This is my definition dto class:
using System;
using System.Text.Json;
using System.Text.Json.Serialization;
namespace DeserializeDemo
{
public class SubTaskRuleDto
{
public Guid Id { get; set; }
[JsonConverter(typeof(ByteArrayConverter))]
public byte[] Content { get; set; }
public bool DisableImage { get; set; }
public bool UseMobileAgent { get; set; }
public bool SupplementEnable { get; set; }
}
public class ByteArrayConverter : JsonConverter<byte[]>
{
public override byte[] Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
{
short[] sByteArray = JsonSerializer.Deserialize<short[]>(ref reader);
byte[] value = new byte[sByteArray.Length];
for (int i = 0; i < sByteArray.Length; i++)
{
value[i] = (byte)sByteArray[i];
}
return value;
}
public override void Write(Utf8JsonWriter writer, byte[] value, JsonSerializerOptions options)
{
writer.WriteStartArray();
foreach (var val in value)
{
writer.WriteNumberValue(val);
}
writer.WriteEndArray();
}
}
}
Then I Will show the asp.net core Controller code:
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
using System;
namespace DeserializeDemo.Controllers
{
[ApiController]
[Route("[controller]")]
public class Clouds : ControllerBase
{
private readonly ILogger<Clouds> _logger;
public Clouds(ILogger<Clouds> logger)
{
_logger = logger;
}
[HttpGet]
public SubTaskRuleDto Get()
{
return new SubTaskRuleDto()
{
Id = Guid.NewGuid(),
Content = new byte[] { 1, 7},
DisableImage = false,
UseMobileAgent = true,
SupplementEnable = false,
};
}
public enum ContentType
{
Xoml = 1,
Python = 7,
NodeJS = 8
}
}
}
The api works well, and test ok in postman:
enter image description here
When I call the api in my python client, my code just like this:
# -*- coding:utf-8 -*-
import json
import deserialize
import requests
class SubTaskRuleRes:
id: str
content: str
disableImage: bool
useMobileAgent: bool
supplementEnable: bool
def get_subtask_rule():
url = "http://localhost:5000/clouds"
res = requests.get(url)
# print(res.content)
# binary = res.content
# output = json.loads(binary)
my_instance = deserialize.deserialize(SubTaskRuleRes, res.json())
print(my_instance)
get_subtask_rule()
deserialize- 1.8.3 - https://github.com/dalemyers/deserialize
The problem is I Cannot deserialize a list to '<class 'str'>' or a list for SubTaskRuleRes.content.
deserialize does not perform implicit type conversion. That is the reason for the error you get (note, always post the full traceback you get).
Looking at the docs, you can use decorator to pass a parser function (look at Advanced Usage/Parsers, e.g.
import deserialize
#deserialize.parser("content", str)
class SubTaskRuleRes:
id: str
content: str
disableImage: bool
useMobileAgent: bool
supplementEnable: bool
def get_subtask_rule():
spam = {'id':'28631ee-abd', 'content':[1, 7],
'disableImage': False, 'useMobileAgent':True,
'supplementEnable': False}
return deserialize.deserialize(SubTaskRuleRes, spam)
rule = get_subtask_rule()
print(rule.content)
print(type(rule.content))
output
[1, 7]
<class 'str'>
Note, I am not sure why would you want content to be list literal, string
I am making a a roulette REST API in Golang:
package main
import (
"fmt"
"io/ioutil"
"log"
"net/http"
"github.com/gorilla/mux"
)
func handleRequests() {
// creates a new instance of a mux router
myRouter := mux.NewRouter().StrictSlash(true)
myRouter.HandleFunc("/spin/", handler).Methods("POST")
log.Fatal(http.ListenAndServe(":10000", myRouter))
}
func handler(w http.ResponseWriter, r *http.Request) {
reqBody, _ := ioutil.ReadAll(r.Body)
s := string(reqBody)
fmt.Println(s)
}
func main() {
fmt.Println("Rest API v2.0 - Mux Routers")
handleRequests()
}
main.go
And I am testing the POST method with a Python script:
import requests
url = 'http://localhost:10000/spin/'
myobj = {'bets':[
{
'amount' : 10,
'position' : [0,1,2]
},
{
'amount' : 20,
'position' : [10]
}
]
}
x = requests.post(url, data = myobj)
print(x.text)
test.py
When I run the test script. And the server receives my POST request. The request body is:
bets=amount&bets=position&bets=amount&bets=position
The problem is that the values for the 'amount' and 'position' keys are not there.
