proposal: encoding/json: Unmarshal string to number

[erikpa1]

Proposal Details

Hi, when working with external APIs and so on there area always some weirdos in this world, which sends numbers as a string in json {"data" : "50"} instead of {"data": 50} , this also happens when you you use some default form behavior in client side javascript library.

Could be nice define in json:"speed, isNumberString"

[ianlancetaylor]

CC @dsnet @mvdan

[gabyhelp]

Related Issues

• Proposal: encoding/json: add new tag for numbers to be string or number literals for unmarshalling #19175 (closed)

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[seankhliao]

the string json tag option already works.
https://go.dev/play/p/30p8aClQe9S

[dsnet]

Hi @erikpa1, thanks for the issue.

It seems to me that the "json" package already supports this with the ,string option?
For example:

type Foo struct {
    Speed int64 `json:"speed,string"`
}
var foo Foo
json.Unmarshal([]byte(`{"speed":"9000"}`), &foo)
fmt.Println(foo)

Regarding the use of stringified numbers being "weird", this is largely an artifact of JSON having JavaScript as its heritage, where numbers in JavaScript are float64. Thus, many JSON parsers will mangle 64-bit integers if sufficiently large since they cannot be accurately represented in a float64. The use of strings for wide integers became standard practice to work around this quirk. One could argue that JavaScript is the "weird" one.

[erikpa1]

@dsnet Thanks I will try :)