[BUG] [Go] Json Unmarshal int bigger then int64

[dlnilsson]

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• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
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• What's the actual output vs expected output?
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Description

in the go generator, trying to unMarshal big int values, get overflow on int64

package main

import (
	"encoding/json"
	"fmt"

	"github.com/danijeel/bigintexample/openapi"
)

func main() {
	jsonSrc := []byte(`{
		"id": 162259276829213363391578010288126,
		"name": "test"
	}`)
	var myJson openapi.Category
	json.Unmarshal(jsonSrc, &myJson)
	fmt.Printf("%d\n", myJson.Id)
	// output: 824634459072
	// expects: 162259276829213363391578010288126
}

Full example can be seen here: https://github.com/danijeel/bigintexample/blob/main/main.go

openapi-generator version

5.2.1

OpenAPI declaration file content or url

The openapi example specification is based on the petstore example
https://github.com/danijeel/bigintexample/blob/eb590428c496e152ec32ff30a6464b2849b74a7b/openapi.yml

Generation Details

Steps to reproduce

Related issues/PRs

Suggest a fix

In the branch patch-big-int
I replaced the int64 attribute with custom type BigInt in the category model

dlnilsson/bigintexample@97dde59

[wing328]

Got 404 when accessing dlnilsson/bigintexample@97dde59

[dlnilsson]

Sorry, I had forgotten to make the repository public. It should work now

[wing328]

Some other generators support BigDecimal via

type: string
format: decimal

For your case, I wonder if we can do something like

type:string
format: big-int

so as to support big integer via type mappings.