【发布时间】：2014-09-23 05:06:22
【问题描述】：
我想从 Google App Engine 数据存储中获取除一个特定类别之外的类别数据。
为此，我的 ApiMethod 中的查询如下所示：
Query query = mgr
.createQuery("Select c from IconCategoryMaster c where c.categoryIsPurchased = :isPurchased and c.categoryName != :catName order by c.categoryName,c.categoryType desc");
query.setParameter("isPurchased", true);
query.setParameter("catName", "TemplateICons");
当我尝试执行此 API 时，我收到如下异常：
com.google.api.server.spi.SystemService invokeServiceMethod: Portion of expression could not be parsed: != :catName
Portion of expression could not be parsed: != :catName
org.datanucleus.store.query.QueryCompilerSyntaxException: Portion of expression could not be parsed: != :catName
at org.datanucleus.query.compiler.JPQLParser.parse(JPQLParser.java:77)
at org.datanucleus.query.compiler.JavaQueryCompiler.compileFilter(JavaQueryCompiler.java:466)
at org.datanucleus.query.compiler.JPQLCompiler.compile(JPQLCompiler.java:81)
at org.datanucleus.store.query.AbstractJPQLQuery.compileInternal(AbstractJPQLQuery.java:271)
at org.datanucleus.store.query.Query.setImplicitParameter(Query.java:799)
at org.datanucleus.api.jpa.JPAQuery.setParameter(JPAQuery.java:437)
at org.datanucleus.api.jpa.JPAQuery.setParameter(JPAQuery.java:57)
at com.wallpapermaker.keepcalm.IconMasterEndpoint.getAllIcons(IconMasterEndpoint.java:228)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:45)
at com.google.api.server.spi.SystemService.invokeServiceMethod(SystemService.java:359)
at com.google.api.server.spi.SystemServiceServlet.execute(SystemServiceServlet.java:160)
at com.google.api.server.spi.SystemServiceServlet.doPost(SystemServiceServlet.java:118)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:438)
at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:445)
at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:220)
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:309)
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:301)
at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:442)
at java.lang.Thread.run(Thread.java:724)
谁能帮助我解决为什么我会遇到这种异常以及我哪里出错了？ 谢谢。
【问题讨论】：
标签： android google-app-engine jpa google-cloud-datastore