無法分解 Spark 資料框中的巢狀 JSON

問題內容

我是 spark 新手。我試圖展平數據框，但未能透過「爆炸」做到這一點。

原始資料框架構如下：

id|approvaljson
1|[{"approvertype":"1st line manager","status":"approved"},{"approvertype":"2nd line manager","status":"approved"}]
2|[{"approvertype":"1st line manager","status":"approved"},{"approvertype":"2nd line manager","status":"rejected"}]

我需要將其轉換為以下架構？

id|approvaltype|status
1|1st line manager|approved
1|2nd line manager|approved
2|1st line manager|approved
2|2nd line manager|rejected

我已經嘗試過

df_exploded = df.withcolumn("approvaljson", explode("approvaljson"))

但是我得到了錯誤：

Cannot resolve "explode(ApprovalJSON)" due to data type mismatch:
parameter 1 requires ("ARRAY" or "MAP") type, however, "ApprovalJSON"
is of "STRING" type.;

正確答案

首先將類似json 的字串解析為結構數組，然後使用inline 將數組分解為行和列

df1 = df.withcolumn("approvaljson", f.from_json("approvaljson", schema="array<struct<approvertype string, status string>>"))
df1 = df1.select("id", f.inline('approvaljson'))

結果

df1.show()

+---+----------------+--------+
| ID|    ApproverType|  Status|
+---+----------------+--------+
|  1|1st Line Manager|Approved|
|  1|2nd Line Manager|Approved|
|  2|1st Line Manager|Approved|
|  2|2nd Line Manager|Rejected|
+---+----------------+--------+

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