null - WSO2DSS 如何管理包含一些空值列的查询的 XML 映射

Question

我有一个简单的查询

select t.firstname, t.lastname, t.zipcode, t.city 
from name_data t where name_id = ?

这 '？' 是输入参数，永远不会为空。

该查询返回一条类似于以下内容之一的记录：

案例 1 - 个人

 'First Name'   'Last Name'     'zipcode'   'city'
 -------------------------------------------------------
 John           Doe             1177        Somewhere

案例 2 - 公司

 'First Name'   'Last Name'     'zipcode'   'city'
 -----------------------------------------------------------
 <<null>>       ACME Ltd        1199        'Somewhere else'

当我获得第二条记录时，DSS 会抛出 NullPointerException。

我猜这是因为 Firstname 中的 <> 值，我找到了一种通过测试 SQL (Oracle) 中的空值来绕过它的方法

“选择 nvl(t.firstname, ' ') firstname, nvl(t.lastname, ' '), lastname, nvl(t.zipcode, ' '), nvl(t.city, ' ') 等...”

这适用于所有可以为空的列（我的查询比这长一点），因为它们是可选的。

我知道如果数据库设计正确（例如创建两个不同的实体来管理人员和公司），这不应该发生（理论上），但它是一个商业产品，然后我无法更改它，我用一个简单的案例来解释一个很长的查询。

我的 .dbs 的摘录是：

<?xml version="1.0" encoding="UTF-8"?>
<data xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:noNamespaceSchemaLocation="http:///org/wso2/carbonstudio/eclipse/ds" 
    name="${groupId}.${artifactId}-customeraddress-1" 
    serviceNamespace="urn:customeraddress.database.mycompany.org/1" 
    serviceGroup="${groupId}" baseURI="">
  <description>This is the datasource to access the customer address information</description>
  <config id="ambocs">
    <property name="org.wso2.ws.dataservice.driver">@ambocs.driver@</property>
    <property name="org.wso2.ws.dataservice.protocol">@ambocs.url@</property>
    <property name="org.wso2.ws.dataservice.user">@ambocs.user@</property>
    <property name="org.wso2.ws.dataservice.password">@ambocs.password@</property>
    <property name="org.wso2.ws.dataservice.minpoolsize">@ambocs.minpoolsize@</property>
    <property name="org.wso2.ws.dataservice.maxpoolsize">@ambocs.maxpoolsize@</property>
    <property name="org.wso2.ws.dataservice.validation_query">select 1 from dual</property>
  </config>
  <query id="getCustomerAddressByIdRef" useConfig="ambocs" returnRowId="true">
    <sql>
        select 
            nvl(nd.first_name, ' ') first_name, 
            nvl(nd.last_name, ' ') last_name,
            nvl(nd.adr_zip, ' ') zipcode,
            nvl(nd.adr_city, ' ') city, 
            nvl(nd.adr_country, ' ') country 
        from name_data nd
        where nd.name_id = ?
    </sql>
    <properties>
      <property name="org.wso2.ws.dataservice.query_timeout"></property>
      <property name="org.wso2.ws.dataservice.fetch_direction"></property>
      <property name="org.wso2.ws.dataservice.fetch_size"></property>
      <property name="org.wso2.ws.dataservice.max_field_size"></property>
      <property name="org.wso2.ws.dataservice.max_rows"></property>
    </properties>
    <result element="ContactDetails" rowName="ContactDetail" 
       defaultNamespace="urn:customeraddress.database.mycompany.org/1" outputType="xml">
      <attribute name="firstName" column="first_name" query-param="" requiredRoles="" xsdType="xs:string"/>
      <attribute name="lastName" column="last_business_name" query-param="" requiredRoles="" xsdType="xs:string"/>
      <attribute name="locality" column="city" query-param="" requiredRoles="" xsdType="xs:string"/>
      <attribute name="postcode" column="zipcode" query-param="" requiredRoles="" xsdType="xs:string"/>
      <attribute name="country" column="country" query-param="" requiredRoles="" xsdType="xs:string"/>      
    </result>
    <param name="nameId" type="IN" sqlType="STRING" defaultValue="" />
  </query>
  <operation name="getCustomerAddressById">
    <call-query href="getCustomerAddressByIdRef">
        <with-param name="nameId" column="nameId" query-param="nameId"/>
    </call-query>
  </operation>
</data>

