休眠多对多的映射和查询去与它

Question

我有一些麻烦得到HQL的挂钩。我有一个应用程序，我在一张桌子上有一堆竞争对手。然后我有比赛，在那里我匹配竞争对手。每个竞赛可能有许多竞争对手。每个参赛者可能会参加多项比赛。 （事实上​​，我正在组织一场“循环赛”比赛，因此所有参赛者都将参加很多比赛，以确保他们能够与其他所有参赛者一起比赛。）

我自己并没有创建连接表使用Hibernate的XML来创建连接表。最后，我想我应该能够编写类似下面的HQL查询：

这实际上是一个更大的查询的一部分

select count(*) from Competition c where c.competitor.id = :competitorId 

简单的查询。我的意图是计算给定参赛者参赛的比赛数量。我遇到的问题虽然是错误，如：

org.hibernate.QueryException: could not resolve property: competitor of: com.sodapopsoftware.imagewar.model.db.Competition [ select count(*) from com.sodapopsoftware.imagewar.model.db.Competition c where c.competitor.id = :competitorId ] 

这里是我的竞争和竞争对手的映射。

竞争

<?xml version="1.0"?> 
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" 
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> 
<hibernate-mapping> 
<class name="com.sodapopsoftware.imagewar.model.db.Competition" table="competition"> 

    <meta attribute="use-in-tostring">true</meta> 
    <meta attribute="extra-import">java.util.Set</meta> 
    <meta attribute="extra-import">java.util.TreeSet</meta> 

    <id name="competitionId" column="competition_id" type="int"> 
     <meta attribute="scope-set">protected</meta> 
     <meta attribute="field-description">Primary Key</meta> 
     <meta attribute="use-in-equals">true</meta> 
     <generator class="native" /> 
    </id> 
    <many-to-one name="league" column="league_id" unique="false" not-null="true" 
     class="com.sodapopsoftware.imagewar.model.db.League" 
    /> 
    <property name="dateAdded" column="date_added" type="date" not-null="true"> 
     <meta attribute="field-description">When the league was created</meta> 
    </property> 
    <set name="competitors" table="competition_competitors" sort="com.sodapopsoftware.imagewar.model.util.CompetitorIdComparator"> 
     <meta attribute="property-type"><![CDATA[Set<Competitor>]]></meta> 
     <meta attribute="default-value"><![CDATA[new TreeSet<Competitor>()]]></meta> 
     <key column="competition_id"/> 
     <many-to-many column="competitor_id" 
      unique="false" 
      class="com.sodapopsoftware.imagewar.model.db.Competitor"/> 
    </set> 
</class> 
</hibernate-mapping> 

COMPETITOR

<?xml version="1.0"?> 
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" 
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> 
<hibernate-mapping> 
<class name="com.sodapopsoftware.imagewar.model.db.Competitor" table="competitor"> 

    <meta attribute="use-in-tostring">true</meta> 
    <meta attribute="extra-import">java.lang.Comparable</meta> 
    <meta attribute="implements">Comparable<![CDATA[<]]> Competitor <![CDATA[>]]></meta> 
    <meta attribute="class-code"> private static final long serialVersionUID = 1L;</meta> 
    <meta attribute="class-code"> 
public int compareTo(Competitor that) { 
    if (that != null) { 
     return this.getCompetitorId() - that.getCompetitorId(); 
    } 
    return 1; 
} 
    </meta> 
    <id name="competitorId" column="competitor_id" type="int"> 
     <meta attribute="scope-set">protected</meta> 
     <meta attribute="use-in-equals">true</meta> 
     <generator class="native" /> 
    </id> 
    <many-to-one name="league" column="league_id" unique="false" not-null="true" 
     class="com.sodapopsoftware.imagewar.model.db.League" 
    /> 
    <property name="name" column="name" type="string" not-null="true"> 
     <meta attribute="field-description">Gives this competitor a name</meta> 
    </property> 
    <property name="nameNormalized" column="name_normalized" unique="true" type="string" not-null="true"> 
     <meta attribute="field-description">Same as name, but lower case for searching</meta> 
    </property> 
    <property name="description" column="description" type="string"> 
     <meta attribute="field-description">Describes this competitor</meta> 
    </property> 
    <property name="linkImageThumbnail" column="link_image_thumbnail" type="string" not-null="true"> 
     <meta attribute="field-description">Link to the thumbnail image for this competitor</meta> 
    </property> 
    <property name="linkImageFullSized" column="link_image_full_sized" type="string" not-null="true"> 
     <meta attribute="field-description">Link to the full-sized image for this competitor</meta> 
    </property> 
    <property name="dateAdded" column="date_added" type="date" not-null="true"> 
     <meta attribute="field-description">When the competitor was created</meta> 
    </property> 
</class> 
</hibernate-mapping> 

Answer 1

查询使用为引用的语法（多对一），但一个/多到许多需要显式连接有一个别名元素

select count(*) from Competition c join c.competitors co where co.id = :competitorId