I've been playing with Go recently and it's awesome. The thing I can't seem to figure out (after looking through documentation and blog posts) is how to get the time.Time
type to format into whatever format I'd like when it's encoded by json.NewEncoder.Encode
Here's a minimal Code example:
package main type Document struct { Name string Content string Stamp time.Time Author string } func sendResponse(data interface{}, w http.ResponseWriter, r * http.Request){ _, err := json.Marshal(data) j := json.NewEncoder(w) if err == nil { encodedErr := j.Encode(data) if encodedErr != nil{ //code snipped } }else{ //code snipped } } func main() { http.HandleFunc("/document", control.HandleDocuments) http.ListenAndServe("localhost:4000", nil) } func HandleDocuments(w http.ResponseWriter,r *http.Request) { w.Header().Set("Content-Type", "application/json") w.Header().Set("Access-Control-Allow-Origin", "*") switch r.Method { case "GET": //logic snipped testDoc := model.Document{"Meeting Notes", "These are some notes", time.Now(), "Bacon"} sendResponse(testDoc, w,r) } case "POST": case "PUT": case "DELETE": default: //snipped } }
Ideally, I'd like to send a request and get the Stamp field back as something like May 15, 2014
and not 2014-05-16T08:28:06.801064-04:00
But I'm not really sure how, I know I can add json:stamp
to the Document type declaration to get the field to be encoded with the name stamp instead of Stamp, but I don't know what those types of things are called, so I'm not even sure what to google for to find out if there is some type of formatting option in that as well.
Does anyone have a link to the an example or good documentation page on the subject of those type mark ups (or whatever they're called) or on how I can tell the JSON encoder to handle time.Time
fields?
Just for reference, I have looked at these pages: here and here and of course, at the official docs
JSON does not have a built-in type for date/time values. The general consensus is to store the date/time value as a string in ISO 8601 format. Example { "myDateTime": "2018-12-10T13:45:00.000Z" }
You can get the value of the date field as String by calling the getText() method of JsonParser class and then you can simply convert it into a Date object by using the parse() method of SimpleDateFormat, as you normally parse Date in Java.
JSON does not directly support the date format and it stores it as String. However, as you have learned by now that mongo shell is a JavaScript interpreter and so in order to represent dates in JavaScript, JSON uses a specific string format ISODate to encode dates as string.
Json library parses and writes DateTime and DateTimeOffset values according to the ISO 8601-1:2019 extended profile.
What you can do is, wrap time.Time as your own custom type, and make it implement the Marshaler
interface:
type Marshaler interface { MarshalJSON() ([]byte, error) }
So what you'd do is something like:
type JSONTime time.Time func (t JSONTime)MarshalJSON() ([]byte, error) { //do your serializing here stamp := fmt.Sprintf("\"%s\"", time.Time(t).Format("Mon Jan _2")) return []byte(stamp), nil }
and make document:
type Document struct { Name string Content string Stamp JSONTime Author string }
and have your intialization look like:
testDoc := model.Document{"Meeting Notes", "These are some notes", JSONTime(time.Now()), "Bacon"}
And that's about it. If you want unmarshaling, there is the Unmarshaler
interface too.
Perhaps another way will be interesting for someone. I wanted to avoid using alias type for Time.
type Document struct { Name string Content string Stamp time.Time Author string } func (d *Document) MarshalJSON() ([]byte, error) { type Alias Document return json.Marshal(&struct { *Alias Stamp string `json:"stamp"` }{ Alias: (*Alias)(d), Stamp: d.Stamp.Format("Mon Jan _2"), }) }
Source: http://choly.ca/post/go-json-marshalling/
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