要求- 对于食谱应用程序，用户可以输入食谱名称和成分。用户可以在JSP页面上输入食谱的多种成分。
数据库模型：创建了 2 个表。 （食谱可以有不止一种成分）
Recipe -
recipe_id (primary key)
name
Ingredient
ingredient_id (primary key)
recipe_id (foreign key to recipe(recipe_id))
quantity
ingredient
Issue- 对于这种情况，@OneToMany（如下所示）用于 Hibernate 映射，但是当用户保存表单时，外键（即recipe_id）未存储在成分表中。
假设用户输入以下内容：
Recipe - Sandwich
Ingredient - 250g(as quantity) Salt (as ingredient)
保存后，以下内容将被保存（即配方表中没有值）
**Recipe**
recipe_id - 1
name - Sandwich
**Ingredient**
ingredient_id - 50
recipe_id - NULL
quantity - 250g
ingredient - Salt
保存表单时没有错误。
当用户保存数据时，Hibernate 会将以下内容保存在日志中：
Hibernate: select seq_recipe.nextval from dual
Hibernate: select seq_ingredient.nextval from dual
Hibernate: insert into RECIPE (NAME, RECIPE_ID) values (?, ?)
Hibernate: insert into ingredient (COMMENTS, INGREDIENT, RECIPE_ID, INGREDIENT_ID) values (?, ?, ?, ?)
甲骨文表
create table ingredient(ingredient_id number(4) primary key,
quantity varchar2(20),
ingredient varchar2(40),
recipe_id number(4),
constraint recipe_fk foreign key (recipe_id)
references recipe(recipe_id));
create table recipe(id number primary key,
name varchar2(25) unique,
ingredient_id number(4),
constraint ingredient_fk foreign key(ingredient_id)
references ingredient(ingredient_id));
成分和配方 POJO
@Entity
@Table(name = "ingredient", uniqueConstraints={
@UniqueConstraint(columnNames="INGREDIENT_ID")
})
public class Ingredient implements Serializable {
private static final long serialVersionUID = -2489479702169761646L;
@Id
@Column(name = "INGREDIENT_ID", unique=true, nullable=false)
@SequenceGenerator(name="seq_ingredient", sequenceName="seq_ingredient")
@GeneratedValue(strategy=GenerationType.AUTO, generator="seq_ingredient")
private Integer ingredientId;
@Column(name = "QUANTITY")
private String quantity;
@Column(name = "INGREDIENT")
private String ingredient;
@ManyToOne(fetch=FetchType.EAGER)
@JoinColumn(name="RECIPE_ID", nullable=false)
private Recipe recipe;
//getter and setters
@Entity
@Table(name = "recipe")
public class Recipe implements Serializable {
private static final long serialVersionUID = 4398676897855994030L;
@Id
@Column(name = "id")
private Integer id;
@Column(name = "name")
private String name;
@OneToMany(cascade=CascadeType.ALL, fetch=FetchType.EAGER, mappedBy="recipe")
private List<Ingredient> ingredients;
//getters and setter
}
当用户保存数据时，MVC 将映射 /add url 并处理 POST 方法
@RequestMapping("/add")
public String newRecipe(Model model) {
Recipe recipe = new Recipe();
recipe.setIngredients(new AutoPopulatingList<Ingredient>(Ingredient.class));
model.addAttribute("recipe", recipe);
return "recipes/new";
}
@RequestMapping(value = "add", method = RequestMethod.POST)
public String addRecipe(@Valid Recipe recipe, BindingResult result,
Model model) {
if (result.hasErrors()) {
return "recipes/new";
}
recipeServices.addRecipe(recipe);
return "redirect:/recipe/" + recipe.getId();
}
**用于保存配方对象的 DAO **
public class RecipeDaoImpl implements RecipeDao {
public void addRecipe(Recipe recipe) {
getSession().save(recipe);
}
}
JSP code
<html>
<script type="text/javascript">
<!--
function addRow(tableID) {
<!-- Code delete to improve readability. Dynamically add row -->
}
-->
</script>
</head>
<body>
<s:url value="/recipe/add" var="recipe_new" />
<sf:form modelAttribute="recipe" action="${recipe_new}" method="POST">
<table>
<tr>
<th>Recipe Name:</th>
<td><sf:input path="name" id="recipeName" /> <br />
<sf:errors path="name" cssClass="error" /></td>
</tr>
<tr>
<td>
<h3>Ingredients</h3> <INPUT type="button" value="+"
onclick="addRow('dataTable')" /> <INPUT type="button" value="-"
onclick="deleteRow('dataTable')" />
<table id="dataTable" width="350px" border="1">
<tr>
<th></th>
<th>Quantity</th>
<th>Ingredient</th>
</tr>
<tr>
<td><input type="checkbox" name="chk" /></td>
<td><sf:input type="text" path="ingredients[0].quantity"
title="Quantity" placeholder="Quantity" /></td>
<td><sf:input type="text" path="ingredients[0].ingredient"
title="Ingredient" placeholder="Ingredient" /></td>
</tr>
</table>
</td>
</tr>
</table>
</sf:form>
</body>
</html>
谦虚地请求帮助我，因为过去两天我一直在尝试解决这个问题，但无法理解为什么外键没有存储在数据库中。
