如何在Apache NiFi中重新排序CSV列 [英] How to reorder CSV columns in Apache NiFi

问题描述

在Apache Nifi中的csv中对列进行重新排序.

Reorder column in a csv in apache nifi.

输入-我有多个文件，它们具有相同的列，但顺序不同.

Input - I have multiple files which have same columns but are in different order.

输出-刮擦一些列并以相同顺序存储.

Output - Scrape some columns and store in same order.

推荐答案

在我的情况下，因为我确定这些列将包含在所有CSV文件中，所以我只需要对其重新排序.所以我用QueryRecord重新排序我的csv文件.

In my case, because I'm sure those columns will be included in all CSV files, I just need to reorder them. So I use QueryRecord to reorder my csv files.

例如，这是我的csv文件:

For example, here're my csv files:

\\file1
name, age, location, gender
Jack, 40, TW, M
Lisa, 30, CA, F 

\\file2
name, location, gender, age
Mary, JP, F, 25
Kate, DE, F, 23

我想将列重新排序为location,name,gender,age，我在QueryRecord中设置了名为reorder_data的新属性，其值类似于:

I'd like to reorder columns to location,name,gender,age, I set a new property in QueryRecord named reorder_data, with the value like:

SELECT location,name,gender,age FROM FLOWFILE

然后，流文件中的数据将变为:

Then data in the flowfile will become:

\\file1 - reordered
location, name, gender, age
TW, Jack, M, 40
CA, Lisa, F, 30

\\file2 - reordered
location, name, gender, age
JP, Mary, F, 25
DE, Kate, F, 23

因此，我可以从QueryRecord输出重新排序的数据以及原始数据，这非常方便.

Thus, I can get reordered data output from QueryRecord as well as original data, it's very convenient.

顺便说一句，您也可以使用组变量或属性来设置列顺序以更好地维护:

BTW, You can also use group variable or attribute to set column order for better maintenance:

//Group variable or attribute
column_order   location,name,gender,age

//Property in QueryRecord
reorder_data   SELECT ${column_order} FROM FLOWFILE

这篇关于如何在Apache NiFi中重新排序CSV列的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！