我有一个在MySql中运行的查询，但我试图在Nhibernate中使用它，我面临问题，因为我是Nhibernate的菜鸟。
SELECT transaction_table.transaction_id,transaction_table.amount,transaction_table.reason,transaction_table.transaction_datetime,g.status,
(CASE
WHEN (transaction_table.user_from IN(0)) THEN 'Paypal'
when (transaction_table.user_from<>0) THEN u.user_fullname
END)as user_name_from ,
(CASE
WHEN (transaction_table.user_to IN(0)) THEN 'Paypal'
when (transaction_table.user_to<>0) THEN us.user_fullname
END)as user_name_to
FROM transaction_table
left outer join users u on u.user_id=transaction_table.user_from
left outer join users us on transaction_table.user_to=us.user_id
left join gateway_table g on g.gateway_table_id=transaction_table.gateway_table_id
这是查询，
var results = session.QueryOver<TransactionTable>(() => transactionAlias)
.Left.JoinAlias(pr => pr.UserFrom, () => usersFromAlias.Id)
.Left.JoinAlias(pr => pr.UserTo, () => usersToAlias.Id)
.Left.JoinAlias(pr => pr.GatewayTableId, () => gatewayAlias.GatewayTableId)
.SelectList(list => list
.Select(pr => pr.TransactionId)
.Select(pr => pr.Amount)
.Select(pr => pr.Reason)
.Select(pr => pr.TransactionDatetime)
.Select(pr => pr.GatewayTableId)
.Select(Projections.Conditional(
Restrictions.Eq(
Projections.Property(() => transactionAlias.UserFrom), 0),
Projections.Constant("Paypal"),
Projections.Property(() => usersFromAlias.FullName)
))
.Select(Projections.Conditional(
Restrictions.Eq(
Projections.Property(() => transactionAlias.UserTo), 0),
Projections.Constant("Paypal"),
Projections.Property(() => usersToAlias.FullName)
)))
.List<object[]>();
在此之后我无法弄清楚如何继续，这是我一直在实施的中途。我找不到可靠的东西，关于XML我的映射可能是关系未映射的问题，我无法想象该怎么做。
下面的映射：
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="EWalletModule" namespace="EWalletModule">
<!-- User Table -->
<class name="Users" table="Users">
<id name="Id" column="user_id" type="int">
<generator class="native"></generator>
</id>
<property name="FullName" column="user_fullname" type="String"></property>
<property name="Email" column="user_email" type="String"></property>
<property name="Password" column="user_password" type="String"></property>
<property name="CreatedDatetime" column="created_datetime" type="datetime"></property>
</class>
<!-- Transaction Table -->
<class name="TransactionTable" table="transaction_table">
<id name="TransactionId" column="transaction_id" type="int">
<generator class="native"></generator>
</id>
<property name="GatewayTableId" column="gateway_table_id" type="int"></property>
<property name="UserFrom" column="user_from" type="String"></property>
<property name="UserTo" column="user_to" type="String"></property>
<property name="Amount" column="amount" type="String"></property>
<property name="Reason" column="reason" type="String"></property>
<property name="TransactionDatetime" column="transaction_datetime" type="datetime"></property>
</class>
<!-- Gateway Table -->
<class name="GatewayTable" table="gateway_table">
<id name="GatewayTableId" column="gateway_table_id" type="int">
<generator class="native"></generator>
</id>
<property name="Status" column="status" type="String"></property>
</class>
<!-- Wallet Table -->
<class name="WalletTable" table="user_wallet">
<id name="UserWalletId" column="user_wallet_id" type="int">
<generator class="native"></generator>
</id>
<property name="UserId" column="user_id" type="int"></property>
<property name="WalletBalance" column="wallet_balance" type="float"></property>
</class>
<!-- ManageWallet Table //For Admin -->
<class name="ManageWalletTable" table="manage_wallet">
<id name="ManageWalletId" column="manage_wallet_id" type="int">
<generator class="native"></generator>
</id>
<property name="TransactionFee" column="transaction_fee" type="float"></property>
<property name="WithdrawalFee" column="withdrawal_fee" type="float"></property>
<property name="Tax" column="tax" type="float"></property>
</class>
</hibernate-mapping>
表格像映射一样简单，但查询在Mysql工作台中工作，数据没问题，但不知道Nhibernate。 所以目前我得到了异常问题而且我知道这是错误的，但是无法弄清楚如何做到这一点，而且我不想用简单的SQL查询来做它，我很乐意去做Object Way。
感谢Stack-overflow社区。
答案 0 :(得分：0)
JoinAlias方法最常用的重载有2个参数：导航属性的表达式和别名的表达式。
您不需要指定＆＃34; on＆＃34; condition - NHibernate将使用映射解决它。
为此，您必须为UserFrom，UserTo，GatewayTable添加导航属性。您可以保留旧属性，但将其重命名为UserFromId并将类型更改为int（并检查其他属性的类型：我猜Amount不应该是string，而是{{ 1}}，decimal或double）。
如果您不想或不想添加导航属性，那么您将不得不使用子查询，因为据我所知，如果没有映射导航属性，就无法在NHibernate中执行连接。
int另外我建议你创建一个自定义Dto模型并使用ResultTransformer而不是只返回元组：
var results = session.QueryOver<TransactionTable>(() => transactionAlias)
.Left.JoinAlias(pr => pr.UserFrom, () => usersFromAlias)
.Left.JoinAlias(pr => pr.UserTo, () => usersToAlias)
.Left.JoinAlias(pr => pr.GatewayTable, () => gatewayAlias)
.SelectList(list => list
.Select(pr => pr.TransactionId)
.Select(pr => pr.Amount)
.Select(pr => pr.Reason)
.Select(pr => pr.TransactionDatetime)
.Select(pr => pr.GatewayTableId)
.Select(Projections.Conditional(
Restrictions.Eq(
Projections.Property(() => transactionAlias.UserFromId), 0),
Projections.Constant("Paypal"),
Projections.Property(() => usersFromAlias.FullName)
))
.Select(Projections.Conditional(
Restrictions.Eq(
Projections.Property(() => transactionAlias.UserToId), 0),
Projections.Constant("Paypal"),
Projections.Property(() => usersToAlias.FullName)
)))
.List<object[]>();
答案 1 :(得分：0)
我们需要的是关系映射。这由many-to-one和one-to-many表示。文档
所以，例如这个
<property name="UserFrom" column="user_from" type="String"></property>
应该是
<many-to-one name="UserFrom" column="user_from_id" class="User" />
<property name="UserFromId" column="user_from_id" type="Int32"
insert="false" update="false" />
我们引用此类用户的实体应具有属性
public virtual User UserFrom { get; set; }
public virtual int UserFromId { get; set; }
第二个不需要..但有时可能有用。
检查这些：