My question is - how can I make/ handle POST requests so that I am able to access the values for the embedded keys 'amount' and 'position' in my handler function on the Go server, so that I can put this information into an instance of a struct.
The problem lies on the python side, if you print out the body/header of your request:
print requests.Request('POST', url, data=myobj).prepare().body
print requests.Request('POST', url, data=myobj).prepare().headers
# bets=position&bets=amount&bets=position&bets=amount
# {'Content-Length': '51', 'Content-Type': 'application/x-www-form-urlencoded'}
data uses x-www-form-urlencoded encoding, so expects a flat list of key/value pairs.
You probably want json to represent your data:
print requests.Request('POST', url, json=myobj).prepare().body
print requests.Request('POST', url, json=myobj).prepare().headers
# {"bets": [{"position": [0, 1, 2], "amount": 10}, {"position": [10], "amount": 20}]}
# {'Content-Length': '83', 'Content-Type': 'application/json'}
Fix:
x = requests.post(url, json = myobj) // `json` not `data`
Finally, it's worth checking the Content-Type header on the Go server-side to ensure you get the encoding you expect (in this case application/json).
I think you need a struct to unmarshal the data.I think this code could help you.
package main
import (
"encoding/json"
"fmt"
"github.com/gorilla/mux"
"io/ioutil"
"log"
"net/http"
)
type Body struct {
Bets []Persion `json:"bets"`
}
type Persion struct{
Amount int `json:"amount"`
Position []int `json:"position"`
}
func handleRequests() {
// creates a new instance of a mux router
myRouter := mux.NewRouter().StrictSlash(true)
myRouter.HandleFunc("/spin/", handler).Methods("POST")
log.Fatal(http.ListenAndServe(":10000", myRouter))
}
func handler(w http.ResponseWriter, r *http.Request) {
reqBody, _ := ioutil.ReadAll(r.Body)
bodyObj :=&Body{}
err:=json.Unmarshal(reqBody,bodyObj)
if err!=nil{
log.Println("%s",err.Error())
}
//s := string(reqBody)
fmt.Println(bodyObj.Bets[0].Amount)
}
func main() {
fmt.Println("Rest API v2.0 - Mux Routers")
handleRequests()
}
This question already has answers here:
Reactjs, Super expression must either be null or a function
(2 answers)
Closed 5 years ago.
So I'm new to React and even though I've found multiple others having the same issue, I still haven't found the error in my code. Therefore I turn to you stackoverflow, you're my only hope!
I am learning, so I wanted to create a simple ReactJS application that handles a HTTP-request. After finishing the code I encountered the error:
Uncaught TypeError: Super expression must either be null or a function, not object
at exports.default (inherits.js?0578:21)
at eval (app.js?71f7:22)
The error persists even though I've tried a lot of different changes and I am fairly certain that it's related to imports/exports as this is what a lot of other sources tell me, although double-checking imports etc. hasn't yielded any results.
