GitHub - m-zajac/json2go: Create go type representation from json (original) (raw)

Package json2go provides utilities for creating go type representation from json inputs.

Json2go can be used in various ways:

Why another conversion tool?

There are few tools for converting json to go types available already. But all of which I tried worked correctly with only basic documents.

The goal of this project is to create types, that are guaranteed to properly unmarshal input data. There are multiple test cases that check marshaling/unmarshaling both ways to ensure generated type is accurate.

Here's the micro acid test if you want to check this or other conversion tools:

[{"date":"2020-10-03T15:04:05Z","text":"txt1","doc":{"x":"x"}},{"date":"2020-10-03T15:05:02Z","_doc":false,"arr":[[1,null,1.23]]},{"bool":true,"doc":{"y":123}}]

And correct output with some comments:

type Document []struct { Arr [][]*float64 json:"arr,omitempty" // Should be doubly nested array; should be a pointer type because there's null in values. Bool *bool json:"bool,omitempty" // Shouldn't be bool because when key is missing you'll get false information. Date *time.Time json:"date,omitempty" // Could be also string or *string. Doc *struct { X *string json:"x,omitempty" // Should be pointer, because key is not present in all documents. Y *int json:"y,omitempty" // Should be pointer, because key is not present in all documents. } json:"doc,omitempty" // Should be pointer, because key is not present in all documents in array. Doc2 *bool json:"_doc,omitempty" // Attribute for "_doc" key (other that for "doc"!). Type - the same as Bool attribute. Text *string json:"text,omitempty" // Could be also string. }

CLI Installation

go install github.com/m-zajac/json2go/cmd/json2go@latest

Usage

Json2go can be used as cli tool or as package.

CLI tools can be used directly to create go type from stdin data (see examples).

Package provides Parser, which can consume multiple jsons and outputs go type fitting all inputs (see examples and documentation). Example usage: read documents from document-oriented database and feed them too parser for go struct.

CLI usage examples

echo '{"x":1,"y":2}' | json2go

curl -s https://api.punkapi.com/v2/beers?page=1&per_page=5 | json2go

Check this one :)

Package usage examples

inputs := []string{ {"x": 123, "y": "test", "z": false}, {"a": 123, "x": 12.3, "y": true}, }

parser := json2go.NewJSONParser("Document") for _, in := range inputs { parser.FeedBytes([]byte(in)) }

res := parser.String() fmt.Println(res)

Example outputs

{ "line": { "point1": { "x": 12.1, "y": 2 }, "point2": { "x": 12.1, "y": 2 } } }

type Document struct { Line struct { Point1 Point json:"point1" Point2 Point json:"point2" } json:"line" } type Point struct { X float64 json:"x" Y int json:"y" }

[ { "name": "water", "type": "liquid", "boiling_point": { "units": "C", "value": 100 } }, { "name": "oxygen", "type": "gas", "density": { "units": "g/L", "value": 1.429 } }, { "name": "carbon monoxide", "type": "gas", "dangerous": true, "boiling_point": { "units": "C", "value": -191.5 }, "density": { "units": "kg/m3", "value": 789 } } ]

type Document []struct { BoilingPoint *UnitsValue json:"boiling_point,omitempty" Dangerous *bool json:"dangerous,omitempty" Density *UnitsValue json:"density,omitempty" Name string json:"name" Type string json:"type" } type UnitsValue struct { Units string json:"units" Value float64 json:"value" }

Contribution

I'd love your input! Especially reporting bugs and proposing new features.