Readable database errors

Do you like forcing constraint validation down into the database, but dislike the native error messages returned by Postgres?

invalid input syntax for uuid: "foo"

invalid input value for enum account_status: "blah"

new row for relation "accounts" violates check constraint "accounts_balance_check"

null value in column \"id\" violates not-null constraint

This library attempts to parse those error messages and return error messages that you can expose via your API.

No id was provided. Please provide a id

Cannot write a negative balance

Invalid input syntax for type uuid: "foo"

Invalid account_status: "blah"

Can't save to payments because the account_id (91f47e99-d616-4d8c-9c02-cbd13bceac60) isn't present in the accounts table

A email already exists with this value (test@example.com)

In addition, this library exports common Postgres error codes, so you can check against them in your application.

Basic Usage

import dberror "github.com/Shyp/go-dberror"

func main() {
    _, err := db.Exec("INSERT INTO accounts (id) VALUES (null)")
    dberr := dberror.GetError(err)
    switch e := dberr.(type) {
    case *dberror.Error:
        fmt.Println(e.Error()) // "No id was provided. Please provide a id"
    default:
        // not a pq error
}

Database Constraints

Failed check constraints are tricky - the native error messages just say "failed", and don't reference a column.

So you can define your own constraint handlers, and then register them:

import dberror "github.com/Shyp/go-dberror"
import "github.com/lib/pq"

func init()
    constraint := &dberror.Constraint{
        Name: "accounts_balance_check",
        GetError: func(e *pq.Error) *dberror.Error {
            return &dberror.Error{
                Message:  "Cannot write a negative balance",
                Severity: e.Severity,
                Table:    e.Table,
                Detail:   e.Detail,
                Code:     string(e.Code),
            }
        },
    }
    dberror.RegisterConstraint(constraint)

    // test.AssertEquals(t, e.Error(), "Cannot write a negative balance")
}

If we get a constraint failure, we'll call your GetError handler, to get a well-formatted message.