CODEWITHSUNDEEP
jsongo
lincolnge
lincolnge

Reputation: 1037

golang DeepEqual: when the type of value of interface map is array, the DeepEqual is invalidation

package main

import (
    "encoding/json"
    "fmt"
    "reflect"
)

func main() {
    nodeArray := map[string]interface{}{
        "meta": map[string]interface{}{
            "category": "paragraph"}, "content": []string{"111"}}
    // content is number as 111 or array

    b, _ := json.Marshal(&nodeArray)
    var nodeArrayTest map[string]interface{}
    json.Unmarshal(b, &nodeArrayTest)
    if !reflect.DeepEqual(nodeArray, nodeArrayTest) {
        fmt.Println("!!!! odeArray and nodeArrayTest should be equal")
    } else {
        fmt.Println("odeArray and nodeArrayTest equal")
    }
}

Why when the interface map has array(content is number as 111 or array), the return of DeepEqual is false? And when the content value is a string, a map, the DeepEqual is true.

Upvotes: 1

Views: 3824

Answers (2)

Derek
Derek

Reputation: 1

aaa := map[string]interface {}{"meta":map[string]interface {}{"category":"paragraph"}, "content":[]string{"111","222"}}
bbb := map[string]interface {}{"content":[]string{"222","111"}, "meta":map[string]interface {}{"category":"paragraph"}}

It's not true.

Upvotes: -2

James Henstridge
James Henstridge

Reputation: 43899

Printing out the two values, in question, we can see that they are different:

nodeArray = map[string]interface {}{"meta":map[string]interface {}{"category":"paragraph"}, "content":[]string{"111"}}
nodeArrayTest = map[string]interface {}{"content":[]interface {}{"111"}, "meta":map[string]interface {}{"category":"paragraph"}}

In particular, nodeArray["content"] is a []string slice, while nodeArrayTest["content"] is a a []interface{} slice. The reflect.DeepEqual function does not consider these equal due to the type mismatch.

The encoding/json module decodes into an []interface{} slice because JSON arrays can contain values of different types.

Upvotes: 3

Related Questions