Select and Get usage with sqlx - go

Question

I'm using go 1.10.3 and I'm trying to use the sqlx package to get one row and enter it to a struct with Get(), or get several rows and enter them to a slice with Select().
lets start with getting one row into a struct.
I created the following struct:
type PsqlProduct struct {
Id int64 `db:"product_id"`
Name string `db:"product_name"`
Desc sql.NullString `db:"product_desc"`
YearManufacture sql.NullInt64 `db:"year_manufacture"`
Quantity sql.NullInt64 `db:"quantity"`
}
for the query:
QUERY_SELECT_PRODUCT = `select wd.product.id as product_id,
trans_p_name.text as product_name,
trans_p_desc.text as product_desc,
wd.product.year_manufacture, wd.product.quantity
from wd.product
join wd.text_translation as trans_p_name
on trans_p_name.text_id = wd.product.product_name_trans_id and trans_p_name.lang_id=1
left join wd.text_translation as trans_p_desc
on trans_p_desc.text_id = wd.product.product_desc_trans_id and trans_p_desc.lang_id=1
where wd.product.id = $1
`
and I created the following function to get product by id:
func PsqlGetProductById(productId int) *Product {
product := new(PsqlProduct)
err := Psqldb.Get(&product, QUERY_SELECT_PRODUCT,productId)
if err != nil {
log.Fatalf("error: %v",err)
return nil
} else {
newp := Product{
ID: uint(product.Id),
Name: product.Name,
}
if product.Quantity.Valid {
newp.Quantity = uint16(product.Quantity.Int64)
}
if product.YearManufacture.Valid {
newp.YearManufacture = uint16(product.YearManufacture.Int64)
}
if product.Desc.Valid {
newp.Desc = product.Desc.String
}
return &newp
}
}
and I got the error
error: scannable dest type ptr with >1 columns (5) in result
it's as if Get() function is only for one column.. but the documentation clearly states it's not!
if I change the Get() function call to Psqldb.QueryRowx(QUERY_SELECT_PRODUCT, productId).StructScan(product)
then it does work.. but still.. trying to find out why Get() doesn't work.
next.. Select()
so this is the struct
type PsqlCategory struct {
Id int64 `db:"category_id"`
Name string `db:"category_name"`
ParentCategoryId sql.NullInt64 `db:"parent_category_id"`
}
sql query:
QUERY_SELECT_CATEGORIES = `
select category.id as category_id,
text_translation.text as category_name,
category.parent_category_id
from category
join text_translation on text_translation.text_id=category.category_name_trans_id
and text_translation.lang_id = 1`
and the function
func PsqlGetCategories() []Category {
categories := []PsqlCategory{}
err := Psqldb.Select(&categories, QUERY_SELECT_CATEGORIES)
if err != nil {
log.Fatalf("could not parse categories: %v", err)
return nil
}
var nCategories []Category
for _, cat := range categories {
newCat := Category{
Id: cat.Id,
Name: cat.Name,
}
if cat.ParentCategoryId.Valid {
newCat.ParentCategoryId = cat.ParentCategoryId.Int64
}
nCategories = append(nCategories, newCat)
}
return nCategories
}
and this is the error
could not parse categories: pq: relation "category" does not exist
it's like I totally misunderstood the usage of the sqlx library or I'm missing something..
any information regarding the issue would be greatly appreciated.

Answer 1

The problem arises because you're passing **PsqlProduct to Get which thinks that you want to scan the query result into the pointed to pointer, hence "... dest type ptr with >1 columns ...".
Just change:
err := Psqldb.Get(&product, QUERY_SELECT_PRODUCT,productId)
to:
err := Psqldb.Get(product, QUERY_SELECT_PRODUCT,productId)