feat: added raw query calls

[josearomeroj]

Added raw query support: #593

[vmihailenco]

Hey,

The suggested API looks like this:

err := db.Raw(query, args...).Scan(ctx, &strct)
err := db.Raw(query, args...).Scan(ctx, &slice)
err := db.Raw(query, args...).Scan(ctx, &var1, &var2)

The implementation should look like this:

func (db *DB) Raw(query string, args ...interface{}) *RawQuery {
    return &RawQuery{
        db: db,
        query: query,
        args: args,
    }
}

type RawQuery struct {
    db *DB
    query string
    args ...interface{}
}

func (q *RawQuery) Scan(ctx context.Context, dest ...interface{}) error {
    // extract and reuse Scan implementation from SelectQuery.Scan
    // to format the query, use query := db.format(q.query, q.args)
    return scanModel(...)
}

Does that make sense?

[josearomeroj]

Did you mean something like that?

[vmihailenco]

Did you mean something like that?

Yes, exactly 👍 Could you add a simple test like db.Raw("SELECT ?", 123).Scan(ctx, &num)?

[vmihailenco]

This can be return fmter.AppendQuery(b, q.query, q.args), nil

[josearomeroj]

Let me know if you see the need to change something else

[vmihailenco]

Very good - thanks 👍