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golang.tokyo #10 x WomenWhoGoTokyo
interfaceͱͷ͖߹͍
micchie@WomenWhoGoTokyo
©micchie Women Who go Tokyo, 2017 1
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WomenWhoGoTokyo
αϯϑϥϯγείൃͷ, ঁੑͷGoݴޠͷίϛϡχςΟͰ͢ɻ
ݱࡏ11Χࠃ(ࢢผͰ25ڌ
❗
)ఔͰߦΘΕ͓ͯΓ, ౦ژ2016
4݄ʹൃ͠·ͨ͠ɻ
݄ʹ1ճ, ฏͷ19͔࣌ΒͰू·Γ, ษڧձΛߦ͍ͬͯ·͢ɻ
ܦݧεΩϧ·͍ͬͨ͘·ͤΜɻॳΊͯͷํࢀՃ͍͢͠
ձΛࢦ͍ͯ͠·͢㷉◔ϖ◔ʔ
©micchie Women Who go Tokyo, 2017 2
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ʕ•ᴥ•ʔʻͳ͠Λ͍ͨ͜͠ͱ
interfaceʹ͍ͭͯ
͜Μͳ෩ʹΓ·ͨ͠
©micchie Women Who go Tokyo, 2017 3
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͘͢͝టष͍Ͱ͢ɻ
©micchie Women Who go Tokyo, 2017 4
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ʕ•ᴥ•ʔʻࢥ͍͜Έ
͔ͬ͠Γͱͨ͠ܕ͚ݴޠͰ͋Δ͕Ώ͑ʹ
ॊೈͳऔѻ͍͍͠ͷͰͳ͍͔
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ʕ•̀ᴥ•́ʔʻࣗ༝ͳߏͷJsonϑΝΠϧΛऔΓࠐΈ͍ͨΜͰ͢
ʕ•́ᴥ•̀ʔʻݹʹઃܭ͞Εͨڥ͔Β৽͍͠ͷʹҠߦ͍ͨ͠ΜͰ͢
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͜Μͳײ͡ͷJSONΛ...
[
{
"11": ["ΞϝϦΧάϚ", "ผ໊ΞϝϦΧΫϩΫϚɻϓʔ͞ΜͷϞσϧɻ", 100]
},
{
"12": ["πΩϊϫάϚ", "टͷ෦͕ന͍ໟͰࡾ݄ঢ়ʹݟ͑Δ͜ͱ͔ΒπΩϊϫάϚͱݺΕΔɻ", 90]
},
{
"13": ["ϋΠΠϩάϚ", "ผ໊άϦζϦʔɻώάϚͷؒɻ", 30]
},
{
"14": ["ϗοΩϣΫάϚ", "γϩΫϚɻۃʹ͍Δ͕ɺೆۃʹ͍ͳ͍ɻ্࠷େͷ৯्ɻݮ͍ͬͯΔɻ", 80]
},
{
"15": ["ϚϨʔάϚ", "খ͕͘͞ѱ͘ɺઉ͕͍ɻύσΟϯτϯɻ", 50]
}
]
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͜ΜͳߏͰཧͯ͠, ಉ͡Α͏ʹग़ྗ͍ͨ͠ɻ
DataBase:
CREATE TABLE `animals` (
`id` bigint NOT NULL PRIMARY KEY,
`name` varchar(255) NOT NULL,
`description` text NOT NULL,
`rate` int NOT NULL
)
Struct:
type Animals struct {
ID uint `json:"id"`
Name string `json:"name"`
Description string `json:"description"`
Rate int `json:"rate"`
}
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ૉʹAnimalsߏମΛjson.Marshal͢Δͱ, ԼهͷΑ͏ʹͳΔɻ
[
{
"id": 11,
"name": "ΞϝϦΧάϚ",
"description": "ผ໊ΞϝϦΧΫϩΫϚɻϓʔ͞ΜͷϞσϧɻ",
"rate": 100
},
{
"id": 12,
"name": "πΩϊϫάϚ",
"description": "टͷ෦͕ന͍ໟͰࡾ݄ঢ়ʹݟ͑Δ͜ͱ͔ΒπΩϊϫάϚͱݺΕΔɻ",
"rate": 90
},
...
...
{
"id": 15,
"name": "ϚϨʔάϚ",
"description": "খ͕͘͞ѱ͘ɺઉ͕͍ɻύσΟϯτϯɻ",
"rate": 50
}
]
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ͦ͜ͰinterfaceͰΰχϣΰχϣ͢Δͱ...
...
var list []interface{}
var row Animals
for rows.Next() {
...
...
id := fmt.Sprint(row.ID) // IDΛstringʹ
descriptions := map[string]interface{}{id: []interface{}{row.Name, row.Description, row.Rate}}
list = append(list, descriptions)
}
...
j, err := json.Marshal(list)
...
