Question

我为NHibernate设置了持久性的以下域名： Domain

我使用PaperConfiguration作为根聚合。

我想为给定的Tier和AcademicYearConfiguration选择所有PaperConfiguration对象。根据以下示例，这非常有效：

ICriteria criteria =
session.CreateCriteria<PaperConfiguration>()
    .Add(Restrictions.Eq("AcademicYearConfiguration", configuration))
    .CreateCriteria("Paper")
    .CreateCriteria("Unit")
    .CreateCriteria("Tier")
        .Add(Restrictions.Eq("Id", tier.Id))

return criteria.List<PaperConfiguration>();

（也许有更好的方法可以做到这一点。）

然而，还需要知道每个PaperConfiguration有多少ReferenceMaterials，我想在同一个调用中得到它。避免使用HQL - 我已经有了HQL解决方案。

我知道这是预测的内容，this question提出了一个想法，但我无法让它发挥作用。

我有一个PaperConfigurationView，而不是IList<ReferenceMaterial> ReferenceMaterials ReferenceMaterialCount，并且正在思考

ICriteria criteria =
session.CreateCriteria<PaperConfiguration>()
    .Add(Restrictions.Eq("AcademicYearConfiguration", configuration))
    .CreateCriteria("Paper")
    .CreateCriteria("Unit")
    .CreateCriteria("Tier")
        .Add(Restrictions.Eq("Id", tier.Id))
    .SetProjection(
        Projections.ProjectionList()
           .Add(Projections.Property("IsSelected"), "IsSelected")
           .Add(Projections.Property("Paper"), "Paper")
            // and so on for all relevant properties
           .Add(Projections.Count("ReferenceMaterials"), "ReferenceMaterialCount")
    .SetResultTransformer(Transformers.AliasToBean<PaperConfigurationView>());

return criteria.List< PaperConfigurationView >();

不幸的是，这不起作用。我做错了什么？

以下简化查询：

ICriteria criteria =
session.CreateCriteria<PaperConfiguration>()
.CreateCriteria("ReferenceMaterials")
.SetProjection(
Projections.ProjectionList()
.Add(Projections.Property("Id"), "Id")
.Add(Projections.Count("ReferenceMaterials"), "ReferenceMaterialCount")
).SetResultTransformer(Transformers.AliasToBean<PaperConfigurationView>());
 return criteria.List< PaperConfigurationView >();

创建了这个意外的SQL：

SELECT 
  this_.Id as y0_, 
  count(this_.Id) as y1_ 
FROM Domain.PaperConfiguration this_ 
  inner join Domain.ReferenceMaterial referencem1_ 
    on this_.Id=referencem1_.PaperConfigurationId

上述查询因ADO.NET错误而失败，因为它显然不是正确的SQL，因为它缺少group by或count is count（referencem1_.Id）而不是（this_.Id）。

NHibernate映射：

  <class name="PaperConfiguration" table="PaperConfiguration">
    <id name="Id" type="Int32">
      <column name="Id" sql-type="int" not-null="true" unique="true" index="PK_PaperConfiguration"/>
      <generator class="native" />
    </id>
    <!-- IPersistent -->
    <version name="VersionLock" />
    <!-- IAuditable -->
    <property name="WhenCreated" type="DateTime" />
    <property name="CreatedBy" type="String" length="50" />
    <property name="WhenChanged" type="DateTime" />
    <property name="ChangedBy" type="String" length="50" />

    <property name="IsEmeEnabled" type="boolean" not-null="true" />

    <property name="IsSelected" type="boolean" not-null="true" />

    <many-to-one name="Paper" column="PaperId" class="Paper" not-null="true" access="field.camelcase"/>

    <many-to-one name="AcademicYearConfiguration" column="AcademicYearConfigurationId" class="AcademicYearConfiguration" not-null="true" access="field.camelcase"/>

    <bag name="ReferenceMaterials" generic="true" cascade="delete" lazy="true" inverse="true">
      <key column="PaperConfigurationId" not-null="true" />
      <one-to-many class="ReferenceMaterial" />
    </bag>
  </class>

  <class name="ReferenceMaterial" table="ReferenceMaterial">
    <id name="Id" type="Int32">
      <column name="Id" sql-type="int" not-null="true" unique="true" index="PK_ReferenceMaterial"/>
      <generator class="native" />
    </id>
    <!-- IPersistent -->
    <version name="VersionLock" />
    <!-- IAuditable -->
    <property name="WhenCreated" type="DateTime" />
    <property name="CreatedBy" type="String" length="50" />
    <property name="WhenChanged" type="DateTime" />
    <property name="ChangedBy" type="String" length="50" />

    <property name="Name" type="String" not-null="true" />
    <property name="ContentFile" type="String" not-null="false" />
    <property name="Position" type="int" not-null="false" />
    <property name="CommentaryName" type="String" not-null="false" />
    <property name="CommentarySubjectTask" type="String" not-null="false" />
    <property name="CommentaryPointScore" type="String" not-null="false" />
    <property name="CommentaryContentFile" type="String" not-null="false" />

    <many-to-one name="PaperConfiguration" column="PaperConfigurationId" class="PaperConfiguration" not-null="true"/>
  </class>

Answer 1

您应该使用Projections.GroupProperty（）而不是Projections.Property（）。

使用NHibernate Criteria API选择特定的数据集和计数

1 个答案: