Support detect duplicated items in list

[jiaorenyu]

I have a use case:

columns:
  - name: n1
     type: string
  - gender: male
     type: string
  ...
  - gender: 1
     type: int

I want to check if there are some duplicated columns, I don't want it has duplicated columns.

[mildebrandt]

Hi, thanks for your interest in Yamale.

There is no ability to validate duplicated elements in a list with Yamale.

[jiaorenyu]

Hi, thanks for your interest in Yamale.

There is no ability to validate duplicated elements in a list with Yamale.

Thanks for the reply, can we support it in the future?

[mildebrandt]

This use case may be too complex than what we'd like to support in Yamale. If it was as simple as detecting duplicate items in a list, then I think we could support it. For example, changing your sample slightly:

columns:
  - name: n1
    type: string
  - gender: male
    type: string
  - gender: male
    type: string

We have two items in the list that equal {gender: male, type: string}. For your use case:

columns:
  - name: n1
    type: string
  - gender: male
    type: string
  - gender: 1
    type: int

There is one item of {gender: male, type: string} and the other of {gender: 1, type: int}. These would not be equal. You're looking to describe certain keys of a dictionary cannot be duplicated within a list, and I don't think that's something we can support while keeping the schema language simple enough.

You can write your own custom validator to support specific use cases: https://github.com/23andMe/Yamale#custom-validators

Please reach out if you have any problems writing your own validator.