问题
I have simple situation (like on the image link text) and simple SQL query
SELECT M.Name,
A.Name,
B.Name
FROM Master M LEFT JOIN DetailA A
ON M.DescA = A.Id LEFT JOIN DetailB B
ON M.DescB = B.Id
How to achive the same effect in nHibernate using CriteriaAPI ?
I have something like this:
public class Employee : ClassBase, IContactData
{
public virtual string FirstName { get; set; }
public virtual string MiddleName { get; set; }
public virtual string LastName { get; set; }
public virtual string NickName { get; set; }
public virtual string Login { get; set; }
public virtual string Password { get; set; }
public virtual string ContactPerson { get; set; }
public virtual string PESEL { get; set; }
public virtual string IdentificationNo { get; set; }
public virtual string NIP { get; set; }
public virtual string Description { get; set; }
public virtual string Profession { get; set; }
public virtual byte[] Photo { get; set; }
public virtual DateTime? BirthDate { get; set; }
public virtual Boolean SpecialUser { get; set; }
public virtual Boolean Sex { get; set; }
public virtual Item Gender { get; set; }
public virtual Item Position { get; set; }
public virtual Item Status { get; set; }
public virtual Item Nation { get; set; }
public virtual Item Education { get; set; }
public virtual Item JobType { get; set; }
public virtual ISet<Address> Addresses { get; set; }
}
public class Item : ClassBase
{
public virtual int ItemCode { get; set; }
public virtual int DictCode{ get; set;}
public virtual string Description{ get; set;}
public override string ToString()
{
return Description;
}
}
public class Address : ClassBase
{
public virtual string Description { get; set; }
public virtual string District { get; set; }
public virtual string Community { get; set; }
public virtual string City { get; set; }
public virtual string Street { get; set; }
public virtual string PostalCode { get; set; }
public virtual string HouseNo { get; set; }
public virtual string FlatNo { get; set; }
public virtual Boolean Official { get; set; }
public virtual Item Country { get; set; }
public virtual Item Region { get; set; }
}
Mappings:
<property name="FirstName" column="FIRST_NAME" type="string" length="50" not-null="true"/>
<property name="MiddleName" column="MIDDLE_NAME" type="string" length="50" not-null="false"/>
<property name="LastName" column="LAST_NAME" type="string" length="50" not-null="true"/>
<property name="NickName" column="NICKNAME" type="string" length="50" not-null="false"/>
<property name="Login" column="LOGIN" type="string" length="30" not-null="false"/>
<property name="Password" column="PASSWORD" type="string" length="100" not-null="false"/>
<property name="ContactPerson" column="CONTACT_PERSON" type="string" length="250" not-null="false"/>
<property name="PESEL" column="PESEL" type="string" length="11" not-null="false"/>
<property name="IdentificationNo" column="IDENTIFICATION_NO" type="string" length="12" not-null="false"/>
<property name="NIP" column="NIP" type="string" length="11" not-null="false"/>
<property name="Description" column="DESCRIPTION" type="string" length="1000" not-null="false"/>
<property name="Profession" column="PROFESSION" type="string" length="150" not-null="false"/>
<property name="BirthDate" column="BIRTH_DATE" type="DateTime" not-null="false"/>
<property name="Photo" column="PHOTO" type="BinaryBlob" not-null="false"/>
<property name="Sex" column="SEX" type="Boolean" not-null="false"/>
<property name="SpecialUser" column="SPECIAL_USER" type="Boolean" not-null="false"/>
<many-to-one name="Gender" column="DIC_GENDER" not-null="false" class="DomainModel.ERP.Item,DomainModel" />
<many-to-one name="Position" column="DIC_POSITION" not-null="false" class="DomainModel.ERP.Item,DomainModel" />
<many-to-one name="Status" column="DIC_STATUS" not-null="false" class="DomainModel.ERP.Item,DomainModel" />
<many-to-one name="Nation" column="DIC_NATION" not-null="false" class="DomainModel.ERP.Item,DomainModel" />
