如何通过转换为RDD在Spark Dataset中保存嵌套或JSON对象? [英] How to save nested or JSON object in spark Dataset with converting to RDD?
本文介绍了如何通过转换为RDD在Spark Dataset中保存嵌套或JSON对象?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
我正在处理Spark代码,其中我必须将多个列值保存为对象格式并将结果保存到mongodb
I am working on the spark code where I have to save multiple column values as a object format and save the result to mongodb
给出数据集
|---|-----|------|----------|
|A |A_SRC|Past_A|Past_A_SRC|
|---|-----|------|----------|
|a1 | s1 | a2 | s2 |
我尝试过的
val ds1 = Seq(("1", "2", "3","4")).toDF("a", "src", "p_a","p_src")
val recordCol = functions.to_json(Seq($"a", $"src", $"p_a",$"p_src"),struct("a", "src", "p_a","p_src")) as "A"
ds1.select(recordCol).show(truncate = false)
给我类似的结果
+-----------------------------------------+
|A |
+-----------------------------------------+
|{"a":"1","src":"2","p_a":"3","p_src":"4"}|
+-----------------------------------------+
我期待类似
+-----------------------------------------+
|A |
+-----------------------------------------+
|{"source":"1","value":"2","p_source":"4","p_value":"3"}|
+-----------------------------------------+
如何更改除列名之外的对象类型的键.在Java中使用地图?
How can I change the keys in the object type other than column names. using maps in java ?
推荐答案
您可以在 struct
列中传递 as
,这样该名称将保存为您的名字通过.
You can pass as
in the column struct
, so that that will be saved as the name you passed.
Dataset<Row> tstDS = spark.read().format("csv").option("header", "true").load("/home/exa9/Documents/SparkLogs/y.csv");
tstDS.show();
/****
+---+-----+------+----------+
| A|A_SRC|Past_A|Past_A_SRC|
+---+-----+------+----------+
| a1| s1| a2| s2|
+---+-----+------+----------+
****/
tstDS.withColumn("A",
functions.to_json(
functions.struct(
functions.col("A").as("source"),
functions.col("A_SRC").as("value"),
functions.col("Past_A").as("p_source"),
functions.col("Past_A_SRC").as("p_value")
))
)
.select("A")
.show(false);
/****
+-----------------------------------------------------------+
|A |
+-----------------------------------------------------------+
|{"source":"a1","value":"s1","p_source":"a2","p_value":"s2"}|
+-----------------------------------------------------------+
****/
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