Basic issue: CDT one to Many for comments

ManuelHTG

A Score Level 1

over 5 years ago

Hi All,

I am quite new to Appian, so facing my first issue where I don't see how to make progress with the documentation (and I bet is very simple!).

I have a CDT 'main' that has another CDT 'commentslog' inside (relation one to many). The second auxiliar CDT is to track comments from the users in the different tasks/forms.

I am only using one CDT on my process. Each form use the same PV, and in each form the user can modify this 'main' CDT and can add a (new) comment with a text box.

The problem that I have is that this "new" comment is the same one, it is overwritten in each step, as I am not managing to make it a new item in the array of comments. On the Database what I see is one 'main' CDT with only one comment per process initiated.

Did anyone face a similar issue or could bring me some light?

Thanks and have a nice weekend!

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0 ChristineH
Certified Lead Developer
over 5 years ago

Are you saying you have a CDT with a nested CDT? If so, make sure in the main CDT description the nested one is marked as multiples.

I don’t usually use nested CDTs. I would create two CDTs and put a foreign key in the child table that stores the primary key of the parent. Then you would have two CDTs and two PVs and can work with them as needed.
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0 ChristineH
Certified Lead Developer
over 5 years ago

Are you saying you have a CDT with a nested CDT? If so, make sure in the main CDT description the nested one is marked as multiples.

I don’t usually use nested CDTs. I would create two CDTs and put a foreign key in the child table that stores the primary key of the parent. Then you would have two CDTs and two PVs and can work with them as needed.
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0 ManuelHTG
A Score Level 1
over 5 years ago in reply to ChristineH

Thanks Christine for the reply. Yes, I am using nested CDT's.
You are right, checking further in the community, many people advise to not use nested CDT for many reasons (including performance), so I will try that instead. I am still curious if it would be possible to do as I was trying to..
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0 chandu
A Score Level 2
over 5 years ago in reply to ManuelHTG

Hi manuelh,
We generally will not follow the nested CDT approach if we are persisting through Appian using WTDSE.
please go through the below discussion link.
community.appian.com/.../49581

Also there are some advantages and disadvantages in using Nested CDTs. But I prefer using of the nested CDTs if we have one to one relationship for persistence. And I use query entities in retrieving specific columns not Query rules which will pull the nested cdt elements.
In one to many relation ship, we commonly see the n+1 problem that is described below. So I avoid using nested CDT's
community.appian.com/.../database-performance-best-practices
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0 ManuelHTG
A Score Level 1
over 5 years ago in reply to chandu

Thanks, I see.

I was trying to make it simpler by reducing the amount of PV that I use. I see it is not a good idea as it brings more issues than anything else.
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