I know that when Postgres raises a duplicate key exception, it usually gives the value of the duplicate element in the detail of the exception itself.
ERROR: duplicate key value violates unique constraint "name_of_pkey"
DETAIL: Key (field_name)=(value) already exists.
From C#, how can i get that value from a NpgSqlException (NpgSql 3.1.7.0) now that the field Details has been removed from the exception class?
As mentioned in the 3.1 migration notes, in Npgsql 3.1 PostgreSQL errors are thrown as PostgresException, which extends NpgsqlException. NpgsqlExceptin is thrown for various client-side errors (e.g. networking).
You'll find the Detail property on PostgresException.