英文:
golang querying database using Gorm and returning json in http response
问题
我是你的中文翻译助手，以下是你提供的代码的翻译：
我刚开始学习Go语言，并且正在使用Gorm来查询我的PostgreSQL数据库，但是在以字典格式返回数据时遇到了问题，其中宝可梦的类型作为键，对应一个包含该类型所有宝可梦的数组。
> json: 无法将对象解组为类型为[]models.Pokemon的Go值
以下是我的代码：
type Pokemon struct {Name string `db:"name"`Type string `db:"type"`}pokemonTypes := [6]string{"fire","electric","water","grass",}var retData struct {Poke []Pokemon}m := make(map[string][]Pokemon)for _, t := range pokemonTypes {pokemon := DB.Where(&Pokemon{Type: t}).Find(&retData.Poke)p, _ := json.Marshal(pokemon)err = json.Unmarshal(p, &retData.Poke) // 在这里出错if err != nil {fmt.Println(err)}m[category] = retData.Poke}data, _ := json.Marshal(m)w.Write(data) // HTTP响应
我在数据库中有以下数据：
name | type----------------------pikachu | electriccharmander | fireblaziken | firevenusaur | grasstreeko | grasssquirtle | water
我希望以以下JSON格式返回数据：
{"electric": [{"name": "pikachu", "type": "electric"},],"fire": [{"name": "charmander", "type": "fire"},{"name": "blaziken", "type": "fire"}],"grass": [{"name": "venusaur", "type": "grass"},{"name": "treeko", "type": "grass"},],"water": [{"name": "squirtle", "type": "water"},]}
英文:
I'm new to Go and am using Gorm to query my postgres database but am having trouble returning my data in a dictionary format, where the pokemon's type serves as a key to an array of all the pokemon of that type
> json: cannot unmarshal object into Go value of type []models.Pokemon
here's my code:
type Pokemon struct {Name string `db:"name"`Type string `db:"type"`}pokemonTypes := [6]string{"fire","electric","water","grass",}var retData struct {Poke []Pokemon}m := make(map[string][]Pokemon)for _, t := range pokemonTypes {pokemon := DB.Where(&Pokemon{Type: t}).Find(&retData.Poke)p, _ := json.Marshal(pokemon)err = json.Unmarshal(p, &retData.Poke) // getting error hereif err != nil {fmt.Println(err)}m[category] = retData.Poke}data, _ := json.Marshal(m)w.Write(data) // http repsonse
I have this in my database
name | type----------------------pikachu | electriccharmander | fireblaziken | firevenusaur | grasstreeko | grasssquirtle | water
I want to return data in this json format
{“electric”: [{"name": "pikachu", "type": "electric"},],"fire": [{"name": "charmander", "type": "fire"},{"name": "blaziken", "type": "fire"}],"grass": [{"name": "venusaur", "type": "grass"},{"name": "treeko", "type": "grass"},],"water": [{"name": "squirtle", "type": "water"},]}
答案1
得分: 2
DB.Where(&Pokemon{Type: t}).Find(&retData.Poke) 实际上返回了 *db 指针，你可以使用它来链式调用其他方法。
当你执行 .Find(&retData.Poke) 时，已经将 postgre 行反序列化到了你的结构体切片中。因此，pokemon 实际上不是你想象中的那样。
现在只剩下将 .Find() 与 .Error() 链接起来，以便返回并检查查询中的任何错误。就像这样：
for _, t := range pokemonTypes {err := DB.Where(&Pokemon{Type: t}).Find(&retData.Poke).Error()if err != nil {fmt.Println(err)return}p, _ := json.Marshal(retData.Poke)err = json.Unmarshal(p, &retData.Poke)if err != nil {fmt.Println(err)return}m[category] = retData.Poke}
希望对你有所帮助！
英文:
DB.Where(&Pokemon{Type: t}).Find(&retData.Poke) esentially returns back the *db pointer which you can use to chain further methods.
You're already deserializing postgre rows into your struct slice when you do .Find(&retData.Poke). Thus, pokemon isn't actually what you think it is.
The only thing left now is to chain .Find() with a .Error() so that you can return and check any error in your query. Just like this :
for _, t := range pokemonTypes {err := DB.Where(&Pokemon{Type: t}).Find(&retData.Poke).Error()if err != nil {fmt.Println(err)return}p, _ := json.Marshal(retData.Poke)err = json.Unmarshal(p, &retData.Poke)if err != nil {fmt.Println(err)return}m[category] = retData.Poke}
Hope it helps!
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