I have a JSON object that looks like this:
{"API version":"1.2.3"}
And I want to convert it to an object it using the json.Unmarshal() function in go. According to this blog post:
How does
Unmarshalidentify the fields in which to store the decoded data? For a given JSON key"Foo",Unmarshalwill look through the destination struct's fields to find (in order of preference):
- An exported field with a tag of
"Foo"(see the Go spec for more on struct tags),- An exported field named
"Foo", or- An exported field named
"FOO"or"FoO"or some other case-insensitive match of"Foo".
This is confirmed by the unmarshal documentation.
Since "API version" has a space in it, which is not a valid go identifier, I used a tag on the field:
type ApiVersion struct {
Api_version string "API version"
}
And I try to unmarshal it like so:
func GetVersion() (ver ApiVersion, err error) {
// Snip code that gets the JSON
log.Println("Json:",string(data))
err = json.Unmarshal(data,&ver)
log.Println("Unmarshalled:",ver);
}
The output is:
2014/01/06 16:47:38 Json: {"API version":"1.2.3"}
2014/01/06 16:47:38 Unmarshalled: {}
As you can see, the JSON isn't being marshalled into ver. What am I missing?
The encoding/json module requires that the struct tags be namespaced. So you instead want something like:
type ApiVersion struct {
Api_version string `json:"API version"`
}
This is done so that the json struct tags can co-exist with tags from other libraries (such as the XML encoder).