您是否知道是否可以选择放入 .dbs 以管理查询返回的空值？

我试图在 wso2.org 上找到一个文档，但它是非常简单的示例，与此案例无关。

更新这里的表模式：

CREATE TABLE "NAME_DATA"
(
    "NAME_ID"               NUMBER(9,0) CONSTRAINT "PK_NAME_ID" NOT NULL ENABLE,
    "SYS_CREATION_DATE"     DATE NOT NULL ENABLE,
    "SYS_UPDATE_DATE"       DATE,
    "LAST_NAME"             VARCHAR2(60),
    "FIRST_NAME"            VARCHAR2(32),
    "ZIP_CODE"              VARCHAR2(4),
    "CITY"                  VARCHAR2(255),
    "COUNTRY"               CHAR(3 BYTE),
    CONSTRAINT "NAME_DATA_PK" PRIMARY KEY ("NAME_ID")
) 

CREATE UNIQUE INDEX "NAME_DATA_PK" ON "NAME_DATA" ("NAME_ID")
CREATE INDEX "IDX_NAME_DATA_1" ON "NAME_DATA"("LAST_NAME","FIRST_NAME")
CREATE INDEX "IDX_NAME_DATA_2" ON "NAME_DATA"(UPPER("FIRST_NAME"))
CREATE INDEX "IDX_NAME_DATA_3" ON "NAME_DATA"(UPPER("LAST_NAME"))

