休眠多對多的映射和查詢去與它

Question

我有一些麻煩得到HQL的掛鉤。我有一個應用程序，我在一張桌子上有一堆競爭對手。然後我有比賽，在那裏我匹配競爭對手。每個競賽可能有許多競爭對手。每個參賽者可能會參加多項比賽。 （事實上​​，我正在組織一場「循環賽」比賽，因此所有參賽者都將參加很多比賽，以確保他們能夠與其他所有參賽者一起比賽。）

我自己並沒有創建連接表使用Hibernate的XML來創建連接表。最後，我想我應該能夠編寫類似下面的HQL查詢：

這實際上是一個更大的查詢的一部分

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

簡單的查詢。我的意圖是計算給定參賽者參賽的比賽數量。我遇到的問題雖然是錯誤，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 ] 

這裏是我的競爭和競爭對手的映射。

競爭

<?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

查詢使用爲引用的語法（多對一），但一個/多到許多需要顯式連接有一個別名元素

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