Preparing specific JSON structure with array

Question

I'm trying to prepare a JSON with a certain structure to send over REST. Every 250 events, I want to send a JSON payload with those events. I'm trying to emulate this using the code below, but it is not returning anything.

var eventQueue = new Array();
for (j = 0; j < 251; j++) {
 var curr_timestamp = new Date().getTime();
 eventQueue.push({
 "client_ip" : "127.0.0.1",
 "timestamp" : curr_timestamp,
 "user_name" : "Robert"
 });
 if(j = 250) {
 var jString = JSON.stringify(eventQueue);
 var payload = '{"root":{"user_data":[' + jString + ']}}';
 }
}

The JSON payload structure I need to create looks like:

{ 
 "root":{ 
 "user_data":[ 
 { 
 "client_ip":"127.0.0.1",
 "timestamp":"1723452955",
 "user_name":"Robert"
 },
 { 
 "client_ip":"127.0.0.1",
 "timestamp":"1723452956",
 "user_name":"Robert"
 },
 { 
 "client_ip":"127.0.0.1",
 "timestamp":"1723452957",
 "user_name":"Robert"
 },
 ...
 ]
 }
}

Should I be using join instead to prepare the structure or is there a better approach?

• StackSlave: j = 250 is assignment.

Answer 1

You are using j = 0 incorrectly. At the very least it should be j==0. But if you want this to happen every 250 events then you can use mod (%)

var eventQueue = new Array();
for (j = 0; j < 251; j++) {
 var curr_timestamp = new Date().getTime();
 eventQueue.push({
 "client_ip" : "127.0.0.1",
 "timestamp" : curr_timestamp,
 "user_name" : "Robert"
 });
 if(j % 250 == 0) {
 var jString = JSON.stringify(eventQueue);
 var payload = '{"root":{"user_data":[' + jString + ']}}';
 }}

Answer 2

Your code should look like this:

var resObj = {root:{user_data:[]}};
for(var i=0; i<251; i++){;
 resObj.root.user_data.push({
 client_ip: '127.0.0.1',
 timestamp: new Date().getTime(),
 user_name: 'Robert'
 });
}
console.log(resObj);

Answer 3

PHPglue is right. and eventQueue is an array, so JSON.stringify() will return string with spare brackets around it. you dont need to add additional []. otherwise it would be user_data: [[...]]

Answer 4

var eventQueue = [];
for (var j = 0; j < 250; j++) {
 eventQueue.push({
 client_ip: "127.0.0.1",
 timestamp: new Date().getTime(),
 user_name: "Robert"
 });
}
var payload = JSON.stringify({
 root: {
 user_data: eventQueue
 }
});