json v2 omit zero behavior #22

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1. lpic10 commented on Sep 2, 2025

   

   lpic10

   on Sep 2, 2025

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   Updated, we need to set OmitEmptyWithLegacySemantics, as the OmitZeroStructFields will have unintended effects, see below

   package main
   
   import (
           "encoding/json"
           "fmt"
   
           jsonv2 "encoding/json/v2"
   
           "github.com/oapi-codegen/nullable"
   )
   
   type InnerStruct struct {
           AnotherValue string
   }
   
   type TestStruct struct {
           Name             string                                    `json:"name"`
           Bool             bool                                      `json:"bool"`
           ValueInt         nullable.Nullable[int]                    `json:"valueInt,omitempty"`
           ValueString      nullable.Nullable[string]                 `json:"valueString,omitempty"`
           ValueStruct      nullable.Nullable[InnerStruct]            `json:"valueStruct,omitempty"`
           ValueMap         nullable.Nullable[map[string]string]      `json:"valueMap,omitempty"`
           ValueMapStruct   nullable.Nullable[map[string]InnerStruct] `json:"valueMapStruct,omitempty"`
           ValueSliceInt    nullable.Nullable[[]int]                  `json:"valueSliceInt,omitempty"`
           ValueSliceString nullable.Nullable[[]string]               `json:"valueSliceString,omitempty"`
           ValueSliceStruct nullable.Nullable[[]InnerStruct]          `json:"valueSliceStruct,omitempty"`
   }
   
   func main() {
           var testStruct TestStruct
   
           testStruct.Name = "test struct"
   
           buf, _ := json.Marshal(&testStruct)
           buf2, _ := jsonv2.Marshal(&testStruct)
           buf3, _ := jsonv2.Marshal(&testStruct, jsonv2.OmitZeroStructFields(true))
           buf4, _ := jsonv2.Marshal(&testStruct, json.OmitEmptyWithLegacySemantics(true))
   
           fmt.Println(string(buf))
           fmt.Println(string(buf2))
           fmt.Println(string(buf3))
           fmt.Println(string(buf4))
   }
   

   GOEXPERIMENT=jsonv2 go run jsontest.go
   
   {"name":"test struct","bool":false}
   {"name":"test struct","bool":false,"valueInt":0,"valueStruct":{"AnotherValue":""}}
   {"name":"test struct"}
   {"name":"test struct","bool":false}