I have an api getData method which returns json data every minute in angularjs.
function($scope, $http,$timeout, confirm) {
(function tick() {
$http.get('myapi.json').success(function(data) {
$scope.operation = data ;
$timeout(tick, 60000);
})
})();
JSON DATA looks like this.
[{ "requests" :"200"} ....]
After every minute the "requests" value changes. I want to find the difference between the previous request value and current request value. I tried $scope.$watch but doesn't give the object value change. Please let me know how to solve this?
Related
i am newbie en react technologie.
how can i get the json data from http request ?
as you can see on
i can get the value of console.log(dataExt); from inside this function,
but i can not get the value of console.log(dataExt); from outside this function.
i miss something ?
i did use return dataExt; why i get nothing ?
i have modified my function:
async function getDataExt()
{
try {
let response = await fetch('https://xxxx');
let dataExt = await response.json();
console.log(dataExt);
return dataExt;
} catch(error) {
console.error(error);
}
}
but still i can not get the value
The fetch call is asynchronous and returns a Promise, that's why you need to call then to get the result. As it stands, line 62 will not wait for the fetch in getDataExt() to complete before running the console.log. You need to treat getDataExt as an async function and either do async/await or .then().
It is because of the asynchrony, that is, the "return" is executed when it obtains the value in the request it makes, and that takes time. Let's say it takes 1 second for the data to return, but 0.1 for the variable to print, that means it prints first and then assigns the value. Now, a possible solution would be to create a "state" to save that data or how the partner said, create the function getDataExt as an asynchronous function.
This is a slightly messy questions. Although it appears I'm asking question about amCharts, I really just trying to figure how to extract an array from HTTP request and then turn it into a variable and place it in to 3-party javacript.
It all starts here, with this question, which was kindly answered by AmCharts support.
As one can see from the plnker. The chart is working. Data for the chart is hard coded:
`var chartData = [{date: new Date(2015,2,31,0,0,0, 0),value:372.10,volume:2506100},{date: new Date(2015,3,1,0, 0, 0, 0),value:370.26,volume:2458100},{date: new Date(2015,3,2,0, 0, 0, 0),value:372.25,volume:1875300},{date: new Date(2015,3,6,0, 0, 0, 0),value:377.04,volume:3050700}];`
So we know the amCharts part works. Know where the problem is changing hard coded data to a json request so it can be dynamic. I don't think this should be tremendously difficult, but for the life of me I can't seem figure it out.
The first issue is I can't find any documentation on .map, .subscribe, or .observable.
So here is a plunker that looks very similar to the first one, however it has an http providers and injectable. It's broken, because I can't figure out how to pull the data from the service an place it into the AmCharts function. I know how pull data from a http provider and display it in template using NgFor, but I don't need it in the template (view). As you can see, I'm successful in transferring the data from the service, with the getTitle() function.
this.chart_data =_dataService.getEntries();
console.log('Does this work? '+this.chart_data);
this.title = _dataService.getTitle();
console.log('This works '+this.title);
// Transfer the http request to chartData to it can go into Amcharts
// I think this should be string?
var chartData = this.chart_data;
So the ultimate question is why can't I use a service to get data, turn that data into a variable and place it into a chart. I suspect a few clues might be in options.json as the json might not be formatted correctly? Am I declaring the correct variables? Finally, it might have something to do with observable / map?
You have a few things here. First this is a class, keep it that way. By that I mean to move the functions you have inside your constructor out of it and make them methods of your class.
Second, you have this piece of code
this.chart_data =_dataService.getEntries().subscribe((data) => {
this.chart_data = data;
});
What happens inside subscribe runs asynchronously therefore this.chart_data won't exist out of it. What you're doing here is assigning the object itself, in this case what subscribe returns, not the http response. So you can simply put your library initialization inside of the subscribe and that'll work.
_dataService.getEntries().subscribe((data) => {
if (AmCharts.isReady) {
this.createStockChart(data);
} else {
AmCharts.ready(() => this.createStockChart(data));
}
});
Now, finally you have an interesting thing. In your JSON you have your date properties contain a string with new Date inside, that's nothing but a string and your library requires (for what I tested) a Date object, so you need to parse it. The problem here is that you can't parse nor stringify by default a Date object. We need to convert that string to a Date object.
Look at this snippet code, I used eval (PLEASE DON'T DO IT YOURSELF, IS JUST FOR SHOWING PURPOSES!)
let chartData = [];
for(let i = 0; i < data[0].chart_data.length; i++) {
chartData.push({
// FOR SHOWING PURPOSES ONLY, DON'T TRY IT AT HOME
// This will parse the string to an actual Date object
date : eval(data[0].chart_data[i].date);
value : data[0].chart_data[i].value;
volume : data[0].chart_data[i].volume;
});
}
Here what I'm doing is reconstructing the array so the values are as required.
For the latter case you'll have to construct your json using (new Date('YOUR DATE')).toJSON() and you can parse it to a Date object using new Date(yourJSON) (referece Date.prototype.toJSON() - MDN). This is something you should resolve in your server side. Assuming you already solved that, your code should look as follows
// The date property in your json file should be stringified using new Date(...).toJSON()
date : new Date(data[0].chart_data[i].date);
Here's a plnkr with the evil eval. Remember, you have to send the date as a JSON from the server to your client and in your client you have to parse it to a Date.
I hope this helps you a little bit.
