KSQLDB Rest API：以 json 格式返回查询结果答案

【问题标题】：KSQLDB Rest API: return query results as jsonKSQLDB Rest API：以 json 格式返回查询结果
【发布时间】：2021-03-01 02:10:35
【问题描述】：

我发出以下请求：

curl --http2 -X "POST" "http://localhost:8088/query-stream"
             -H "Content-Type: application/vnd.ksql.v1+json; charset=utf-8"
             -d $'{
                  "sql": "SELECT * FROM USERS EMIT CHANGES;",
                  "streamsProperties": {
                    "ksql.streams.auto.offset.reset": "earliest"
                  }
}

我得到的结果是：

{"queryId":"cdfb3ccc-0ab5-4186-a249-b279bfc09587","columnNames":["USERID","NAME"],"columnTypes":["STRING","STRING"]}
["1","Max"]
["2","Alex"]
["13","Andrew"]
...

有没有办法获取json格式的数据？

{"userid":"1","name":"Max"}
{"userid":"2","name":"Alex"}
{"userid":"13","name":"Andrew"}

如果这些数据是 json 格式，则将这些数据反序列化为 POCO 对象比解析“行”格式更容易。

【问题讨论】：

标签： apache-kafka ksqldb

【解决方案1】：

根据the docs，您可以设置Accept 标头。默认为application/vnd.ksqlapi.delimited.v1，但也可以设置为application/json：

curl --show-error --silent \
         -H "application/vnd.ksqlapi.delimited.v1" \
         --http2 'http://localhost:8088/query-stream' \
         --data-raw '{"sql":"SELECT * FROM CUSTOMERS WHERE ID=42;"}'
{"queryId":null,"columnNames":["ID","FIRST_NAME","LAST_NAME","EMAIL","GENDER","COMMENTS"],"columnTypes":["INTEGER","STRING","STRING","STRING","STRING","STRING"]}
[42,"Rick","Astley","r.astley@example.com","Male",""]

curl --show-error --silent \
         -H "Accept:application/json" \
         --http2 'http://localhost:8088/query-stream' \
         --data-raw '{"sql":"SELECT * FROM CUSTOMERS WHERE ID=42;"}'
[{"queryId":null,"columnNames":["ID","FIRST_NAME","LAST_NAME","EMAIL","GENDER","COMMENTS"],"columnTypes":["INTEGER","STRING","STRING","STRING","STRING","STRING"]},[42,"Rick","Astley","r.astley@example.com","Male",""]]

【讨论】：

谢谢，罗宾，但这并不是我想要的。我需要一个推送 KSQL Rest API 查询，它将我的记录作为 JSON 对象返回，而不是类似 CSV 的样式。按照您的示例，尽管您进行了拉式查询（返回单个结果），但我想以以下格式获取每条记录： { "id": 42, "first_name:"Rick", "last_name:":"Astley" , "email": "r.astley@example.com", "gender": "Male", "cmets": "" } 另一点是当我使用 -H 发出推送查询（使用 'EMIT CHANGES'）时'Accept:application/json' - 我没有得到任何结果。
我明白了 - 是的，这不是目前可用的。随时在github.com/confluentinc/ksql/issues/3526 上发表评论/投票。