Expression error after inner join using join snaps

Getting below expression error in mapper after join snaps:-
Expression worked for 7 previous documengts, but failed on document #8 with the error: $[’$’] is undefined

You cannot use that expression. That’ basically means “Get root from root”, or something like that, and is not valid. I know that your field is called “$” so a smart thing to do is first to remap the field.

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This error will occur if the key "$" does not exist in your 8th document. You can either:

  • change your expression to $.get('$') which will effectively produce a null value for $['$'] downstream
  • or if your error is in a Mapper, you can also check the image checkbox, which will also produce a null value (but also applies null-safe to all the fields in your mapper).