JSON struct to csv in Go Lang - json

Question

Looking for ideas to export JSON read structs into some csv format while preserving the hierarchy.
https://play.golang.org/p/jf2DRL1hC5K
/*
Expected output in excel for data wrangling:
A Key | B Key | C Key | D Key
SomethingA SomethingB SomethingC SomethingF
SomethingA SomethingB SomethingC SomethingG
SomethingA SomethingB SomethingC [1,2,3]
*/
I have tried iterating through the struct as following
for _, value := range mymodel {
fmt.Println(value)
/* could not iterate over structs */
}

Answer 1

Adding a method to your RootModel for both header and individual rows (so you can range over the type and only print the header once):
type RootModel struct {
A string
B string
C string
D factors
}
type factors struct {
F string
G string
H []int
}
func (*RootModel) CSVheader(w io.Writer) {
cw := csv.NewWriter(w)
cw.Write([]string{"A Key", "B Key", "C Key", "D Key"})
cw.Flush()
}
func (rm *RootModel) CSVrow(w io.Writer) {
cw := csv.NewWriter(w)
cw.Write([]string{rm.A, rm.B, rm.C, rm.D.F})
cw.Write([]string{rm.A, rm.B, rm.C, rm.D.G})
is, _ := json.Marshal(rm.D.H)
cw.Write([]string{rm.A, rm.B, rm.C, string(is)})
cw.Flush()
}
Playground: https://play.golang.org/p/c8UQVQ8tQTX
Output:
A Key,B Key,C Key,D Key
SomethingA,SomethingB,SomethingC,SomethingF
SomethingA,SomethingB,SomethingC,SomethingG
SomethingA,SomethingB,SomethingC,"[1,2,3]"
Note: if you are dealing with a slice of RootModel, you may want to put the CSV writer logic at that level - so it can handle the single render of the header-row and then the subsequent data rows.