A concise way to declare structs and marshal them into JSON in Go.
Making nested structs/arrays in order to marshal JSON from objects can be such a pain sometimes, can't it? Especially when you are cherry-picking fields from one flat JSON message and trying to output them into another complex JSON message.
Well, along comes hummus which makes this super-duper easy. The biggest win, I feel, is that you can have all your nesting information in the same struct. Creating nested arrays and/or objects is a simple matter of using dots (.) or square brackets ([]) in your tags.
go get github.com/aditya87/hummus
go get github.com/Jeffail/gabs
go get github.com/onsi/ginkgo/ginkgo
go get github.com/onsi/gomega
...
type Info struct {
Company string `hummus:"company"`
Address string `hummus:"address"`
Brand0Name string `hummus:"brands[0].name"`
Brand0Flavor string `hummus:"brands[0].flavor"`
Brand0Store0Name string `hummus:"brands[0].stores[0].name"`
Brand0Store0Price int `hummus:"brands[0].stores[0].price,omitempty"`
Brand0Store1Name string `hummus:"brands[0].stores[1].name"`
Brand0Store1Price int `hummus:"brands[0].stores[1].price,omitempty"`
}
func main() {
info := Info{
Company: "hello foods",
Address: "338 New St",
Brand0Name: "sabra",
Brand0Flavor: "jalapeno",
Brand0Store0Name: "safeway",
Brand0Store0Price: 5,
Brand0Store1Name: "wholefoods",
Brand0Store1Price: 10,
}
jsonOutput, err := hummus.Marshal(info)
if err != nil {
panic(err)
}
fmt.Println(string(jsonOutput))
}
Gives us:
{
"company": "hello foods",
"address": "338 New St",
"brands": [
{
"flavor": "jalapeno",
"name": "sabra",
"stores": [
{
"name": "safeway",
"price": 5
},
{
"name": "wholefoods",
"price": 10
}
]
}
]
}
type Info struct {
Name string `json:"name" hummus:"name"`
Flavor string `json:"flavor" hummus:"type"`
MainSupplierName string `json:"main_supplier_name" hummus:"suppliers[0].name"`
MainSupplierLocation string `json:"main_supplier_location" hummus:"suppliers[0].location"`
BackupSupplierName string `json:"backup_supplier_name" hummus:"suppliers[1].name"`
BackupSupplierLocation string `json:"backup_supplier_location" hummus:"suppliers[1].location"`
}
func main() {
inputJSON := `{
"name": "sabra",
"flavor": "jalapeno",
"main_supplier_name": "Hipster Foods",
"main_supplier_location": "CO",
"backup_supplier_name": "Good Foods",
"backup_supplier_location": "CA"
}`
var input Info
err := json.Unmarshal([]byte(inputJSON), &input)
if err != nil {
panic(err)
}
jsonOutput, err := hummus.Marshal(input)
if err != nil {
panic(err)
}
fmt.Println(string(jsonOutput))
}
Gives us:
{
"name": "sabra",
"type": "jalapeno",
"suppliers": [
{
"location": "CO",
"name": "Hipster Foods"
},
{
"location": "CA",
"name": "Good Foods"
}
]
}
Sometimes, you want to not interpret the dots in a JSON tag as hierarchical keys, instead you just want them to get interpreted as a flat key like so:
{
"properties.name": "value"
}
Hummus offers you the ability to escape dots. Simply replace dots with hashtags in the struct tags:
...
type S struct {
V string `hummus:"properties#name"`
}
func main() {
s := S{
V: "value",
}
jsonOutput, err := hummus.Marshal(s)
if err != nil {
panic(err)
}
fmt.Println(string(jsonOutput))
}
This gives us:
{
"properties.name": "value"
}
Which is the desired result.
- Also provided an
omitemptyoption to ignore empty fields, just like the encoding/json library. e.g.:
type foo struct {
bar string `hummus:"bar,omitempty"`
}
PRs are welcome. Make sure unit tests are run. To do so, firstly install the ginkgo and gomega libraries as described in the "fetch dependencies" section above. Then, simply run:
ginkgo -r .
In the main directory.
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