nil time.Time pointer works in insert, but not in update

[aktau]

I have this code:

type FeedArticle struct {
    Id          int64
    Feed        int64
    Reference   string
    Title       string
    Body        sql.NullString
    PublishedOn *time.Time
}

func (m *Model) MergeArticles(articles ...*FeedArticle) error {
    tx, err := m.db.Begin()
    if err != nil {
        return err
    }

    update, err := tx.Prepare(`
        UPDATE feed_articles
        SET    title         = $3::text
        ,      body          = $4::text
        ,      published_on  = $5::timestamptz
        WHERE  feed          = $2::integer
        AND    reference     = $1::text
    `)
    if err != nil {
        tx.Rollback()
        return err
    }

    insert, err := tx.Prepare(`
        INSERT INTO feed_articles (reference, feed, title, body, published_on)
        VALUES ($1::text, $2::integer, $3::text, $4::text, $5::timestamptz)
    `)
    if err != nil {
        tx.Rollback()
        return err
    }

    for _, a := range articles {
        // do a naive loop, later we should generate a bulk statement client
        // side
        fmt.Printf("Processing: %s, %d, %s, %v, %p\n", a.Reference, a.Feed,
            a.Title, a.Body, a.PublishedOn)
        res, err := update.ExecOne(a.Reference, a.Feed, a.Title, a.Body,
            a.PublishedOn)
        if err != nil {
            tx.Rollback()
            return err
        }

        // if we've managed to update an article, stop here
        if res.Affected() != 0 {
            continue
        }

        _, err = insert.ExecOne(a.Reference, a.Feed, a.Title, a.Body,
            a.PublishedOn)
        if err != nil {
            return err
        }

    }

    return tx.Commit()
}

And the second time I run it, it errors out with:

panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x0 pc=0x5c23b0]

goroutine 16 [running]:
runtime.panic(0x777180, 0xa99cb3)
        /usr/lib/go/src/pkg/runtime/panic.c:279 +0xf5
github.com/go-pg/pg.assertOneAffected(0x0, 0xc208103938, 0x0, 0x0)
        /home/vagrant/go/src/github.com/go-pg/pg/db.go:388 +0x30
github.com/go-pg/pg.(*Stmt).ExecOne(0xc208140f80, 0xc208103938, 0x5, 0x5, 0x5, 0x0, 0x0)
        /home/vagrant/go/src/github.com/go-pg/pg/stmt.go:75 +0xa2
bitbucket.org/aktau/lumamodel.(*Model).MergeArticles(0xc2080384d8, 0xc208107b00, 0x12, 0x20, 0x0
, 0x0)

Note that the FeedArticle.PublishedOn member is a nil pointer in this invocation (I checked). What's string is: this seems to work for the INSERT. I checked after a first run and the row is present in the DB (and the PublishedOn column is NULL).

Am I doing something wrong?

(I'm using a pointer to time.Time because I couldn't find a sql.NullTime type).

[aktau]

After looking at the backtrace, this seems to have little to do with the *time.Time being nil.

What's also strange is that on the first run, with an empty database, the res value gives 1 (!) as the Affected value. While I'm positive that there's not row it could have possible matched... very strange.

It almost seems like the UPDATE statement is inserting rows... am I going crazy?

[aktau]

Could it be that somehow, there can only be one prepared statement active at a time? And that the INSERT statement is overriding the UPDATE statement?

[vmihailenco]

Yeah, client did not support multiple statements in 1 transaction. Should be fixed by #24 . I will merge fix later today.

Also you are probably interested in RunInTransaction helper: http://godoc.org/gopkg.in/pg.v2#DB.RunInTransaction

[aktau]

Also you are probably interested in RunInTransaction helper:

Indeed I was. I already switched to it when I saw it earlier (even before you mentioned it :)). The docs are a bit spartan, but that function name was clear enough. I'll learn to inspect go-pg's source better.