The code:
app.js ( handles the rendering of a simple button and should execute a simple GET request on click )
import React, { Component } from 'react'
import { connect } from 'react-redux'
import { createServerSagaRequest } from '../saga/serverSaga'
import { incrRequestAmount, requestSelector } from '../reducer/requestReducer'
const mapStateToProps = (state) => {
return {
getRequestAmount: requestSelector.requests(state),
}
}
const mapDispatchToProps = (dispatch) => {
return {
open: (url, data, action, method) => dispatch(createServerSagaRequest((url, data, action, method))),
requests: () => dispatch(incrRequestAmount()),
}
}
class App extends React {
constructor(props){
super(props)
}
_buttonClick() {
this.props.requests()
this.props.open("http://mvctestproject.local/GetData", "TestDataFraGet", action, "GET")
}
render(){
return (
<button
className="btn btn-default"
onClick={this._buttonClick()}>{this.props.getRequestAmount()}
</button>
)
}
}
export default connect(mapStateToProps, mapDispatchToProps)(App)
serverSaga.js (my saga which can access the reducer and service)
import React, { Component } from 'react'
import { put, call, take, fork, select } from 'redux-saga/effects'
import { callServer } from '../service/serverService'
import { incrRequestAmount, requestSelector } from '../reducer/requestReducer'
export function createServerSagaRequest() {return { type: CREATE_REQUEST }}
function* handleRequest(url, data, action, method, success){
incrRequestAmount()
return yield executeRequest(url, data, action, method, success)
}
function* executeRequest(url, data, action, method, success) {
let response = yield call(callServer, url, method, data)
let responseSuccess = response && response.Succeeded
return
}
export default function* serverSaga(){
yield [
fork(function*(){
yield call (CREATE_REQUEST, handleRequest)
}),
]
}
rootSaga.js ( grouping sagas - in case I made more )
import { fork } from 'redux-saga/effects'
import serverSaga from './serverSaga'
export default function* rootSaga(){
yield [
fork(serverSaga)
]
}
requestReducer.js ( only function is to increment a variable after each request)
import { fromJS } from 'immutable'
export function incrRequestAmount() {return {type: 'INCR_REQUESTS'}}
const initialState = {
requestAmount: 0
}
function requestReducer(state = fromJS(initialState), action){
switch(action.type){
case 'INCR_REQUESTS':
return state.updateIn(["requestAmount"], (requests) => requests++)
default:
return state
}
}
export const requestSelector = {
amount: state => state.requests.get('requestAmount')
}
export default requestReducer
reducers.js ( grouping reducers - in case i made more )
import { combineReducers } from 'redux'
import React, { Component } from 'react'
import requests from './requestReducer'
export default combineReducers({
requests,
})
serverService.js ( handles calls to the server (GET/POST)
import React, { Component } from 'react'
export function callServer(url, bodyData, method){
let methodType = method.toLowerCase()
return new Promise((resolve, reject) => {
let r;
switch (methodType){
case 'post':
r = {
method: 'POST',
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json',
},
body: JSON.stringify(bodyData)
}
break;
case 'get':
r = {
method: 'GET'
}
break;
}
if (r) {
console.log("URL: ", url)
fetch(url, r)
.then((response) => {
console.log("Resp: ", url, response)
return response.json()
})
}
})
}
You need to extend React.Component to create a component, not React itself:
class App extends React {
should be
class App extends React.Component {
, or since you imported Component directly
class App extends Component {
Given a string of JSON data, how can I safely turn that string into a JavaScript object?
Obviously I can do this unsafely with something like:
var obj = eval("(" + json + ')');
but that leaves me vulnerable to the JSON string containing other code, which it seems very dangerous to simply eval.
JSON.parse(jsonString) is a pure JavaScript approach so long as you can guarantee a reasonably modern browser.
The jQuery method is now deprecated. Use this method instead:
let jsonObject = JSON.parse(jsonString);
Original answer using deprecated jQuery functionality:
If you're using jQuery just use:
jQuery.parseJSON( jsonString );
It's exactly what you're looking for (see the jQuery documentation).
This answer is for IE < 7, for modern browsers check Jonathan's answer above.
This answer is outdated and Jonathan's answer above (JSON.parse(jsonString)) is now the best answer.
JSON.org has JSON parsers for many languages including four different ones for JavaScript. I believe most people would consider json2.js their goto implementation.