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json.Unmarshal͢Δͱ...
&[
map[11:[ΞϝϦΧάϚ ผ໊ΞϝϦΧΫϩΫϚɻϓʔ͞ΜͷϞσϧɻ 100]]
map[12:[πΩϊϫάϚ टͷ෦͕ന͍ໟͰࡾ݄ঢ়ʹݟ͑Δ͜ͱ͔ΒπΩϊϫάϚͱݺΕΔɻ 90]]
map[13:[ϋΠΠϩάϚ ผ໊άϦζϦʔɻώάϚͷؒɻ 30]]
map[14:[ϗοΩϣΫάϚ γϩΫϚɻۃʹ͍Δ͕ɺೆۃʹ͍ͳ͍ɻ্࠷େͷ৯्ɻݮ͍ͬͯΔɻ 80]]
map[15:[ϚϨʔάϚ খ͕͘͞ѱ͘ɺઉ͕͍ɻύσΟϯτϯɻ 50]]
]
͜ͷΑ͏ʹ֨ೲ͞ΕΔͷͰ, 1ߦͣͭॲཧΛ͍ͯ͘͠ɻ
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for _, row := range list {
var animal Animals
for k, r := range row.(map[string]interface{}) {
i, _ := strconv.Atoi(k) // keyJSON্stringͷͨΊ
animal.ID = uint(i)
v := r.([]interface{})
// fmt.Println(v)
// [ΞϝϦΧάϚ ผ໊ΞϝϦΧΫϩΫϚɻϓʔ͞ΜͷϞσϧɻ 100]
animal.Name = v[0].(string)
animal.Description = v[1].(string)
animal.Rate = int(v[2].(float64))
}
...
// insertॲཧ
}
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ʕ•̀ᴥ•́ʔʻࣗ༝ͳߏͷJsonϑΝΠϧΛऔΓࠐΈ͍ͨΜͰ͢
ʕ•́ᴥ•̀ʔʻݹʹઃܭ͞Εͨڥ͔Β৽͍͠ͷʹҠߦ͍ͨ͠ΜͰ͢
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;Δ͍Ո͔Β͋ͨΒ͍͠ՈʹҾͬӽ͠Λ͍ͨ͠ɻ#1
type (
Before struct {
ID uint `db:"id"`
PostalCode sql.NullInt64 `db:"postal_code"`
Prefecture string `db:"prefecture"`
Address sql.NullString `db:"address"`
Hoge sql.NullString `db:"hoge"`
}
After struct {
ID uint `db:"id"`
PostalCode sql.NullInt64 `db:"postal_code"`
Prefecture string `db:"prefecture"`
Address sql.NullString `db:"address"`
Hoge string `db:"hoge"`
}
)
#1 1ςʔϒϧͷΈൈਮ, HogeͷΈ͕ܕ͕ҟͳΔέʔεɻ
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ಉ͡ܕಉ࢜interfaceͰѻ͑·ͨ͠ɻ
func main() {
...
to := &After{
PostalCode: toYurufuwa(Before.PostalCode).(sql.NullInt64)
Prefecture: toYurufuwa(Before.Prefecture).(string)
Address: toYurufuwa(Before.Address).()sql.NullString
Hoge: toHoge(Before.Hoge)
}
...
}
func toYurufuwa(before interface{}) interface{} {
return before
}
func toHoge(before sql.NullString) string {
if !before.Valid {
return HOGE_DEFAULT
}
returne before.String
}
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ͱ͜ΖͰ, Nullͳ߲Λѻ͏ͱ͖Կ͕࠷దͳΜͰ͠ΐ͏͔...?
1. *string *int
2. sql.NullString sql.NullInt64
3. `ͦͦNullڐՄͳઃܭΛ͠ͳ͍
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ͱ͜ΖͰ, database/sqlͷcolumnsͲ͏ॻ͍͍ͯ·͔͢...?
func (b Before) TableName() string {
return "before_table_name"
}
func (b Before) columns() (s []string) {
t := reflect.TypeOf(c)
for i := 0; i < t.NumField(); i++ {
field := t.Field(i)
s = append(s, field.Tag.Get("db"))
}
return s
}
...
sql := fmt.Sprintf(
"SELECT %s FROM %s",
strings.Join(Before.columns(), ","),
Before.TableName(),
)
...
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• ϥϕϧ
• @mi-bear, @micchiebear
• Ϩϕϧ
• ےઓ࢜ (15.0)
• Gopher (1.5)
• Vim (0.3)
• ଐੑ, ܕ
•
!
,
"
,
#
, 3DS
• גࣜձࣾϦϒηϯε
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Thanks!
Love Gophers
Love Gophers The Go gopher was designed by Renée French.
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