Optional array in struct-CodePudding

I want to make an array optional in struct and use it with an if else in a func.

type TestValues struct {
    Test1 string `json:"test1"`
    DefaultTests []string `json:"__tests"`

    //DefaultTests *array `json:"__tests,omitempty" validate:"option"`
    Test2 string `json:"__Test2"`
}

func (x *Controller) createTest(context *gin.Context, uniqueId string, testBody *TestValues) (*http.Response, error) {

    if testBody.DefaultTags {
        postBody, err := json.Marshal(map[string]string{
            "Test2":              testBody.Test2,
            "Test1":                  testBody.Test1,
            "defaultTests":         testBody.DefaultTests,
            "uniqueId":                  uniqueId,
        })
    } else {
        postBody, err := json.Marshal(map[string]string{
            "Test2":              testBody.Test2,
            "Test1":                  testBody.Test1,
            "uniqueId":                  uniqueId,
        })
    }

    ...
}

When I run the code it tells me that DefaultTests is undefined array but I don't want this error to pop because DefaultTests can existe and sometimes it won't be present in the json that's why I want to make it optional. The if else part is not working too.

CodePudding user response：

It's better to use len() when checking if an array is empty here.

if len(testBody.DefaultTests) > 0 {
  ...
}

Check the Zero value of the DefaultTests in struct below for more clarity on this behaviour

package main

import "fmt"

type TestValues struct {
    Test1        string   `json:"test1"`
    DefaultTests []string `json:"__tests"`

    //DefaultTests *array `json:"__tests,omitempty" validate:"option"`
    Test2 string `json:"__Test2"`
}

func main() {
    var tv = TestValues{Test1: "test"}

    if len(tv.DefaultTests) > 0 {
        fmt.Printf("Default Tests: %v\n", tv.DefaultTests)
    } else {
        fmt.Printf("Default Tests empty value: %v\n", tv.DefaultTests)
    }
}

CodePudding user response：

Here's my final code with Marc's answer

func (x *Controller) createTest(context *gin.Context, uniqueId string, testBody *TestValues) (*http.Response, error) {

if len(testBody.DefaultTags) > 0 {
  postBody, err := json.Marshal(testBody.DefaultTags)

} else {
    postBody, err := json.Marshal(map[string]string{
        "Test2":              testBody.Test2,
        "Test1":                  testBody.Test1,
        "uniqueId":                  uniqueId,
    })
}

...

}