If the getEntries method of DataService returns an observable, you need to subscribe on it to get data:
_dataService.getEntries().subscribe(
(data) => {
this.chart_data = data;
});
Don't forget that data are received asynchronously from an HTTP call. The http.get method returns an observable (something "similar" to promise) will receive the data in the future. But when the getEntries method returns the data aren't there yet...
The getTitle is a synchronous method so you can call it the way you did.
I'm using node, express, and mongoose.
I have a function that performs a search in a database and sends the response in a JSON format with:
res.jsonp(search_result);
This displays the correctly returned result in the browser as a JSON object. My question is, how do I get that JSON object?
I've tried returning search_result but that gives me null (possibly because asynchronous). I'd also like to not edit the current function (it was written by someone else). I'm calling the function and getting a screen full of JSON, which is what res.jsonp is supposed to do.
Thanks in advance.
Just make a new function that takes this JSON as parameter and place it inside the old one. Example:
// Old function
app.get('/', function(req,res){
// recieve json
json_object = .....
// Get json to your function
processJson(json_object);
// Old function stuff
.
.
.
});
function processJson(json_object) {
// Here you'll have the existing object and can process it
json_object...
}
I am currently having trouble of reloading a json store with new parameters. Here is my store:
newsletters = new Ext.data.JsonStore({
url: '/newsletters/',
root: 'results',
fields: [
'id',
'body'
'recipients'
],
baseParams: { command: 'json', to: dateTo, from: dateFrom },
autoLoad: true
});
dateTo and dateFrom are initally empty strings ( '' ) and checking in firebug /newsletters is called with the correct parameters.
Now none of the following techniquest work:
Changing the values of dateTo and dateFrom then calling newsletters.reload() still calls the page with the parameters to and from being empty strings.
Calling newsletters.reload( { to: 'test1', from: 'test2' } ); still sees the parameters as empty strings.
Finally as from the manual I have tried:
lastOptions = newsletters.lastOptions;
Ext.apply(lastOptions.params, {
to: 'test1',
from: 'test2'
});
newsletters.reload(lastOptions);
This again does not request /newsletters with the updated parameters.
Any advice appreciated!
You can actually pass params object to the load() method
newsletters.load({
params: {to: 'test1', from: 'test2'}
})
From the docs, you can probably do :
store.setBaseParam('to', dateTo);
Now, if I understand correctly, you want your baseParams to be changed whenever dateTo and dateFrom are changed.
You could try :
var dateTo = '', dateFrom = '';
store.on('beforeload', function(s) {
s.setBaseParam('to', dateTo);
s.setBaseParam('from', dateFrom);
});
// This should work :
dateTo = 1;
dateFrom = 2;
store.load();
My problem was: I have a store that shall request data over a proxy to back-end. This request shall hold a parameter named filter, which will just help back-end to decide which is the set of result the client is interested in. This parameter is loaded from a Combobox or some other component which the user can use to express which filter shall be used.
From my point of view the parameters shouldn't be set to the Store and neither using the load parameter. I will explain why:
Configuring parameters to the store would imply that every other component using the same store will have this parameters configured, meaning you can have concurrence problems.
And on the second case, it is not interesting to have it configurable over load method, because you don't wanna every single time explicit make use of the load method by your self, remember that there are already some components like paging and custom components that triggers this method.
What would be the right way from my point of view:
Every time that a load is triggered, we just attach the additional parameter in a non-intrusive way. Meaning that the trigger will not need to have any change (remember here trigger could be any component that executes store.load()) and the store shall be not aware about this new parameter.
You can see here clearly that this shall be an operation done before request data to proxy, and in my case I implemented as a listener for the beforeload event. When beforeload is executed, I just aggregate the new parameters to the operation parameter of the listener that according documentation is: beforeload( store, operation, eOpts ). The final implementation is something like:
store.on({
beforeload: function (store, operation, opts) {
Ext.apply(operation, {
params: {
filterName: Ext.getCmp('filterCombo').getValue()
}
});
}
});
Ive been stuck with this issue for some time
My JSon store fields need to retrieve some more info:
{ name: "ExpirationDate", convert: convertDate },
{ name: "AffectedObject", convert: GetValue },
The date method is working fine but the result from GetValue is not being rendered on the grid even though the code is working and returning the correct value (either with or without JSON):
function GetValue(v) {
var conn = new Ext.data.Connection();
conn.request({
url: 'test/GetObjectByID',
method: 'POST',
params: { id: v },
scriptTag: true,
success: function (response) {
console.log(response.responseText);
ReturnResult(response.responseText);
},
failure: function () {
Ext.Msg.alert('Status', 'Something went wrong');
}
});
function ReturnResult(str) {
return Ext.util.JSON.decode(str.toString());
}
Any idea why the result is not not showing?
The 'convert' property is expecting an immediate return value. Your GetValue function is issuing an asynchronous request and then immediately returning nothing. At some arbitrary point in the future after the request completes the 'success' function is called, but it is no longer connected to the original call so any value it may return is meaningless.
Though you could make it work by replacing the use of Ext.data.Connection with manually constructed synchronous requests, I recommend reconsidering the mechanism by which you are getting this data. Issuing a separate request for every record in your data store is less than optimal.
The best solution is to bring that additional data in on the server side and include it in the response to the store proxy's initial request. If that cannot be done then you can try listening to the store's 'load' event and performing conversion for all loaded records with a single request. Any grids or other views you have reading from the store may have to be configured to display dummy text in place of the missing data until the conversion request completes.