Use the simple code example in "JSON.parse()":
var jsontext = '{"firstname":"Jesper","surname":"Aaberg","phone":["555-0100","555-0120"]}';
var contact = JSON.parse(jsontext);
and reversing it:
var str = JSON.stringify(arr);
This seems to be the issue:
An input that is received via Ajax websocket etc, and it will be in String format, but you need to know if it is JSON.parsable. The touble is, if you always run it through JSON.parse, the program MAY continue "successfully" but you'll still see an error thrown in the console with the dreaded "Error: unexpected token 'x'".
var data;
try {
data = JSON.parse(jqxhr.responseText);
} catch (_error) {}
data || (data = {
message: 'Server error, please retry'
});
I'm not sure about other ways to do it but here's how you do it in Prototype (JSON tutorial).
new Ajax.Request('/some_url', {
method:'get',
requestHeaders: {Accept: 'application/json'},
onSuccess: function(transport){
var json = transport.responseText.evalJSON(true);
}
});
Calling evalJSON() with true as the argument sanitizes the incoming string.
If you're using jQuery, you can also use:
$.getJSON(url, function(data) { });
Then you can do things like
data.key1.something
data.key1.something_else
etc.
Just for fun, here is a way using a function:
jsonObject = (new Function('return ' + jsonFormatData))()
$.ajax({
url: url,
dataType: 'json',
data: data,
success: callback
});
The callback is passed the returned data, which will be a JavaScript object or array as defined by the JSON structure and parsed using the $.parseJSON() method.
Using JSON.parse is probably the best way.
Here's an example
var jsonRes = '{ "students" : [' +
'{ "firstName":"Michel" , "lastName":"John" ,"age":18},' +
'{ "firstName":"Richard" , "lastName":"Joe","age":20 },' +
'{ "firstName":"James" , "lastName":"Henry","age":15 } ]}';
var studentObject = JSON.parse(jsonRes);
The easiest way using parse() method:
var response = '{"result":true,"count":1}';
var JsonObject= JSON.parse(response);
Then you can get the values of the JSON elements, for example:
var myResponseResult = JsonObject.result;
var myResponseCount = JsonObject.count;
Using jQuery as described in the jQuery.parseJSON() documentation:
JSON.parse(jsonString);
Try using the method with this Data object. ex:Data='{result:true,count:1}'
try {
eval('var obj=' + Data);
console.log(obj.count);
}
catch(e) {
console.log(e.message);
}
This method really helps in Nodejs when you are working with serial port programming
I found a "better" way:
In CoffeeScript:
try data = JSON.parse(jqxhr.responseText)
data ||= { message: 'Server error, please retry' }
In Javascript:
var data;
try {
data = JSON.parse(jqxhr.responseText);
} catch (_error) {}
data || (data = {
message: 'Server error, please retry'
});
JSON parsing is always a pain. If the input is not as expected it throws an error and crashes what you are doing.
You can use the following tiny function to safely parse your input. It always turns an object even if the input is not valid or is already an object which is better for most cases:
JSON.safeParse = function (input, def) {
// Convert null to empty object
if (!input) {
return def || {};
} else if (Object.prototype.toString.call(input) === '[object Object]') {
return input;
}
try {
return JSON.parse(input);
} catch (e) {
return def || {};
}
};
Parse the JSON string with JSON.parse(), and the data becomes a JavaScript object:
JSON.parse(jsonString)
Here, JSON represents to process JSON dataset.
Imagine we received this text from a web server:
'{ "name":"John", "age":30, "city":"New York"}'
To parse into a JSON object:
var obj = JSON.parse('{ "name":"John", "age":30, "city":"New York"}');
Here obj is the respective JSON object which looks like:
{ "name":"John", "age":30, "city":"New York"}
To fetch a value use the . operator:
obj.name // John
obj.age //30
Convert a JavaScript object into a string with JSON.stringify().
JSON.parse(jsonString);
json.parse will change into object.
JSON.parse() converts any JSON string passed into the function into a JSON object.
To understand it better, press F12 to open "Inspect Element" in your browser and go to the console to write the following commands:
var response = '{"result":true,"count":1}'; //sample json object(string form)
JSON.parse(response); //converts passed string to JSON Object.
Now run the command:
console.log(JSON.parse(response));
You'll get output as an Object {result: true, count: 1}.
In order to use that Object, you can assign it to the variable, maybe obj:
var obj = JSON.parse(response);
By using obj and the dot (.) operator you can access properties of the JSON object.
