2017-08-26 21:53
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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{

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 here
    if err != nil {
    m[category] = retData.Poke

data, _ := json.Marshal(m) 
w.Write(data)  // http repsonse

I have this in my database

name       | type
pikachu    | electric
charmander | fire
blaziken   | fire
venusaur   | grass
treeko     | grass
squirtle   | 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"},
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1条回答 默认 最新

  • douduan4116 2017-08-26 22:49

    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 {
        p, _ := json.Marshal(retData.Poke)
        err = json.Unmarshal(p, &retData.Poke) 
        if err != nil {
        m[category] = retData.Poke

    Hope it helps!

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