Hey everyone I have a very simple go REST API that is running CRUD operations on an in-memory object. I would love some feedback on how I can refactor this code, and how/if I should break this up into more than one file (main.go). I am extremely new to Go and want to learn the best way to write something like this.

Some areas that I think could use improvement:

1. The way my code is handling 500s
2. JSON Request field validation feels like I am repeating it a lot
3. File structure/organization

Any help would be greatly appreciated. Below is my code:

type Trade struct {    ClientTradeId string `json:"client_trade_id" validate:"nonzero, min=1, max=256"`    Date          int    `json:"date" validate:"nonzero, min=20010101, max=21000101"`    Quantity      string `json:"quantity" validate:"regexp=^[-]?[0-9]*\\.?[0-9]+$"`    Price         string `json:"price" validate:"nonzero, regexp=^[-]?[0-9]*\\.?[0-9]+$"`    Ticker        string `json:"ticker" validate:"nonzero"`}type InternalTrade struct {    Id string `json:"Id" validate:"nonzero"`    Trade *Trade `json:"Trade"`}type TradeSubmitted struct {    TradeId string `json:"TradeId" validate:"nonzero"`    ClientTradeId string `json:"clientTradeId" validate:"nonzero"`}type Error struct {    Message string `json:"Message"`}var trades []InternalTradevar submitArray []TradeSubmittedvar (    tradeValidator = validator.NewValidator())func getTrades(w http.ResponseWriter, r *http.Request) {    w.Header().Set("Content-Type", "application/json")    err := json.NewEncoder(w).Encode(trades)    if err != nil {        e := Error{Message:"Internal Server Error"}        w.WriteHeader(http.StatusInternalServerError)        _ = json.NewEncoder(w).Encode(e)        return    }}func getTradeById(w http.ResponseWriter, r *http.Request) {    w.Header().Set("Content-Type", "application/json")    params := mux.Vars(r)    for _, trade := range trades {        if trade.Id == params["trade_id"] {            _ = json.NewEncoder(w).Encode(trade)            return        }    }    e := Error{Message: "ID Not Found"}    w.WriteHeader(http.StatusNotFound)    if err := json.NewEncoder(w).Encode(e); err != nil {        e := Error{Message:"Internal Server Error"}        http.Error(w, e.Message, http.StatusInternalServerError)    }}func createTrade(w http.ResponseWriter, r *http.Request) {    w.Header().Set("Content-Type", "application/json")    var tradeArray []Trade    if err := json.NewDecoder(r.Body).Decode(&tradeArray); err != nil {        e := Error{Message:"Not processable - Missing Required"}        w.WriteHeader(http.StatusBadRequest)        _ = json.NewEncoder(w).Encode(e)        return    }    for _, trade := range tradeArray {        th := trade        if errs := tradeValidator.Validate(&th); errs != nil {            e := Error{Message: "Bad Request - Improper Types Passed"}            w.WriteHeader(http.StatusUnprocessableEntity)            _ = json.NewEncoder(w).Encode(e)            return        }    }    for i := range tradeArray {        internal := InternalTrade{            Id:    strconv.Itoa(rand.Intn(1000000)),            Trade: &tradeArray[i],        }        submit := TradeSubmitted{            TradeId:       internal.Id,            ClientTradeId: internal.Trade.ClientTradeId,        }        submitArray = append(submitArray, submit)        trades = append(trades, internal)    }    if err := json.NewEncoder(w).Encode(submitArray); err != nil {        e := Error{Message:"Internal Server Error"}        w.WriteHeader(http.StatusInternalServerError)        _ = json.NewEncoder(w).Encode(e)        return    }}func deleteTrade(w http.ResponseWriter, r *http.Request) {    params := mux.Vars(r)    for idx, trade := range trades {        if trade.Id == params["trade_id"] {            trades = append(trades[:idx], trades[idx+1:]...)            w.WriteHeader(http.StatusNoContent)            return        }    }    e := Error{Message:"ID Not Found"}    w.WriteHeader(http.StatusNotFound)    if err := json.NewEncoder(w).Encode(e); err != nil {        e := Error{Message:"Internal Server Error"}        http.Error(w, e.Message, http.StatusInternalServerError)    }}func updateTrade(w http.ResponseWriter, r *http.Request) {    w.Header().Set("Content-Type", "application/json")    params := mux.Vars(r)    for idx, trade := range trades {        if trade.Id == params["trade_id"] {            trades = append(trades[:idx], trades[idx+1:]...)            var internal InternalTrade            _  = json.NewDecoder(r.Body).Decode(&internal.Trade)            internal.Id = params["trade_id"]            trades = append(trades, internal)            json.NewEncoder(w).Encode(internal)            return        }    }    e := Error{Message:"ID Not Found"}    w.WriteHeader(http.StatusNotFound)    if err := json.NewEncoder(w).Encode(e); err != nil {        e := Error{Message:"Internal Server Error"}        http.Error(w, e.Message, http.StatusInternalServerError)    }}func main() {    router := mux.NewRouter()    trades = append(trades, InternalTrade{ Id:"1", Trade: &Trade{ClientTradeId: "T-50264430-bc41", Date:20200101,        Quantity:"100", Price:"10.00", Ticker:"APPL"}})    trades = append(trades, InternalTrade{ Id:"2", Trade: &Trade{ClientTradeId: "T-99999999-ab14", Date:20200101,        Quantity:"100", Price:"420.00", Ticker:"TSLA"}})    router.HandleFunc("/v1/trades", getTrades).Methods("GET")    router.HandleFunc("/v1/trades/{trade_id}", getTradeById).Methods("GET")    router.HandleFunc("/v1/trades", createTrade).Methods("POST")    router.HandleFunc("/v1/trades/{trade_id}", deleteTrade).Methods("DELETE")    router.HandleFunc("/v1/trades/{trade_id}", updateTrade).Methods("PUT")    log.Fatal(http.ListenAndServe(":8080", router))}

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