Try to run the command:
console.log(obj.result);
Official documentation:
The JSON.parse() method parses a JSON string, constructing the JavaScript value or object described by the string. An optional reviver function can be provided to perform a transformation on the resulting object before it is returned.
Syntax:
JSON.parse(text[, reviver])
Parameters:
text
: The string to parse as JSON. See the JSON object for a description of JSON syntax.
reviver (optional)
: If a function, this prescribes how the value originally produced by parsing is transformed, before being returned.
Return value
The Object corresponding to the given JSON text.
Exceptions
Throws a SyntaxError exception if the string to parse is not valid JSON.
If we have a string like this:
"{\"status\":1,\"token\":\"65b4352b2dfc4957a09add0ce5714059\"}"
then we can simply use JSON.parse twice to convert this string to a JSON object:
var sampleString = "{\"status\":1,\"token\":\"65b4352b2dfc4957a09add0ce5714059\"}"
var jsonString= JSON.parse(sampleString)
var jsonObject= JSON.parse(jsonString)
And we can extract values from the JSON object using:
// instead of last JSON.parse:
var { status, token } = JSON.parse(jsonString);
The result will be:
status = 1 and token = 65b4352b2dfc4957a09add0ce5714059
Performance
There are already good answer for this question, but I was curious about performance and today 2020.09.21 I conduct tests on MacOs HighSierra 10.13.6 on Chrome v85, Safari v13.1.2 and Firefox v80 for chosen solutions.
Results
eval/Function (A,B,C) approach is fast on Chrome (but for big-deep object N=1000 they crash: "maximum stack call exceed)
eval (A) is fast/medium fast on all browsers
JSON.parse (D,E) are fastest on Safari and Firefox
Details
I perform 4 tests cases:
for small shallow object HERE
for small deep object HERE
for big shallow object HERE
for big deep object HERE
Object used in above tests came from HERE
let obj_ShallowSmall = {
field0: false,
field1: true,
field2: 1,
field3: 0,
field4: null,
field5: [],
field6: {},
field7: "text7",
field8: "text8",
}
let obj_DeepSmall = {
level0: {
level1: {
level2: {
level3: {
level4: {
level5: {
level6: {
level7: {
level8: {
level9: [[[[[[[[[['abc']]]]]]]]]],
}}}}}}}}},
};
let obj_ShallowBig = Array(1000).fill(0).reduce((a,c,i) => (a['field'+i]=getField(i),a) ,{});
let obj_DeepBig = genDeepObject(1000);
// ------------------
// Show objects
// ------------------
console.log('obj_ShallowSmall:',JSON.stringify(obj_ShallowSmall));
console.log('obj_DeepSmall:',JSON.stringify(obj_DeepSmall));
console.log('obj_ShallowBig:',JSON.stringify(obj_ShallowBig));
console.log('obj_DeepBig:',JSON.stringify(obj_DeepBig));
// ------------------
// HELPERS
// ------------------
function getField(k) {
let i=k%10;
if(i==0) return false;
if(i==1) return true;
if(i==2) return k;
if(i==3) return 0;
if(i==4) return null;
if(i==5) return [];
if(i==6) return {};
if(i>=7) return "text"+k;
}
function genDeepObject(N) {
// generate: {level0:{level1:{...levelN: {end:[[[...N-times...['abc']...]]] }}}...}}}
let obj={};
let o=obj;
let arr = [];
let a=arr;
for(let i=0; i<N; i++) {
o['level'+i]={};
o=o['level'+i];
let aa=[];
a.push(aa);
a=aa;
}
a[0]='abc';
o['end']=arr;
return obj;
}
Below snippet presents chosen solutions
// src: https://stackoverflow.com/q/45015/860099
function A(json) {
return eval("(" + json + ')');
}
// https://stackoverflow.com/a/26377600/860099
function B(json) {
return (new Function('return ('+json+')'))()
}
// improved https://stackoverflow.com/a/26377600/860099
function C(json) {
return Function('return ('+json+')')()
}
// src: https://stackoverflow.com/a/5686237/860099
function D(json) {
return JSON.parse(json);
}
// src: https://stackoverflow.com/a/233630/860099
function E(json) {
return $.parseJSON(json)
}
// --------------------
// TEST
// --------------------
let json = '{"a":"abc","b":"123","d":[1,2,3],"e":{"a":1,"b":2,"c":3}}';
[A,B,C,D,E].map(f=> {
console.log(
f.name + ' ' + JSON.stringify(f(json))
)})
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
This shippet only presents functions used in performance tests - it not perform tests itself!