更新 2 - 堆栈跟踪：

TID: [0] [WSO2 Data Services Server] [2012-03-27 14:02:22,730] ERROR {org.apache.axis2.transport.http.AxisServlet} -   {org.apache.axis2.transport.http.AxisServlet}
java.lang.NullPointerException
    at com.ctc.wstx.sw.BaseNsStreamWriter.doWriteAttr(BaseNsStreamWriter.java:468)
    at com.ctc.wstx.sw.BaseNsStreamWriter.writeAttribute(BaseNsStreamWriter.java:230)
    at org.apache.axiom.util.stax.wrapper.XMLStreamWriterWrapper.writeAttribute(XMLStreamWriterWrapper.java:88)
    at org.apache.axiom.om.impl.MTOMXMLStreamWriter.writeAttribute(MTOMXMLStreamWriter.java:230)
    at org.wso2.carbon.dataservices.core.engine.DSWrappedXMLStreamWriter.writeXMLEvent(DSWrappedXMLStreamWriter.java:418)
    at org.wso2.carbon.dataservices.core.engine.DSWrappedXMLStreamWriter.writeOutInitialXMLEvents(DSWrappedXMLStreamWriter.java:508)
    at org.wso2.carbon.dataservices.core.engine.DSWrappedXMLStreamWriter.finalizeBuffering(DSWrappedXMLStreamWriter.java:501)
    at org.wso2.carbon.dataservices.core.engine.DSWrappedXMLStreamWriter.flush(DSWrappedXMLStreamWriter.java:145)
    at org.wso2.carbon.dataservices.core.engine.DSOMDataSource.execute(DSOMDataSource.java:102)
    at org.wso2.carbon.dataservices.core.engine.DSOMDataSource.serialize(DSOMDataSource.java:110)
    at org.apache.axiom.om.impl.llom.OMSourcedElementImpl.internalSerialize(OMSourcedElementImpl.java:691)
    at org.apache.axiom.om.impl.util.OMSerializerUtil.serializeChildren(OMSerializerUtil.java:563)
    at org.apache.axiom.om.impl.llom.OMElementImpl.internalSerialize(OMElementImpl.java:875)
    at org.apache.axiom.soap.impl.llom.SOAPEnvelopeImpl.serializeInternally(SOAPEnvelopeImpl.java:283)
    at org.apache.axiom.soap.impl.llom.SOAPEnvelopeImpl.internalSerialize(SOAPEnvelopeImpl.java:245)
    at org.apache.axiom.om.impl.llom.OMSerializableImpl.serializeAndConsume(OMSerializableImpl.java:193)
    at org.apache.axis2.transport.http.SOAPMessageFormatter.writeTo(SOAPMessageFormatter.java:74)
    at org.apache.axis2.transport.http.CommonsHTTPTransportSender.sendUsingOutputStream(CommonsHTTPTransportSender.java:409)
    at org.apache.axis2.transport.http.CommonsHTTPTransportSender.invoke(CommonsHTTPTransportSender.java:286)
    at org.apache.axis2.engine.AxisEngine.send(AxisEngine.java:443)
    at org.apache.axis2.receivers.AbstractInOutSyncMessageReceiver.invokeBusinessLogic(AbstractInOutSyncMessageReceiver.java:45)
    at org.apache.axis2.receivers.AbstractMessageReceiver.receive(AbstractMessageReceiver.java:110)
    at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:181)
    at org.apache.axis2.transport.http.HTTPTransportUtils.processHTTPPostRequest(HTTPTransportUtils.java:172)
    at org.apache.axis2.transport.http.AxisServlet.doPost(AxisServlet.java:146)
    at org.wso2.carbon.core.transports.CarbonServlet.doPost(CarbonServlet.java:199)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.eclipse.equinox.http.servlet.internal.ServletRegistration.handleRequest(ServletRegistration.java:90)
    at org.eclipse.equinox.http.servlet.internal.ProxyServlet.processAlias(ProxyServlet.java:111)
    at org.eclipse.equinox.http.servlet.internal.ProxyServlet.service(ProxyServlet.java:67)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.wso2.carbon.bridge.BridgeServlet.service(BridgeServlet.java:164)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    at org.wso2.carbon.server.CarbonStuckThreadDetectionValve.invoke(CarbonStuckThreadDetectionValve.java:154)
    at org.wso2.carbon.server.TomcatServer$1.invoke(TomcatServer.java:254)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:563)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:399)
    at org.apache.coyote.http11.Http11NioProcessor.process(Http11NioProcessor.java:396)
    at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:356)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1534)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:662)
TID: [0] [WSO2 Data Services Server] [2012-03-27 14:02:22,730] ERROR {org.apache.axis2.transport.http.AxisServlet} -   {org.apache.axis2.transport.http.AxisServlet}
java.lang.NullPointerException
    at com.ctc.wstx.sw.BaseNsStreamWriter.doWriteAttr(BaseNsStreamWriter.java:468)
    at com.ctc.wstx.sw.BaseNsStreamWriter.writeAttribute(BaseNsStreamWriter.java:230)
    at org.apache.axiom.util.stax.wrapper.XMLStreamWriterWrapper.writeAttribute(XMLStreamWriterWrapper.java:88)
    at org.apache.axiom.om.impl.MTOMXMLStreamWriter.writeAttribute(MTOMXMLStreamWriter.java:230)
    at org.wso2.carbon.dataservices.core.engine.DSWrappedXMLStreamWriter.writeXMLEvent(DSWrappedXMLStreamWriter.java:418)
    at org.wso2.carbon.dataservices.core.engine.DSWrappedXMLStreamWriter.writeOutInitialXMLEvents(DSWrappedXMLStreamWriter.java:508)
    at org.wso2.carbon.dataservices.core.engine.DSWrappedXMLStreamWriter.finalizeBuffering(DSWrappedXMLStreamWriter.java:501)
    at org.wso2.carbon.dataservices.core.engine.DSWrappedXMLStreamWriter.flush(DSWrappedXMLStreamWriter.java:145)
    at org.wso2.carbon.dataservices.core.engine.DSOMDataSource.execute(DSOMDataSource.java:102)
    at org.wso2.carbon.dataservices.core.engine.DSOMDataSource.serialize(DSOMDataSource.java:110)
    at org.apache.axiom.om.impl.llom.OMSourcedElementImpl.internalSerialize(OMSourcedElementImpl.java:691)
    at org.apache.axiom.om.impl.util.OMSerializerUtil.serializeChildren(OMSerializerUtil.java:563)
    at org.apache.axiom.om.impl.llom.OMElementImpl.internalSerialize(OMElementImpl.java:875)
    at org.apache.axiom.soap.impl.llom.SOAPEnvelopeImpl.serializeInternally(SOAPEnvelopeImpl.java:283)
    at org.apache.axiom.soap.impl.llom.SOAPEnvelopeImpl.internalSerialize(SOAPEnvelopeImpl.java:245)
    at org.apache.axiom.om.impl.llom.OMSerializableImpl.serializeAndConsume(OMSerializableImpl.java:193)
    at org.apache.axis2.transport.http.SOAPMessageFormatter.writeTo(SOAPMessageFormatter.java:74)
    at org.apache.axis2.transport.http.CommonsHTTPTransportSender.sendUsingOutputStream(CommonsHTTPTransportSender.java:409)
    at org.apache.axis2.transport.http.CommonsHTTPTransportSender.invoke(CommonsHTTPTransportSender.java:286)
    at org.apache.axis2.engine.AxisEngine.send(AxisEngine.java:443)
    at org.apache.axis2.receivers.AbstractInOutSyncMessageReceiver.invokeBusinessLogic(AbstractInOutSyncMessageReceiver.java:45)
    at org.apache.axis2.receivers.AbstractMessageReceiver.receive(AbstractMessageReceiver.java:110)
    at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:181)
    at org.apache.axis2.transport.http.HTTPTransportUtils.processHTTPPostRequest(HTTPTransportUtils.java:172)
    at org.apache.axis2.transport.http.AxisServlet.doPost(AxisServlet.java:146)
    at org.wso2.carbon.core.transports.CarbonServlet.doPost(CarbonServlet.java:199)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.eclipse.equinox.http.servlet.internal.ServletRegistration.handleRequest(ServletRegistration.java:90)
    at org.eclipse.equinox.http.servlet.internal.ProxyServlet.processAlias(ProxyServlet.java:111)
    at org.eclipse.equinox.http.servlet.internal.ProxyServlet.service(ProxyServlet.java:67)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.wso2.carbon.bridge.BridgeServlet.service(BridgeServlet.java:164)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    at org.wso2.carbon.server.CarbonStuckThreadDetectionValve.invoke(CarbonStuckThreadDetectionValve.java:154)
    at org.wso2.carbon.server.TomcatServer$1.invoke(TomcatServer.java:254)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:563)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:399)
    at org.apache.coyote.http11.Http11NioProcessor.process(Http11NioProcessor.java:396)
    at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:356)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1534)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:662)

