I am new at dataflow, and i am trying to write some message to pub/sub when tryin to use the apply method for PubsubIO.writeStrings().to("projects/market-place-sql/topics/emisiones") and it say: [
我是dataflow的新手，我试图在pubsubIO.writeStrings（）。（“projects / market-place-sql / topics / emisiones”）中使用apply方法时向pub / sub写一些消息说：[]
1 个解决方案
#1
1
The error is simply a type mismatch. The apply() method for the Pipeline class accepts a second parameter of the type PTransform<? super PBegin,OutputT>.
错误只是类型不匹配。 Pipeline类的apply（）方法接受PTransform <？类型的第二个参数。超级PBegin，OutputT>。
PubSubIO.writeStrings().to() returns a PTransform<PCollection<T>,PDone> type. Hence, the type mismatch.
PubSubIO.writeStrings（）。to（）返回PTransform
Based on the screenshot of the error, it looks like p is a Pipeline object. You'll need to first apply an input transform to the Pipeline object, which will return a PCollection. Then call apply() on the PCollection.
根据错误的屏幕截图，看起来p是一个Pipeline对象。您需要首先将输入变换应用于Pipeline对象，该对象将返回PCollection。然后在PCollection上调用apply（）。
Example:
例：
p.apply("read from Pub/Sub", PubsubIO.readMessages().fromSubscription("subscription/path"))
.apply("write to Pub/Sub", PubsubIO.writeStrings().to("topic/path"));
p.run();
References: Pipeline.apply(), PCollection.apply()
参考文献：Pipeline.apply（），PCollection.apply（）
#1
1
The error is simply a type mismatch. The apply() method for the Pipeline class accepts a second parameter of the type PTransform<? super PBegin,OutputT>.
错误只是类型不匹配。 Pipeline类的apply（）方法接受PTransform <？类型的第二个参数。超级PBegin，OutputT>。
PubSubIO.writeStrings().to() returns a PTransform<PCollection<T>,PDone> type. Hence, the type mismatch.
PubSubIO.writeStrings（）。to（）返回PTransform
Based on the screenshot of the error, it looks like p is a Pipeline object. You'll need to first apply an input transform to the Pipeline object, which will return a PCollection. Then call apply() on the PCollection.
根据错误的屏幕截图，看起来p是一个Pipeline对象。您需要首先将输入变换应用于Pipeline对象，该对象将返回PCollection。然后在PCollection上调用apply（）。
Example:
例：
p.apply("read from Pub/Sub", PubsubIO.readMessages().fromSubscription("subscription/path"))
.apply("write to Pub/Sub", PubsubIO.writeStrings().to("topic/path"));
p.run();
References: Pipeline.apply(), PCollection.apply()
参考文献：Pipeline.apply（），PCollection.apply（）