go - 用 jsonapi 编码(marshal) slice

Question

我有一片结构，我想使用 https://github.com/google/jsonapi 编码它.

只有一个结构，一切正常。我只是传递一个指针作为第二个参数。

package main

import (
    "fmt"
    "os"

    "github.com/google/jsonapi"
)

type Spider struct {
    ID       int `jsonapi:"primary,spiders"`
    EyeCount int `jsonapi:"attr,eye_count"`
}

func main() {
    jsonapi.MarshalPayload(os.Stdout, &Spider{ID: 2, EyeCount: 12})
    // {"data":{"type":"spiders","id":"2","attributes":{"eye_count":12}}}
}

---

但是，当我尝试对 slice 执行相同操作时，情况就大不相同了。

首先，我将我的 slice 转换为指向这些结构的指针 slice (不知道在这里还能做什么，将指针传递给 slice 没有用)。

spiders := []Spider{Spider{ID: 1, EyeCount: 8}, Spider{ID: 2, EyeCount: 12}}

var spiderPointers []*Spider
for _, x := range spiders {
    spiderPointers = append(spiderPointers, &x)
}
jsonapi.MarshalPayload(os.Stdout, spiderPointers)

它有效。有点。这是问题所在:

{"data":[
  {"type":"spiders","id":"2","attributes":{"eye_count":12}},
  {"type":"spiders","id":"2","attributes":{"eye_count":12}}]}

重复最后一个元素并替换其他元素。

最后，我想出了一个可行的解决方案:

spiders := []Spider{Spider{ID: 1, EyeCount: 8}, Spider{ID: 2, EyeCount: 12}}
var spiderPointers []interface{}
for _, x := range spiders {
    var spider Spider
    spider = x
    spiderPointers = append(spiderPointers, &spider)
}

jsonapi.MarshalPayload(os.Stdout, spiderPointers)
// {"data":[{"type":"spiders","id":"1","attributes":{"eye_count":8}},
//          {"type":"spiders","id":"2","attributes":{"eye_count":12}}]}

但我确信一定有更好的方法，因此出现了这个问题。

Answer 1

想知道您能使用这样的东西吗？？

package main

import (
    "encoding/json"
    "fmt"
    "os"

    "github.com/google/jsonapi"
)

type Spider struct {
    ID       int `jsonapi:"primary,spiders"`
    EyeCount int `jsonapi:"attr,eye_count"`
}

func main() {
    // spiders is a slice of interfaces.. they can be unmarshalled back to spiders later if the need arises
    // you don't need a loop to create pointers either... so better in memory usage and a bit cleaner to read.. you can in theory load the []interface{} with a for loop as well since you mentioned getting this data from a db
    var spiders []interface{}
    spiders = append(spiders, &Spider{ID: 1, EyeCount: 8}, &Spider{ID: 2, EyeCount: 12})
    fmt.Println("jsonapi, MarshalPayload")
    jsonapi.MarshalPayload(os.Stdout, spiders)

    // test against marshall indent for sanity checking
    b, _ := json.MarshalIndent(spiders, "", " ")
    fmt.Println("marshall indent")
    fmt.Println(string(b))
}