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角度元素：在 OnInit 函数中未定义自定义元素属性

分类：编程问答

如何解决角度元素：在 OnInit 函数中未定义自定义元素属性

我们正在使用 Angular Elements 从我们的组件库中创建自定义元素（Web 组件）。然而，在执行此操作后，Angular 生命周期钩子的执行顺序似乎与通常不同。例如，ngOnChanges 通常在 ngOnInit 之前执行，但现在顺序翻转了； ngOnInit 在 ngOnChanges 之前运行，因此 ngOnInit 中的输入变量未定义。据我所知，这似乎是故意的 link here。我想知道是否有一种解决方法可以强制 ngOnInit 首先运行或暂停运行 ngOnInit 代码直到首先发生绑定？在运行 ngOnInit 内部的启动逻辑之前，我们需要确保变量具有正确的值。

注意：我们无权访问原始组件的代码，因此我们无法更改任何代码，我们只能控制父组件的使用方式。

组件代码：

java.lang.NoSuchMethodError: com.facebook.fb303.FacebookService$Client.sendBaSEOneway(Ljava/lang/String;Lorg/apache/thrift/TBase;)V
  at com.facebook.fb303.FacebookService$Client.send_shutdown(FacebookService.java:436)
  at com.facebook.fb303.FacebookService$Client.shutdown(FacebookService.java:430)
  at org.apache.hadoop.hive.metastore.HivemetastoreClient.close(HivemetastoreClient.java:619)
  at sun.reflect.GeneratedMethodAccessor18.invoke(UnkNown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:498)
  at org.apache.hadoop.hive.metastore.retryingmetastoreClient.invoke(retryingmetastoreClient.java:154)
  at com.sun.proxy.$Proxy32.close(UnkNown Source)
  at sun.reflect.GeneratedMethodAccessor18.invoke(UnkNown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:498)
  at org.apache.hadoop.hive.metastore.HivemetastoreClient$SynchronizedHandler.invoke(HivemetastoreClient.java:2562)
  at com.sun.proxy.$Proxy32.close(UnkNown Source)
  at org.apache.hadoop.hive.ql.Metadata.Hive.close(Hive.java:415)
  at org.apache.hadoop.hive.ql.Metadata.Hive.create(Hive.java:331)
  at org.apache.hadoop.hive.ql.Metadata.Hive.getInternal(Hive.java:318)
  at org.apache.hadoop.hive.ql.Metadata.Hive.get(Hive.java:294)
  at org.apache.spark.sql.hive.client.HiveClientImpl$$anonfun$withHiveState$1.apply(HiveClientImpl.scala:278)
  at org.apache.spark.sql.hive.client.HiveClientImpl.liftedTree1$1(HiveClientImpl.scala:221)
  at org.apache.spark.sql.hive.client.HiveClientImpl.retryLocked(HiveClientImpl.scala:220)
  at org.apache.spark.sql.hive.client.HiveClientImpl.withHiveState(HiveClientImpl.scala:266)
  at org.apache.spark.sql.hive.client.HiveClientImpl.databaseExists(HiveClientImpl.scala:356)
  at org.apache.spark.sql.hive.HiveExternalCatalog$$anonfun$databaseExists$1.apply$mcZ$sp(HiveExternalCatalog.scala:217)
  at org.apache.spark.sql.hive.HiveExternalCatalog$$anonfun$databaseExists$1.apply(HiveExternalCatalog.scala:217)
  at org.apache.spark.sql.hive.HiveExternalCatalog$$anonfun$databaseExists$1.apply(HiveExternalCatalog.scala:217)
  at org.apache.spark.sql.hive.HiveExternalCatalog.withClient(HiveExternalCatalog.scala:99)
  at org.apache.spark.sql.hive.HiveExternalCatalog.databaseExists(HiveExternalCatalog.scala:216)
  at org.apache.spark.sql.catalyst.catalog.ExternalCatalogWithListener.databaseExists(ExternalCatalogWithListener.scala:71)
  at org.apache.spark.sql.catalyst.catalog.SessionCatalog.databaseExists(SessionCatalog.scala:238)
  at org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveRelations$.isRunningDirectlyOnFiles(Analyzer.scala:750)
  at org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveRelations$.resolveRelation(Analyzer.scala:683)
  at org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveRelations$$anonfun$apply$8.applyOrElse(Analyzer.scala:715)
  at org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveRelations$$anonfun$apply$8.applyOrElse(Analyzer.scala:708)