And here are example results for chrome
Converting the object to JSON, and then parsing it, works for me, like:
JSON.parse(JSON.stringify(object))
The recommended approach to parse JSON in JavaScript is to use JSON.parse()
Background
The JSON API was introduced with ECMAScript 5 and has since been implemented in >99% of browsers by market share.
jQuery once had a $.parseJSON() function, but it was deprecated with jQuery 3.0. In any case, for a long time, it was nothing more than a wrapper around JSON.parse().
Example
const json = '{ "city": "Boston", "population": 500000 }';
const object = JSON.parse(json);
console.log(object.city, object.population);
Browser Compatibility
Is JSON.parse supported by all major browsers?
Pretty much, yes (see reference).
Older question, I know, however nobody notice this solution by using new Function(), an anonymous function that returns the data.
Just an example:
var oData = 'test1:"This is my object",test2:"This is my object"';
if( typeof oData !== 'object' )
try {
oData = (new Function('return {'+oData+'};'))();
}
catch(e) { oData=false; }
if( typeof oData !== 'object' )
{ alert( 'Error in code' ); }
else {
alert( oData.test1 );
alert( oData.test2 );
}
This is a little more safe because it executes inside a function and do not compile in your code directly. So if there is a function declaration inside it, it will not be bound to the default window object.
I use this to 'compile' configuration settings of DOM elements (for example the data attribute) simple and fast.
Summary:
Javascript (both browser and NodeJS) have a built in JSON object. On this Object are 2 convenient methods for dealing with JSON. They are the following:
JSON.parse() Takes JSON as argument, returns JS object
JSON.stringify() Takes JS object as argument returns JSON object
Other applications:
Besides for very conveniently dealing with JSON they have can be used for other means. The combination of both JSON methods allows us to make very easy make deep clones of arrays or objects. For example:
let arr1 = [1, 2, [3 ,4]];
let newArr = arr1.slice();
arr1[2][0] = 'changed';
console.log(newArr); // not a deep clone
let arr2 = [1, 2, [3 ,4]];
let newArrDeepclone = JSON.parse(JSON.stringify(arr2));
arr2[2][0] = 'changed';
console.log(newArrDeepclone); // A deep clone, values unchanged
You also can use reviver function to filter.
var data = JSON.parse(jsonString, function reviver(key, value) {
//your code here to filter
});
For more information read JSON.parse.
Just to the cover parse for different input types
Parse the data with JSON.parse(), and the data becomes a JavaScript object.
var obj = JSON.parse('{ "name":"John", "age":30, "city":"New York"}');
When using the JSON.parse() on a JSON derived from an array, the method will return a JavaScript array, instead of a JavaScript object.
var myArr = JSON.parse(this.responseText);
console.log(myArr[0]);
Date objects are not allowed in JSON.
For Dates do somthing like this
var text = '{ "name":"John", "birth":"1986-12-14", "city":"New York"}';
var obj = JSON.parse(text);
obj.birth = new Date(obj.birth);
Functions are not allowed in JSON.
If you need to include a function, write it as a string.
var text = '{ "name":"John", "age":"function () {return 30;}", "city":"New York"}';
var obj = JSON.parse(text);
obj.age = eval("(" + obj.age + ")");
Another option
const json = '{ "fruit": "pineapple", "fingers": 10 }'
let j0s,j1s,j2s,j3s
console.log(`{ "${j0s="fruit"}": "${j1s="pineapple"}", "${j2s="fingers"}": ${j3s="10"} }`)
Try this. This one is written in typescript.
export function safeJsonParse(str: string) {
try {
return JSON.parse(str);
} catch (e) {
return str;
}
}