Populate generated struct example. about jsongen

[bemasher]

Source file format.json:

{
    "format": {
        "bit_rate": "4236261",
        "duration": "2554.144000",
        "filename": "video.mkv",
        "format_long_name": "Matroska / WebM",
        "format_name": "matroska,webm",
        "nb_streams": 2,
        "size": "1352502623",
        "start_time": "0.000000",
        "tags": {
            "creation_time": "2012-10-11 12:29:58"
        }
    }
}

Generate type with JSONGen:

$ jsongen format.json
type _ struct {
        Format struct {
                Duration       string `json:"duration"`
                FormatLongName string `json:"format_long_name"`
                FormatName     string `json:"format_name"`
                NbStreams      int64  `json:"nb_streams"`
                StartTime      string `json:"start_time"`
                BitRate        string `json:"bit_rate"`
                Size           string `json:"size"`
                Tags           struct {
                        CreationTime string `json:"creation_time"`
                } `json:"tags"`
                Filename string `json:"filename"`
        } `json:"format"`
}

Populate generated struct with source file:

package main

import (
    "encoding/json"
    "fmt"
    "log"
    "os"
)

const (
    SourceFile = "format.json"
)

// Type generated with JSONGen.
type FFProbe struct {
    Format struct {
        Duration       string `json:"duration"`
        FormatLongName string `json:"format_long_name"`
        FormatName     string `json:"format_name"`
        NbStreams      int64  `json:"nb_streams"`
        StartTime      string `json:"start_time"`
        BitRate        string `json:"bit_rate"`
        Size           string `json:"size"`
        Tags           struct {
            CreationTime string `json:"creation_time"`
        } `json:"tags"`
        Filename string `json:"filename"`
    } `json:"format"`
}

func main() {
    // Open source file.
    sourceFile, err := os.Open(SourceFile)
    if err != nil {
        log.Fatal("Error opening source file:", err)
    }
    defer sourceFile.Close()

    // Make a new json decoder reading from the source string.
    ffprobeDecoder := json.NewDecoder(sourceFile)

    // Decode into ffprobe.
    var ffprobe FFProbe
    err = ffprobeDecoder.Decode(&ffprobe)
    if err != nil {
        log.Fatal("Error decoding ffprobe:", err)
    }

    // Print populated ffprobe.
    fmt.Printf("%+v\n", ffprobe)
}

Output:

{Format:{Duration:2554.144000 FormatLongName:Matroska / WebM FormatName:matroska,webm NbStreams:2 StartTime:0.000000 BitRate:4236261 Size:1352502623 Tags:{CreationTime:2012-10-11 12:29:58} Filename:video.mkv}}

[emilebosch]

Hi Douglas, Thanks but I meant the other way around. I.e. creating a struct and then serializing it to JSON.

[bemasher]

That's not really related to this project. But it would operate more or less the same way as the example above just substituting NewDecoder with NewEncoder or any of the Marshal functions.