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sachin_32
sachin_32
Silver ⭐️⭐️⭐️
March 1, 2022
Solved

Pick Column Based on Index Number

I have the Flow File which has Duplicate Column i want to pick the Column threw index Number,
is it possible to do with Query Record or any Processor 

Note: Column Will change with every new Flow File coming 

araujo
araujoAnswer
Platinum ⭐️⭐️⭐️
March 3, 2022

Here's the flow template for those who have older nifi versions

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9 replies

araujo
Platinum ⭐️⭐️⭐️
araujo
Platinum ⭐️⭐️⭐️
March 1, 2022

Hi, @sachin_32 ,

 

I guess this is coming as a CSV file, right?

You can achieve what you want with the following approach:

 

  • Configure your CSV Reader to ignore and skip the header line (if any)
  • Configure your CSV Read to use the following schema:

 

{
  "type": "record",
  "name": "SensorReading",
  "namespace": "com.cloudera.example",
  "doc": "This is a sample sensor reading",
  "fields": [
    { "name": "c1", "type": "string" },
    { "name": "c2", "type": "string" },
    { "name": "c3", "type": "string" }
  ]
}​

 

 

Ensure you use a schema with the exact number of columns that your input file has.

 

  • In your QueryRecord you can then refer to the columns as c1, c2, etc...:

 

select c1, c2, c3
from flowfile​

 

 

 

 

Cheers,

André

 

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sachin_32
sachin_32Author
Silver ⭐️⭐️⭐️
March 1, 2022

Thanks for your Suggestion   but in this case i don't have any Exact Number of columns it will keep changing with incoming flow file it completely depends on the Flowfile And the scenario is i have few columns which can directly pick by giving the name of column  but for some column which is coming more than one for that i need to setup like indexing  and it's around 10-15 files which has this kind of issues so can you suggest for that ?

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araujo
Platinum ⭐️⭐️⭐️
araujo
Platinum ⭐️⭐️⭐️
March 3, 2022

@Sachin 

 

Here's another attempt at this (hopefully the last one 🙂 😞

 

I created the attached example that gets a flowfile and aattribute INDEX as you described above.

It then uses an UpdateAttribute to convert the INDEX attribute into a FILTER that we can use in the QueryRecord processor.

 

The QueryRecord process uses a fixed schema that has 100 columns. It's ok if your CSV has less columns. If the CSV can have more than 100 columns you need to update the schema to the maximum of columns you expect to receive in any CSV.

 

The output is a flowfile with the exact columns that were specified in the INDEX attribute.

 

Hope this helps.

 

Cheers,

Andre

 

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sachin_32
sachin_32Author
Silver ⭐️⭐️⭐️
March 3, 2022

Thanks for the Help 🙂

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