嵌入式实体的自动ID [英] Automatic ID for embedded entity

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本文介绍了嵌入式实体的自动ID的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

有没有办法让数据存储为嵌入式实体分配一个自动ID?我使用 Mutation.Builder.addInsertAutoId ,它适用于普通实体,但在尝试为嵌入式实体生成ID时遇到错误:


$ b


ApplicationError:1:实体缺少密钥。

示例代码

  Entity.Builder entity = Entity.newBuilder(); 
Key.Builder key = makeKey(m.getClass()。getSimpleName());
entity.setKey(key);
entity.addProperty(makeProperty(name,makeValue(m.getName())));

Entity.Builder embeddedEntity = Entity.newBuilder();
addProperty(embeddedEntity,name,一个不同的名字);

entity.addProperty(makeProperty(embedded,makeValue(embeddedEntity).setIndexed(false)));

CommitRequest req = CommitRequest.newBuilder()
.setMode(CommitRequest.Mode.NON_TRANSACTIONAL)
.setMutation(
Mutation.newBuilder()
。 addInsertAutoId(entity)
.addInsertAutoId(embeddedEntity)

.build();

堆栈跟踪

 
com.google.apphosting.api.ApiProxy $ ApplicationException:ApplicationError:1:实体缺少密钥。
at com.google.appengine.api.datastore.dev.LocalDatastoreV4Service.commit(LocalDatastoreV4Service.java:162)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun。 reflection.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java: 498)
at com.google.appengine.tools.development.ApiProxyLocalImpl $ AsyncApiCall.callInternal(ApiProxyLocalImpl.java:521)
at com.google.appengine.tools.development.ApiProxyLocalImpl $ AsyncApiCall.call( ApiProxyLocalImpl.java:475)
在com.google.appengine.tools.development.ApiProxyLocalImpl $ AsyncApiCall.call(ApiProxyLocalImpl.java:452)
在java.util.concurrent.Executors $ PrivilegedCallable $ 1.run (Executors.java:533)$ java.util.AccessController.doPrivileged(本地方法)
$ java.util.concurrent.Executors $ b $ $ $ Privileg $ java.util.concurrent.FutureTask.run(FutureTask.java:266)
在java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:
at java.util.concurrent.ThreadPoolExecutor $ Worker.run(ThreadPoolExecutor.java:617)$ b $ at java.lang.Thread.run(Thread.java:745)
pre>

我尝试了不同的变体,并且在什么时候调用 addInsertAutoId

$并不重要。 b $ b

解决方案

设置'存根'键,如 App Engine的例子,诀窍:

  Entity.Builder embeddedEntity = Entity.newBuilder(); 
addProperty(embeddedEntity,name,一个不同的名字);
embeddedEntity.setKey(entity.getKey)//←必需


Is there a way to let the datastore assign an automatic ID for an embedded entity? I use Mutation.Builder.addInsertAutoId and it works on "normal" entities, but I get an error when trying to generate an ID for an embedded entity:

ApplicationError: 1: Entity is missing key.

Example code

Entity.Builder entity = Entity.newBuilder();
Key.Builder key = makeKey(m.getClass().getSimpleName());
entity.setKey(key);
entity.addProperty(makeProperty("name", makeValue(m.getName())));

Entity.Builder embeddedEntity = Entity.newBuilder();
addProperty(embeddedEntity, "name", "a different name");

entity.addProperty(makeProperty("embedded", makeValue(embeddedEntity).setIndexed(false)));

CommitRequest req = CommitRequest.newBuilder()
        .setMode(CommitRequest.Mode.NON_TRANSACTIONAL)
        .setMutation(
                Mutation.newBuilder()
                        .addInsertAutoId(entity)
                        .addInsertAutoId(embeddedEntity)
        )
        .build();

The stack trace

com.google.apphosting.api.ApiProxy$ApplicationException: ApplicationError: 1: Entity is missing key.
    at com.google.appengine.api.datastore.dev.LocalDatastoreV4Service.commit(LocalDatastoreV4Service.java:162)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.google.appengine.tools.development.ApiProxyLocalImpl$AsyncApiCall.callInternal(ApiProxyLocalImpl.java:521)
    at com.google.appengine.tools.development.ApiProxyLocalImpl$AsyncApiCall.call(ApiProxyLocalImpl.java:475)
    at com.google.appengine.tools.development.ApiProxyLocalImpl$AsyncApiCall.call(ApiProxyLocalImpl.java:452)
    at java.util.concurrent.Executors$PrivilegedCallable$1.run(Executors.java:533)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.util.concurrent.Executors$PrivilegedCallable.call(Executors.java:530)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

I tried different variations and it does not matter at what point I call addInsertAutoId.

解决方案

Setting a 'stub' key, as shown in the examples for App Engine, does the trick:

Entity.Builder embeddedEntity = Entity.newBuilder();
addProperty(embeddedEntity, "name", "a different name");
embeddedEntity.setKey(entity.getKey)                      // ← required

这篇关于嵌入式实体的自动ID的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!

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