I did not want to use layers url in arcgis. Instead I want to use json data in arcgis can we do that?
var tileLayer = new ArcGISTiledMapServiceLayer("http://tiles.arcgis.com/tiles/nzS0F0zdNLvs7nc8/arcgis/rest/services/US_Counties_basemap/MapServer ");
map.addLayer(tileLayer);
var layerUrl = "http://services.arcgis.com/P3ePLMYs2RVChkJx/arcgis/rest/services/USA_Counties_Generalized/FeatureServer/0";
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I'm making mobile app with React-Native and i wanna get data from my API.But my API's datas , databases has html tags (you can see them in images which i shared) and some character codes because there are also Turkish characters.I already was using this API from my web site and there was no problem but when i try to get data to my react native app , it is getting data as a plain text as you see in my images.How can i get this datas without problem
It's called HTML entity. This is the code that works on browser (not on your case)
var decodeEntities = (function() {
// this prevents any overhead from creating the object each time
var element = document.createElement('div');
function decodeHTMLEntities (str) {
if(str && typeof str === 'string') {
// strip script/html tags
str = str.replace(/<script[^>]*>([\S\s]*?)<\/script>/gmi, '');
str = str.replace(/<\/?\w(?:[^"'>]|"[^"]*"|'[^']*')*>/gmi, '');
element.innerHTML = str;
str = element.textContent;
element.textContent = '';
}
return str;
}
return decodeHTMLEntities;
})();
The code are copied from here HTML Entity Decode
But it only works on the browser because the browser are automatically translate the characters for you.
I don't think passing around unserialized data like this is a good idea. You might want to encode data in server side using url encode or something then decode it in the react-native side
Reference
https://www.w3schools.com/charsets/ref_utf_punctuation.asp
Actually i solved it with this : https://github.com/archriss/react-native-render-html
Thanks
Is it possible to read ArcGIS CSVLayer Source from an object rather than a file like .csv or .geojson?
I have data in my database about an object including Latitude, Longitude and Altitude. When I want to display these objects onto the map, now I should be creating a CSV file or a GeoJson file.
Is there any way that I could provide these data to the CSVLayer without creating these files but reading directly from an Object(JavaScript Array or Object)
The simplest way to do this is serialize your JavaScript Array into a Blob object and pass it's URL to CSVLayer.url.
var csvContent = [
"time,latitude,longitude,depth,mag",
"2019-06-28T11:17:31.734Z,8.4069,-82.8409,22.89,4.4",
"2019-06-28T09:24:08.880Z,37.5128326,-118.7975006,6.01,2.8",
"2019-06-28T08:30:42.866Z,-29.3884,-70.916,81.42,5"
].join("\n");
const blob = new Blob([csvContent], {type: "text/csv"});
const url = URL.createObjectURL(blob);
var csvLayer = new CSVLayer({ url });
See the following CodePen that uses above technique to show USGS earthquake data: https://codepen.io/arnofiva/pen/0ebf1e5fd85f36c09b6d87e15b7956b1
Pretty straight forward: I am simply trying to get a feature layer
var floodLayer = new FeatureLayer("URL");
and convert it to a polygon array similar to:
var polygons = [];
for (var i = 0; i < floodLayer.graphics.length; i++) {
var polygons[i] = new Polygon({ "rings": floodLayer.graphics[i].rings, "spatialReference": floodLayer.graphics[i].spatialReference });
}
However, feature layers don't appear to have the appropriate properties to create polygons. Unless I am missing something?
rings and spatialReference are properties of geometry which is a property of your graphics. So you need to use floodLayer.graphics[i].geometry.rings instead of floodLayer.graphics[i].rings, for example.
I am having trouble with blob URLs.
I was searching for src of a video tag on YouTube and I found that the video src was like:
src="blob:https://video_url"
I opened the blob URL that was in src of the video, but it gave an error. I can't open the link, but it was working with the src tag. How is this possible?
I have a few questions:
What is a blob URL?
Why it is used?
Can I make my own blob URL on a server?
Any additional details about blob URLs would be helpful as well.
Blob URLs (ref W3C, official name) or Object-URLs (ref. MDN and method name) are used with a Blob or a File object.
src="blob:https://crap.crap" I opened the blob url that was in src of
video it gave a error and i can't open but was working with the src
tag how it is possible?
Blob URLs can only be generated internally by the browser. URL.createObjectURL() will create a special reference to the Blob or File object which later can be released using URL.revokeObjectURL(). These URLs can only be used locally in the single instance of the browser and in the same session (ie. the life of the page/document).
What is blob url?
Why it is used?
Blob URL/Object URL is a pseudo protocol to allow Blob and File objects to be used as URL source for things like images, download links for binary data and so forth.
For example, you can not hand an Image object raw byte-data as it would not know what to do with it. It requires for example images (which are binary data) to be loaded via URLs. This applies to anything that require an URL as source. Instead of uploading the binary data, then serve it back via an URL it is better to use an extra local step to be able to access the data directly without going via a server.
It is also a better alternative to Data-URI which are strings encoded as Base-64. The problem with Data-URI is that each char takes two bytes in JavaScript. On top of that a 33% is added due to the Base-64 encoding. Blobs are pure binary byte-arrays which does not have any significant overhead as Data-URI does, which makes them faster and smaller to handle.
Can i make my own blob url on a server?
