topic Re: How to update prev row after comparing with current and prev row? in Talend Studio

How to update prev row after comparing with current and prev row?

dattasud — Sat, 16 Nov 2024 03:05:13 GMT

Hi All,

I am new to TOS for data processing. My previous approach was with tUniqRow but changed it using tMemorizeRow and tJavaFlex.

I am using tMemorizeRows and tJavaFlex for my duplicate row check.

Using tMemorizeRows with 2 row count, I am checking 2 row at a time. Based on my one condition, I need to update one column in the prev row.

So, in tJavaFlex based on my memorizerow data, I am able to compare and update a column for my current row in context. But to update a column value for my previous row (matched row by condition using memorizerow), how can I do that? How can I get previous row to update any column with new value.

I tried with tJavaFlex_2/tJavaRow after my tJavaFlex_1 but it executes one row at a time. So, I am not able to get previous row. Is there anyway, I can search the whole result row object(tJavaFlex_1) and set value? Can I use tMap to solve the problem? Thanks in advance.

Re: How to update prev row after comparing with current and prev row?

Anonymous — Wed, 04 Mar 2020 19:56:39 GMT

It's probably best that use the tHashInput and tHashOutput components for this.

https://help.talend.com/reader/8_lXEInq2ehdXds6XE9PsA/OxFrHZZyW9fvSE5SUBJOKQ

https://help.talend.com/reader/8_lXEInq2ehdXds6XE9PsA/kQWU35YXytKECckZ5EqvGg

Read the data into a tHashOutput for each row (uniques/non-uniques), then use the tHashInput components to read that data in again and join using a tMap.

Re: How to update prev row after comparing with current and prev row?

dattasud — Wed, 04 Mar 2020 22:46:26 GMT

Thanks for your input @rhall .

I changed my approach for the problem. I am using tMemorizeRows and tJavaFlex for my duplicate row check.

Using tMemorizeRows with 2 row count, I am checking 2 row at a time. Based on my condition, I need to update one column in the row.

So, in tJavaFlex based on my memorizerow data, I am able to update a column for my current row in context. But to update a column value for my previous row (matched row by condition using memorizerow), how can I get previous row to update any column with new value.

Re: How to update prev row after comparing with current and prev row?

Anonymous — Wed, 04 Mar 2020 23:03:16 GMT

The method you are looking for (to search the whole result rows) with a tMap is essentially what I was describing in my first suggestion. I am not sure how your new method will work if I am honest. Have you tried using the tHash components?

Re: How to update prev row after comparing with current and prev row?

dattasud — Thu, 05 Mar 2020 15:03:56 GMT

Hi @rhall

Yes, I checked the tHashOutput and tHashInput components and used it like below flow.

I am getting runtime exception with tHashInput_2 that its not initialized. The tHashInput_2 is linked to tHashOutput_2 which is having the duplicate rows.

I wrote condition in tMap for my duplicate row checks and updating the value in rows.

[statistics] connecting to socket on port 3722
[statistics] connected
Exception in component tHashInput_2 (Copy_of_AccountStatusChange)
java.lang.RuntimeException: The hash is not initialized : The hash must exist before you read from it
at stateofbusiness.copy_of_accountstatuschange_0_1.Copy_of_AccountStatusChange.tHashInput_2Process(Copy_of_AccountStatusChange.java:2601)
at stateofbusiness.copy_of_accountstatuschange_0_1.Copy_of_AccountStatusChange.tHashInput_1Process(Copy_of_AccountStatusChange.java:1511)
at stateofbusiness.copy_of_accountstatuschange_0_1.Copy_of_AccountStatusChange.runJobInTOS(Copy_of_AccountStatusChange.java:5655)
at stateofbusiness.copy_of_accountstatuschange_0_1.Copy_of_AccountStatusChange.main(Copy_of_AccountStatusChange.java:5504)
[statistics] disconnected

The tHashInput_2 is getting initiated from tHashInput_1. And also the this right side block is getting complied first then the actual main left side job. Is there any way to correct the flow. The flow should go from left to right.

Re: How to update prev row after comparing with current and prev row?

nivedhitha — Thu, 05 Mar 2020 17:34:58 GMT

@dattasud , Yeah with the currrent design, the hashinput subjob is executed at the same time as the salesforce connection. You have to connect the HashInput subjob on 'On subjob ok' trigger from tSalesforceInput

Re: How to update prev row after comparing with current and prev row?

dattasud — Thu, 05 Mar 2020 17:47:05 GMT

@nivedhitha Thanks for your input. The error is resolved.
Thanks @rhall for your help and time.

Re: How to update prev row after comparing with current and prev row?

Anonymous — Fri, 06 Mar 2020 17:40:52 GMT

Glad you got it sorted, and thanks to @nivedhitha for helping to resolve the usage problem