<many-to-one name="Education" column="DIC_EDUCATION" not-null="false" class="DomainModel.ERP.Item,DomainModel" />
<many-to-one name="JobType" column="DIC_JOB_TYPE" not-null="false" class="DomainModel.ERP.Item,DomainModel" />
<set name="Addresses" table="TBL_ADDRESS" generic="true">
<key column="FK_EMPLOYEE" />
<one-to-many class="DomainModel.ERP.HRM.Address,DomainModel"/>
</set>
<property name="ItemCode" column="ITEM_CODE" type="integer" not-null="true"/>
<property name="DictCode" column="TABLE_CODE" type="integer" not-null="true"/>
<property name="Description" column="NAME" type="string" length="200" not-null="true"/>
<version name="Version" column="VERSION" type="integer" unsaved-value="0"/>
<property name="Description" column="DESCRIPTION" type="string" length="1000" not-null="false"/>
<property name="District" column="DISTRICT" type="string" length="15" not-null="false"/>
<property name="Community" column="COMMUNITY" type="string" length="150" not-null="false"/>
<property name="City" column="CITY" type="string" length="150" not-null="true"/>
<property name="Street" column="STREET" type="string" length="150" not-null="true"/>
<property name="PostalCode" column="POSTAL_CODE" type="string" length="10" not-null="false"/>
<property name="HouseNo" column="HOUSENO" type="string" length="20" not-null="true"/>
<property name="FlatNo" column="FLATNO" type="string" length="20" not-null="false"/>
<property name="Official" column="IS_OFFICIAL" type="Boolean" not-null="true"/>
<many-to-one name="Country" column="DIC_COUNTRY" not-null="false" class="DomainModel.ERP.Item,DomainModel" />
<many-to-one name="Region" column="DIC_REGION" not-null="false" class="DomainModel.ERP.Item,DomainModel" />
I need :
- Retrive data to my grid Control
- - FirstName,
- - LastName,
- - NIP,
- - Position.Description,
- - Education.Description,
- - JobType.Description,
- - Country.Description - from Addresses where Address.Official is true,
- - Street - from Addresses where Address.Official is true,
- - HouseNo - from Addresses where Address.Official is true,
- - FlatNo - from Addresses where Address.Official is true.
- Retrive data to another grid Control
- - FirstName,
- - LastName,
- - NIP,
- - Position.Description,
- - Education.Description,
- - JobType.Description.
and the most important think. I want to do this using only one SELECT statement. Now for point 1 I use NamedSQLQuery and everything is working grate but for simplest situation I want use CriteriaAPI.
Also for point 1 and 2 I have DTO classes and I transform result of query to this classes.
I can do this by GetAllEmployees() but many properties is Lazy Loaded and doing that I have a huge trafic between application and database. I can change these properties to Eager Loading but in my opinion there is too much data to retrive which I don't need.
回答1:
I've found my solution :)
var master = DetachedCriteria.For<Master>()
.CreateAlias("DetailA", "detA", JoinType.LeftOuterJoin)
.CreateAlias("DetailB", "detB", JoinType.LeftOuterJoin)
.SetProjection
(
Projections.ProjectionList()
.Add(Projections.Property("Id"), "Id")
.Add(Projections.Property("Name"), "MasterName")
.Add(Projections.Property("detA.Name"), "DetailAName")
.Add(Projections.Property("detB.Name"), "DetailBName")
)
.SetResultTransformer(Transformers.AliasToBean(typeof (MasterDTO)));
class MasterDTO
{
public virtual int Id {get;set;}
public virtual string MasterName {get;set;}
public virtual string DetailAName {get;set;}
public virtual string DetailBName {get;set;}
public MasterDTO()
{}
public MasterDTO(int id, string mastername, string detailaname, string detailbname)
{
Id = id;
MasterName = mastername;
DetailAName = detailaname;
DetailBName = detailbname;
}
}
回答2:
My advice for this type of situation - where you want to display a grid with data from multiple entities, just create an sql view and map that with NH.
You will be much happier in the long run.
来源：https://stackoverflow.com/questions/2917490/nhibernate-join-and-projection-properties