There is no such distinction in json as a float vs. an int; they are just numbers. This is essentially a consequence of the javascript underpinnings of json.
Thomas On Thu, Mar 2, 2017 at 2:29 AM Basile Starynkevitch < bas...@starynkevitch.net> wrote: > Hello All, > > This could be related to issue #6384 > <https://github.com/golang/go/issues/6384> > > I want to JSON encode a float64 point number always as a JSON float, so > 1.0 should be encoded as 1.0 not as 1 because at decoding time I want to > distinguish them. > Conceptually, I am persisting in JSON format something which is somehow > close to some AST, or even to S-expressions (see below for details). So I > want a float 1.0 to be different of the integer 1. > > If you are curious, my exact code is commit 096ec00f53011b2a1b05ce > <https://github.com/bstarynk/monimelt/commit/096ec00f53011b2a1b05ceb8d14d4e65e88285d5> > on github, and when running go test -v objvalmo with my monimelt project > being last in my GOPATH I'm getting as output (amongst many other lines) > > json_emit v=-1.000000 of type objvalmo.FloatV > json_emit buf: -1 > > and I would like that second line to be at least json_emit buf: -1.0 > because I need to separate objvalmo.FloatV from objvalmo.IntV types > > I played with the following json/encoding example > <https://golang.org/pkg/encoding/json/#example_RawMessage_marshal> and > changed it (by adding some mass being 1.0) to > > package main > > import ( > "encoding/json" > "fmt" > "os" > ) > > func main() { > h := json.RawMessage(`{"precomputed": true}`) > > c := struct { > Header *json.RawMessage `json:"header"` > Body string `json:"body"` > Mass float64 `json:"mass"` > }{Header: &h, Body: "Hello Gophers!", Mass: 1.0} > > b, err := json.MarshalIndent(&c, "", "\t") > if err != nil { > fmt.Println("error:", err) > } > os.Stdout.Write(b) > > } > > > > > and expected the output to contain "mass" : 1.0 but it still gives a line > with only "mass": 1 without any decimal point. Is there any way to > change that and get that decimal point? > > > More generally, I don't understand well how should I use JSON facilities > in Go. IMHO, there are two approaches: one is using go reflection > facilities, and claim to be able to serialize most arbitrary values. > another is not using them at all (and this is what I would prefer) by > constructing some explicit data in memory mimicking JSON format. FWIW, I > care a bit about performance. > > To explain my issues, let us imagine that I want to serialize (and > unserialize) in JSON format some s-expressions > <https://en.wikipedia.org/wiki/S-expression> (or some program of a micro > Scheme or micro Lisp interpreter), with both lists and vectors as composite > types, with the additional constraint that some symbols should not be > serialized (and we'll output the null JSON value for them instead) For > simplicity assume that we have only alphabetical symbols like xy foo bar > efg Let us suppose that we want to ignore all symbols starting with a > vowel (so we ignore efg here). so (foo 1 #(2 xy) (bar "ab" efg -1.0 > "cd")) is an example of such s-expr.. It is a list of 4 elements. The > third element is a vector #(2 xy) of 2 components. The 4th and last > element is a list (bar "ab" efg -1.0 "cd") of 5 elements whose 3rd > element is the symbol efg which, since starting with a vowel, should be > ignored and serialized as null and whose 4th element is the floating > point -1.0 (not the integer -1). I would like to serialize that S-expr > value as e.g. > { "list" : [ { "symb" : "foo" }, 1, { "vect" : [ 2, { "symb" : "xy" } ] }, > { "list" : [ { "symb" : "bar" }, null, -1.0, "cd" ] } ] } > > > Actually, I am not exacty coding a microScheme. I haved shared objects (of > *ObjectMo type) and values (of ValueMo type) inside objects (every object > has a map and a slice of values). I want to persist them in JSON inside an > Sqlite database, but some objects are transient and non-persistent (so I > would encode them as null). All objects have a *unique* id like > _0ECuE7b9XhQ_3HvWl3RGhD6 > > Any advices are welcome. In particular, I am a bit afraid of the > reflection approach (because I want serialization & deserialization to not > be too slow, and I really need to master the JSON representation). > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
