Hey there just started to transform my python code to Go, but have some issue on the json manipulations... here is my code so far

import (
    "encoding/json"
    "fmt"
    "io/ioutil"
    "net/http"
    "strings"
)

type Collection struct {
    Contract string
}

type Data struct {
    Activity Activity `json:"activity"`
}

type Activity struct {
    Activities Activities `json:"activities"`
    HasMore    bool       `json:"hasMore"`
}

type Activities struct {
    Sale []Sale `json:"sale"`
}

type Sale struct {
    From             string           `json:"from"`
    From_login       string           `json:"from_login"`
    To               string           `json:"to"`
    To_login         string           `json:"to_login"`
    Transaction_hash string           `json:"transaction_hash"`
    Timestamp        int              `json:"timestamp"`
    Types            string           `json:"type"`
    Price            float32          `json:"price"`
    Quantity         string           `json:"quantity"`
    Nft              Nft              `json:"nft"`
    Attributes       string           `json:"attributes"`
    Collection       CollectionStruct `json:"collection"`
}

type Nft struct {
    Name       string        `json:"name"`
    Thumbnail  string        `json:"thumbnail"`
    Asset_id   string        `json:"asset_id"`
    Collection NftCollection `json:"collection"`
}

type NftCollection struct {
    Avatar    string `json:"avatar"`
    Name      string `json:"name"`
    Certified bool   `json:"certified"`
}

type CollectionStruct struct {
    Avatar    string `json:"avatar"`
    Address   string `json:"address"`
    Name      string `json:"name"`
    Certified bool   `json:"certified"`
}

func (c Collection) GetSales(filter, types string) string { // déclaration de ma méthode GetSales() liée à ma structure Collection
    const url = "https://api.com/"

    // create a new request using http
    req, err := http.NewRequest("POST", url, requestBody)
    if err != nil {
        panic(err)
    }

    defer res.Body.Close()
    content, _ := ioutil.ReadAll(res.Body)

    var resultJson Data
    json.Unmarshal([]byte(content), &resultJson)
    fmt.Printf("% v\n", resultJson)

i don't understand why my Sale structure is empty :/ I created all of these structures in order to use Unmarshal so i can loop. I check the way the returned json is structured and copied it i'm sure i missed something but don't know what

CodePudding user response：

Your code as written won't compile (due to a couple of undefined variables), so it's hard to separate functional problems from syntactic problems.

However, one thing stands out: You're creating an HTTP request with req, err := http.NewRequest(...), but you're never executing the request with a client. See e.g. the documentation, which includes this example:

client := &http.Client{
    CheckRedirect: redirectPolicyFunc,
}

resp, err := client.Get("http://example.com")
// ...

req, err := http.NewRequest("GET", "http://example.com", nil)
// ...
req.Header.Add("If-None-Match", `W/"wyzzy"`)
resp, err := client.Do(req)
// ...

If you use NewRequest to create a request, you must use client.Do(req) to execute it.

CodePudding user response：

Adding to @larsks 's answer, there are more errors that I can see

1. ioutil.ReadAll already returns a byte array which you can directly use for un-marshalling. json.Unmarshal(content, &resultJson)

2. Many errors are ignored so execution won't stop if any error is encountered.

I suggest changing the function as follows:

func (c Collection) GetSales(filter, types string) []Sale {
    const url = "https://api.com/"

    req, err := http.NewRequest("POST", url, requestBody)
    if err != nil {
        panic(err)
    }
    
    res, err := http.DefaultClient.Do(req)
    if err != nil {
        panic(err)
    }

    defer res.Body.Close()
    content, err := ioutil.ReadAll(res.Body)
    if err != nil {
        panic(err)
    }

    var resultJson Data
    err = json.Unmarshal(content, &resultJson)
    if err != nil {
        panic(err)
    }

    fmt.Printf("% v\n", resultJson)
    return resultJson.Activity.Activities.Sales
}