读取文件中的多个 yaml

Question

How does one parse multiple yamls in a file similar to how kubectl does it?

example.yaml

---
a: Easy!
b:
  c: 0
  d: [1, 2]
---
a: Peasy!
b:
  c: 1000
  d: [3, 4]

Answer 1

There's a difference in behavior between gopkg.in/yaml.v2 and gopkg.in/yaml.v3:

V2: https://play.golang.org/p/XScWhdPHukO V3: https://play.golang.org/p/OfFY4qH5wW2

Both implementations produce an incorrect result IMHO but V3 is apparently slightly worse.

There's a workaround. If you slightly change code in the accepted answer, it works correctly and in the same fashion with both versions of yaml package: https://play.golang.org/p/r4ogBVcRLCb

Answer 2

Solution I found using gopkg.in/yaml.v2 :

package main

import (
    "bytes"
    "fmt"
    "io/ioutil"
    "log"
    "path/filepath"

    "gopkg.in/yaml.v2"
)

type T struct {
        A string
        B struct {
                RenamedC int   `yaml:"c"`
                D        []int `yaml:",flow"`
        }
}

func main() {
    filename, _ := filepath.Abs("./example.yaml")
    yamlFile, err := ioutil.ReadFile(filename)
    if err != nil {
        panic(err)
    }

    r := bytes.NewReader(yamlFile)

    dec := yaml.NewDecoder(r)

    var t T
    for dec.Decode(&t) == nil {

      fmt.Printf("a :%v\nb :%v\n", t.A, t.B)

    }
}

Answer 3

Current gopkg.in/yaml.v3 Deocder produces quite correct result, you just need to pay attention on creating new structure for each document and check it was parsed correctly (with nil check), and handle EOF error correctly:

package main

import "fmt"
import "gopkg.in/yaml.v3"
import "os"
import "errors"
import "io"

type Spec struct {
    Name string `yaml:"name"`
}

func main() {
    f, err := os.Open("spec.yaml")
    if err != nil {
        panic(err)
    }
    d := yaml.NewDecoder(f)
    for {
        // create new spec here
        spec := new(Spec)
        // pass a reference to spec reference
        err := d.Decode(&spec)
        // check it was parsed
        if spec == nil {
            continue
        }
        // break the loop in case of EOF
        if errors.Is(err, io.EOF) {
            break
        }
        if err != nil {
            panic(err)
        }
        fmt.Printf("name is '%s'\n", spec.Name)
    }
}

Test file spec.yaml :

---
name: "doc first"
---
name: "second"
---
---
name: "skip 3, now 4"
---