的原因。

解决方案是更改数据库设计，以在配方和成分之间创建适当的多对多关系。

在数据库优先设计中，您将添加一个 IngredientToRecipe 表：

CREATE TABLE IngredientToRecipe 
(
    recepieId int NOT NULL,
    IngredientId int NOT NULL,
    CONTRAINT PrimaryKey Pk_IngredientToRecipe (recepieId, IngredientId)
)

在代码优先设计中，您必须将导航属性作为集合添加到实体中：

class Recipe
{
  public List<Ingredient> Ingredients {get;set;}
  // other properties here
}

class Ingredient
{
  public List<Recipe> Recipes {get;set;}
  // other properties here
}

EF Core 将知道如何将其转换为多对多关系。

Answer 2

var newrecipes = (from r1 in recipes
                  from i in ingredients
                  where r1.IngredientIds.Contains(i.Id.ToString())
                  select new { recipe = r1.Id, ingedientId = i.Id, ingredientName = i.Name }
                  );
foreach (var item in newrecipes )
{
System.Console.WriteLine($"recipe {item.recipe}: ingredient: {item.ingedientId}, {item.ingredientName}");
}

输出（当使用您其他问题的数据时：Entity Framework - Join Comma Separed List）：

recipe 1: ingredient: 1, flour
recipe 1: ingredient: 2, sugar
recipe 1: ingredient: 3, egg
recipe 2: ingredient: 3, egg
recipe 2: ingredient: 4, butter
recipe 3: ingredient: 2, sugar
recipe 4: ingredient: 1, flour
recipe 4: ingredient: 2, sugar
recipe 4: ingredient: 3, egg
recipe 4: ingredient: 4, butter