【发布时间】：2020-01-31 00:52:16
【问题描述】：
尝试构建管道以从第 3 方 REST API 端点数据源中读取数据。
我正在使用 Hub 中的 HTTP（1.2.0 版）插件。
响应请求网址为：https://api.example.io/v2/somedata?return_count=false
响应正文示例：
{
"paging": {
"token": "12456789",
"next": "https://api.example.io/v2/somedata?return_count=false&__paging_token=123456789"
},
"data": [
{
"cID": "aerrfaerrf",
"first": true,
"_id": "aerfaerrfaerrf",
"action": "aerrfaerrf",
"time": "1970-10-09T14:48:29+0000",
"email": "example@aol.com"
},
{...}
]
}
日志中的主要错误是：
java.lang.NullPointerException: null
at io.cdap.plugin.http.source.common.pagination.BaseHttpPaginationIterator.getNextPage(BaseHttpPaginationIterator.java:118) ~[1580429892615-0/:na]
at io.cdap.plugin.http.source.common.pagination.BaseHttpPaginationIterator.ensurePageIterable(BaseHttpPaginationIterator.java:161) ~[1580429892615-0/:na]
at io.cdap.plugin.http.source.common.pagination.BaseHttpPaginationIterator.hasNext(BaseHttpPaginationIterator.java:203) ~[1580429892615-0/:na]
at io.cdap.plugin.http.source.batch.HttpRecordReader.nextKeyValue(HttpRecordReader.java:60) ~[1580429892615-0/:na]
at io.cdap.cdap.etl.batch.preview.LimitingRecordReader.nextKeyValue(LimitingRecordReader.java:51) ~[cdap-etl-core-6.1.1.jar:na]
at org.apache.spark.rdd.NewHadoopRDD$$anon$1.hasNext(NewHadoopRDD.scala:214) ~[spark-core_2.11-2.3.3.jar:2.3.3]
at org.apache.spark.InterruptibleIterator.hasNext(InterruptibleIterator.scala:37) ~[spark-core_2.11-2.3.3.jar:2.3.3]
at scala.collection.Iterator$$anon$12.hasNext(Iterator.scala:439) ~[scala-library-2.11.8.jar:na]
at scala.collection.Iterator$$anon$12.hasNext(Iterator.scala:439) ~[scala-library-2.11.8.jar:na]
at scala.collection.Iterator$$anon$12.hasNext(Iterator.scala:439) ~[scala-library-2.11.8.jar:na]
at org.apache.spark.internal.io.SparkHadoopWriter$$anonfun$4.apply(SparkHadoopWriter.scala:128) ~[spark-core_2.11-2.3.3.jar:2.3.3]
at org.apache.spark.internal.io.SparkHadoopWriter$$anonfun$4.apply(SparkHadoopWriter.scala:127) ~[spark-core_2.11-2.3.3.jar:2.3.3]
at org.apache.spark.util.Utils$.tryWithSafeFinallyAndFailureCallbacks(Utils.scala:1415) ~[spark-core_2.11-2.3.3.jar:2.3.3]
at org.apache.spark.internal.io.SparkHadoopWriter$.org$apache$spark$internal$io$SparkHadoopWriter$$executeTask(SparkHadoopWriter.scala:139) [spark-core_2.11-2.3.3.jar:2.3.3]
at org.apache.spark.internal.io.SparkHadoopWriter$$anonfun$3.apply(SparkHadoopWriter.scala:83) [spark-core_2.11-2.3.3.jar:2.3.3]
at org.apache.spark.internal.io.SparkHadoopWriter$$anonfun$3.apply(SparkHadoopWriter.scala:78) [spark-core_2.11-2.3.3.jar:2.3.3]
at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:87) [spark-core_2.11-2.3.3.jar:2.3.3]
at org.apache.spark.scheduler.Task.run(Task.scala:109) [spark-core_2.11-2.3.3.jar:2.3.3]
at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:345) [spark-core_2.11-2.3.3.jar:2.3.3]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_232]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_232]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_232]
可能的问题
在尝试解决此问题一段时间后，我认为问题可能出在
分页
- Data Fusion HTTP插件有很多处理分页的方法
- 根据上面的响应正文，分页类型的最佳选择似乎是
Link in Response Body - 对于所需的 Next Page JSON/XML Field Path 参数，我尝试了
$.paging.next和paging/next。两者都不起作用。 - 我已验证
/paging/next中的链接在 Chrome 中打开时有效
- 根据上面的响应正文，分页类型的最佳选择似乎是
认证
- 当只是尝试在 Chrome 中查看响应 URL 时，会弹出一个提示，询问用户名和密码
- 只需输入用户名的 API 密钥即可在 Chrome 中通过此提示
- 要在 Data Fusion HTTP 插件中执行此操作，API 密钥用于 基本身份验证部分中的用户名
在数据源是 REST API 的 Google Cloud Data Fusion 中，任何人都成功地创建了管道？
【问题讨论】：
标签： rest pagination endpoint google-cloud-data-fusion