  at org.apache.spark.sql.catalyst.plans.logical.AnalysisHelper$$anonfun$resolveOperatorsUp$1$$anonfun$apply$1.apply(AnalysisHelper.scala:90)
  at org.apache.spark.sql.catalyst.plans.logical.AnalysisHelper$$anonfun$resolveOperatorsUp$1$$anonfun$apply$1.apply(AnalysisHelper.scala:90)
  at org.apache.spark.sql.catalyst.trees.CurrentOrigin$.withOrigin(TreeNode.scala:70)
  at org.apache.spark.sql.catalyst.plans.logical.AnalysisHelper$$anonfun$resolveOperatorsUp$1.apply(AnalysisHelper.scala:89)
  at org.apache.spark.sql.catalyst.plans.logical.AnalysisHelper$$anonfun$resolveOperatorsUp$1.apply(AnalysisHelper.scala:86)
  at org.apache.spark.sql.catalyst.plans.logical.AnalysisHelper$.allowInvokingTransformsInAnalyzer(AnalysisHelper.scala:194)
  at org.apache.spark.sql.catalyst.plans.logical.AnalysisHelper$class.resolveOperatorsUp(AnalysisHelper.scala:86)
  at org.apache.spark.sql.catalyst.plans.logical.LogicalPlan.resolveOperatorsUp(LogicalPlan.scala:29)
  at org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveRelations$.apply(Analyzer.scala:708)
  at org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveRelations$.apply(Analyzer.scala:654)
  at org.apache.spark.sql.catalyst.rules.RuleExecutor$$anonfun$execute$1$$anonfun$apply$1.apply(RuleExecutor.scala:87)
  at org.apache.spark.sql.catalyst.rules.RuleExecutor$$anonfun$execute$1$$anonfun$apply$1.apply(RuleExecutor.scala:84)
  at scala.collection.LinearSeqOptimized$class.foldLeft(LinearSeqOptimized.scala:124)
  at scala.collection.immutable.List.foldLeft(List.scala:84)
  at org.apache.spark.sql.catalyst.rules.RuleExecutor$$anonfun$execute$1.apply(RuleExecutor.scala:84)
  at org.apache.spark.sql.catalyst.rules.RuleExecutor$$anonfun$execute$1.apply(RuleExecutor.scala:76)
  at scala.collection.immutable.List.foreach(List.scala:392)
  at org.apache.spark.sql.catalyst.rules.RuleExecutor.execute(RuleExecutor.scala:76)
  at org.apache.spark.sql.catalyst.analysis.Analyzer.org$apache$spark$sql$catalyst$analysis$Analyzer$$executeSameContext(Analyzer.scala:127)
  at org.apache.spark.sql.catalyst.analysis.Analyzer.execute(Analyzer.scala:121)
  at org.apache.spark.sql.catalyst.analysis.Analyzer$$anonfun$executeAndCheck$1.apply(Analyzer.scala:106)
  at org.apache.spark.sql.catalyst.analysis.Analyzer$$anonfun$executeAndCheck$1.apply(Analyzer.scala:105)
  at org.apache.spark.sql.catalyst.plans.logical.AnalysisHelper$.markInAnalyzer(AnalysisHelper.scala:201)
  at org.apache.spark.sql.catalyst.analysis.Analyzer.executeAndCheck(Analyzer.scala:105)
  at org.apache.spark.sql.execution.QueryExecution.analyzed$lzycompute(QueryExecution.scala:57)
  at org.apache.spark.sql.execution.QueryExecution.analyzed(QueryExecution.scala:55)
  at org.apache.spark.sql.execution.QueryExecution.assertAnalyzed(QueryExecution.scala:47)
  at org.apache.spark.sql.Dataset$.ofRows(Dataset.scala:78)
  at org.apache.spark.sql.SparkSession.table(SparkSession.scala:637)
  at org.apache.spark.sql.SparkSession.table(SparkSession.scala:633)

家长使用：

export class CustomButton implements OnInit,OnChanges {

@input() title: any;

constructor(public userService: UserService) { }

ngOnInit() {
    console.log(this.title);  // <--- Executes first,variable undefined
    // ... Initiation Logic ... // This logic is failing due to undefined
}

ngOnChanges(simpleChanges: SimpleChanges) {
    console.log(simpleChanges);     // <--- Executes second,variable has proper values
}
}

感谢您的帮助：]

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