如何在Go中将结构指针转换为类型指针列表

huangapple go评论81阅读模式
英文:

how to convert a struct pointer to list of type pointers in go

问题

我有一个类似的结构体:

type inv struct {
    ID   int     `json:"id"`
    Name string  `json:"name"`
}

我正在从数据库查询一些数据(假设没有错误):

rows, err := db.Query("select id, name from inv_table")

通常情况下,我需要通过扫描来从行中提取数据:

var i inv
for rows.Next() {
    rows.Scan(&i.ID, &i.Name)
}

我认为这可能会起作用(明天要测试一下):

var i inv
for rows.Next() {
    var x []interface{} = []interface{}{&i.ID, &i.Name}
    rows.Scan(x...)
}

实际上,查询结果集中还有更多的列。

rows.Scan(&i)

或者至少:

rows.Scan(getExportedValuePointers(&i)...)

我想我可以编写一些类似于encode/xml或encode/json的反射代码,但我希望有人已经做过了。

更新:以下代码按预期工作,但不是我想要的:

package main
import "fmt"
type inv struct {
    A int
    B string
}
func main() {
    var i inv
    fmt.Printf("hello\n")
    n, err := fmt.Sscan("1 c", &i.A, &i.B)
    fmt.Printf("retval: %d %#v\n", n, err)
    fmt.Printf("retval: %d, %s, %d %#v\n", i.A, i.B, n, err)
    j := []interface{}{&i.A, &i.B}
    k := []interface{}{i.A, i.B}
    n, err = fmt.Sscan("2 d", j... )
    fmt.Printf("retval: %d, %s, %d %#v\n", i.A, i.B, n, err)
    fmt.Printf("retval: %d, %s\n", k... )
}
英文:

I have a struct that looks like:

type inv struct {
    ID   int     `json:"id"`
    Name string  `json:"name"`
}

I'm querying some data from the database(assuming there are no errors):

rows, err := db.Query("select id, name from inv_table")

Normally, I'd have to pull the data from the row by scanning

var i inv
for rows.Next() {
    rows.Scan(&i.ID, &i.Name)
}

I think this might work (to be tested tomorrow):

var i inv
for rows.Next() {
    var x []interface{} = [&i.ID, &i.Name]
    rows.Scan(x... )
}

In actuality I have many more columns in the result set from the query.

rows.Scan(&i)

or at least:

rows.Scan(getExportedValuePointers(&i)... )

I suppose I could always write some sort of encoder, however, it seems to me that there should be something in the box already.

** I realize that I could always write some reflection code similar to the encode/xml or encode/json ... but I'm hoping that someone has already done it.

UPDATE: The following code works as expected but not as I want:

package main
import "fmt"
type inv struct {
    A int
    B string
}
func main() {
    var i inv
    fmt.Printf("hello\n")
    n, err := fmt.Sscan("1 c", &i.A, &i.B)
    fmt.Printf("retval: %d %#v\n", n, err)
    fmt.Printf("retval: %d, %s, %d %#v\n", i.A, i.B, n, err)
    j := []interface{}{&i.A, &i.B}
    k := []interface{}{i.A, i.B}
    n, err = fmt.Sscan("2 d", j... )
    fmt.Printf("retval: %d, %s, %d %#v\n", i.A, i.B, n, err)
    fmt.Printf("retval: %d, %s\n", k... )
}

答案1

得分: 2

如果你正在寻找一个可以自动将你的SQL查询绑定到你的"inv"结构体的包,那么可以看一下gorp:

https://github.com/coopernurse/gorp

英文:

If you're looking for a package that will automatically bind your SQL query to your "inv" struct then take a look at gorp:

https://github.com/coopernurse/gorp

答案2

得分: 0

没有自动完成这个任务的方法,但是你可以使用反射包(reflect package)编写一个函数来实现。

英文:

There is nothing to do this automatically, but you could write a function using the reflect package to do it.

huangapple
  • 本文由 发表于 2012年12月11日 10:12:38
  • 转载请务必保留本文链接:https://go.coder-hub.com/13812560.html
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