如何获取unique_constraint违例的列名？

Question

I am using the pq driver and I'm wondering why the pq.Error gives an empty Column when I face a unique constraint violation.

I could parse Detail but is there any reason why Column would be empty? It would be preferable if I could just get email from Column instead of parsing Detail

Here is what the error looks like:

Severity:"ERROR"
Code:"23505"
Message:"duplicate key value violates unique constraint "unique_users""
Detail:"Key (email)=([e-mail]) already exists."
Hint:""
Position:""
InternalPosition:""
InternalQuery:""
Where:""
Schema:"public"
Table:"users"
Column:""
DataTypeName:""
Constraint:"unique_users"
File:"nbtinsert.c"
Line:"534"
Routine:"_bt_check_unique"

Unfortunately, the Column value is empty. I'm trying to come up with error messaging for my application and I'm wondering if there is some way to get that information so I can enhance the message why the entity was not created and let the caller know the field (email in this case) as well.

Answer 1

The specific error message (including the violated constraint and column/value) is in the field Detail.

EDIT:

I guess Column is empty, because the unique constraint might affect multiple columns. Constraint offers the constraint name, in combination with Schema and Table you can look up this constraint in pg_constraint. Field conkey might hold the references to the covered attributes.