为了对此进行测试，您必须删除 DBS 中的所有“nvl(...)”，否则它运行良好。这是 first_name 为“null”的记录。

score 2 · Accepted Answer

当您在结果集中使用“属性”类型的输出映射时，会出现此问题。这是为它创建的 Jira。

作为一种解决方法，您可以将列用作元素而不是属性，它可以正确处理空值。

即在上面提供的dbs 文件中，使用结果集如下。

<result element="ContactDetails" rowName="ContactDetail" 
   defaultNamespace="urn:customeraddress.database.mycompany.org/1" outputType="xml">
  <element name="firstName" column="first_name" query-param="" requiredRoles="" xsdType="xs:string"/>
  <element name="lastName" column="last_business_name" query-param="" requiredRoles="" xsdType="xs:string"/>
  <element name="locality" column="city" query-param="" requiredRoles="" xsdType="xs:string"/>
  <element name="postcode" column="zipcode" query-param="" requiredRoles="" xsdType="xs:string"/>
  <element name="country" column="country" query-param="" requiredRoles="" xsdType="xs:string"/>      
</result>

score 0 · Accepted Answer

您能否提及您正在使用的数据服务版本？这在最新包 (wso2dataservices-2.6.3) 中运行良好。如果您在数据库表中有“空”值，那么它会在您通过 dss 检索的结果中显示为“xsi:nil="true"”。

以下结果向您展示了一个示例，其中最后一个结果集在表中包含空值。

<Entries xmlns="http://ws.wso2.org/dataservice">
   <Entry>
      <EMPLOYEENUMBER>1</EMPLOYEENUMBER>
      <LASTNAME>dinusha</LASTNAME>
   </Entry>
   <Entry>
      <EMPLOYEENUMBER **xsi:nil="true"** xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"/>
      <LASTNAME **xsi:nil="true**" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"/>
   </Entry>
</Entries>

null - WSO2DSS 如何管理包含一些空值列的查询的 XML 映射

2 回答 2

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