go-struct-generator

NodeJS script that outputs valid golang structs from arbitrary JSON object strings.

Create a new file named <your_struct_name>.json in the json_objects/ directory for each json string you'd like to convert:

json_objects/randomJson.json:

{
    "clientIp": "10.74.68.23",
    "uri": "/v2/apps",
    "appDefinition": {
        "id": "/nitrotest",
        "instances": 2,
        "cpus": 0.25,
        "mem": 512,
        "disk": 0,
        "ports": [0],
        "requirePorts": false,
        "backoffSeconds": 1,
        "backoffFactor": 1.15,
        "maxLaunchDelaySeconds": 3600,
        "container": {
            "type": "DOCKER",
            "docker": {
                "image": "docker-registry.com/nitrogen:blue",
                "network": "BRIDGE",
                "portMappings": [{
                    "containerPort": 0,
                    "hostPort": 31003,
                    "servicePort": 0,
                    "protocol": "tcp"
                }],
                "privileged": false,
                "forcePullImage": true
            }
        },
        "healthChecks": [{
            "path": "/healthcheck",
            "protocol": "HTTP",
            "portIndex": 0,
            "gracePeriodSeconds": 15,
            "intervalSeconds": 20,
            "timeoutSeconds": 20,
            "maxConsecutiveFailures": 3,
            "ignoreHttp1xx": false
        }],
        "upgradeStrategy": {
            "minimumHealthCapacity": 0.5,
            "maximumOverCapacity": 0.5
        },
        "version": "2016-04-01T16:48:04.485Z"
    },
    "eventType": "api_post_event",
    "timestamp": "2016-04-01T16:48:04.546Z"
}

Run node go-struct-generator.js and capture the output from the command line, or pipe directly into a golang file (node go-struct-generator.js >> myStructs.go):

type RandomJson struct {
	ClientIp string `json:"clientIp"`
	Uri string `json:"uri"`
	AppDefinition AppDefinitionStruct  `json:"appDefinition"`
	EventType string `json:"eventType"`
	Timestamp string `json:"timestamp"`
}
type PortMappingsStruct struct {
	ContainerPort float64 `json:"containerPort"`
	HostPort float64 `json:"hostPort"`
	ServicePort float64 `json:"servicePort"`
	Protocol string `json:"protocol"`
}
type DockerStruct struct {
	Image string `json:"image"`
	Network string `json:"network"`
	PortMappings []PortMappingsStruct `json:"portMappings"`
	Privileged boolean `json:"privileged"`
	ForcePullImage boolean `json:"forcePullImage"`
}
type ContainerStruct struct {
	Type string `json:"type"`
	Docker DockerStruct  `json:"docker"`
}
type HealthChecksStruct struct {
	Path string `json:"path"`
	Protocol string `json:"protocol"`
	PortIndex float64 `json:"portIndex"`
	GracePeriodSeconds float64 `json:"gracePeriodSeconds"`
	IntervalSeconds float64 `json:"intervalSeconds"`
	TimeoutSeconds float64 `json:"timeoutSeconds"`
	MaxConsecutiveFailures float64 `json:"maxConsecutiveFailures"`
	IgnoreHttp1xx boolean `json:"ignoreHttp1xx"`
}
type UpgradeStrategyStruct struct {
	MinimumHealthCapacity float64 `json:"minimumHealthCapacity"`
	MaximumOverCapacity float64 `json:"maximumOverCapacity"`
}
type AppDefinitionStruct struct {
	Id string `json:"id"`
	Instances float64 `json:"instances"`
	Cpus float64 `json:"cpus"`
	Mem float64 `json:"mem"`
	Disk float64 `json:"disk"`
	Ports []float64 `json:"ports"`
	RequirePorts boolean `json:"requirePorts"`
	BackoffSeconds float64 `json:"backoffSeconds"`
	BackoffFactor float64 `json:"backoffFactor"`
	MaxLaunchDelaySeconds float64 `json:"maxLaunchDelaySeconds"`
	Container ContainerStruct  `json:"container"`
	HealthChecks []HealthChecksStruct `json:"healthChecks"`
	UpgradeStrategy UpgradeStrategyStruct  `json:"upgradeStrategy"`
	Version string `json:"version"`
}

The script can generate valid golang structs for nearly any valid JSON object, with a few constraints:

1. Arrays must contain only elements of the same type. For example, "myIntArray": [0,1,2] or "myStringArray": ["one","two","three"], but not "myMixedArray": [1, "two", 3]. This rule applies to arrays of objects as well.

2. All numbers are cast to the golang primitive float64.

3. Empty properties will result in empty structs. For example. "myEmptyProperty":{} will generate:

   type MyEmptyPropertyStruct struct {
   }
   

   This behavior may or may not be useful to you.

Also included is a little golang script for validating the output of the go-struct-generator. Just replace the included structs with your own output, replace the value of the raw string jsontest with the json string you are attempting to convert, and run go run GoTester.go. The script will attempt to Unmarshal the json string into the generated structs, and then Marshal the results back into a json object.

Tested using Node version v0.12.7, results with other versions may vary.