No, Blob URLs/Object URLs can only be made internally in the browser. You can make Blobs and get File object via the File Reader API, although BLOB just means Binary Large OBject and is stored as byte-arrays. A client can request the data to be sent as either ArrayBuffer or as a Blob. The server should send the data as pure binary data. Databases often uses Blob to describe binary objects as well, and in essence we are talking basically about byte-arrays.
if you have then Additional detail
You need to encapsulate the binary data as a BLOB object, then use URL.createObjectURL() to generate a local URL for it:
var blob = new Blob([arrayBufferWithPNG], {type: "image/png"}),
url = URL.createObjectURL(blob),
img = new Image();
img.onload = function() {
URL.revokeObjectURL(this.src); // clean-up memory
document.body.appendChild(this); // add image to DOM
}
img.src = url; // can now "stream" the bytes
This Javascript function supports to show the difference between the Blob File API and the Data API to download a JSON file in the client browser:
/**
* Save a text as file using HTML <a> temporary element and Blob
* #author Loreto Parisi
*/
var saveAsFile = function(fileName, fileContents) {
if (typeof(Blob) != 'undefined') { // Alternative 1: using Blob
var textFileAsBlob = new Blob([fileContents], {type: 'text/plain'});
var downloadLink = document.createElement("a");
downloadLink.download = fileName;
if (window.webkitURL != null) {
downloadLink.href = window.webkitURL.createObjectURL(textFileAsBlob);
} else {
downloadLink.href = window.URL.createObjectURL(textFileAsBlob);
downloadLink.onclick = document.body.removeChild(event.target);
downloadLink.style.display = "none";
document.body.appendChild(downloadLink);
}
downloadLink.click();
} else { // Alternative 2: using Data
var pp = document.createElement('a');
pp.setAttribute('href', 'data:text/plain;charset=utf-8,' +
encodeURIComponent(fileContents));
pp.setAttribute('download', fileName);
pp.onclick = document.body.removeChild(event.target);
pp.click();
}
} // saveAsFile
/* Example */
var jsonObject = {"name": "John", "age": 30, "car": null};
saveAsFile('out.json', JSON.stringify(jsonObject, null, 2));
The function is called like saveAsFile('out.json', jsonString);. It will create a ByteStream immediately recognized by the browser that will download the generated file directly using the File API URL.createObjectURL.
In the else, it is possible to see the same result obtained via the href element plus the Data API, but this has several limitations that the Blob API has not.
I have modified working solution to handle both the case.. when video is uploaded and when image is uploaded .. hope it will help some.
HTML
<input type="file" id="fileInput">
<div> duration: <span id='sp'></span><div>
Javascript
var fileEl = document.querySelector("input");
fileEl.onchange = function(e) {
var file = e.target.files[0]; // selected file
if (!file) {
console.log("nothing here");
return;
}
console.log(file);
console.log('file.size-' + file.size);
console.log('file.type-' + file.type);
console.log('file.acutalName-' + file.name);
let start = performance.now();
var mime = file.type, // store mime for later
rd = new FileReader(); // create a FileReader
if (/video/.test(mime)) {
rd.onload = function(e) { // when file has read:
var blob = new Blob([e.target.result], {
type: mime
}), // create a blob of buffer
url = (URL || webkitURL).createObjectURL(blob), // create o-URL of blob
video = document.createElement("video"); // create video element
//console.log(blob);
video.preload = "metadata"; // preload setting
video.addEventListener("loadedmetadata", function() { // when enough data loads
console.log('video.duration-' + video.duration);
console.log('video.videoHeight-' + video.videoHeight);
console.log('video.videoWidth-' + video.videoWidth);
//document.querySelector("div")
// .innerHTML = "Duration: " + video.duration + "s" + " <br>Height: " + video.videoHeight; // show duration
(URL || webkitURL).revokeObjectURL(url); // clean up
console.log(start - performance.now());
// ... continue from here ...
});
video.src = url; // start video load
};
} else if (/image/.test(mime)) {
rd.onload = function(e) {
var blob = new Blob([e.target.result], {
type: mime
}),
url = URL.createObjectURL(blob),
img = new Image();
img.onload = function() {
console.log('iamge');
console.dir('this.height-' + this.height);
console.dir('this.width-' + this.width);
URL.revokeObjectURL(this.src); // clean-up memory
console.log(start - performance.now()); // add image to DOM
}
img.src = url;
};
}
var chunk = file.slice(0, 1024 * 1024 * 10); // .5MB
rd.readAsArrayBuffer(chunk); // read file object
};
jsFiddle Url
https://jsfiddle.net/PratapDessai/0sp3b159/
The OP asks:
What is blob URL? Why is it used?
Blob is just byte sequence. Browsers recognize Blobs as byte streams. It is used to get byte stream from source.
According to Mozilla's documentation
A Blob object represents a file-like object of immutable, raw data. Blobs represent data that isn't necessarily in a JavaScript-native format. The File interface is based on Blob, inheriting blob functionality and expanding it to support files on the user's system.
The OP asks:
Can i make my own blob url on a server?
Yes you can there are several ways to do so for example try http://php.net/manual/en/function.ibase-blob-echo.php
Read more here:
https://developer.mozilla.org/en-US/docs/Web/API/Blob
http://www.w3.org/TR/FileAPI/#dfn-Blob
https://url.spec.whatwg.org/#urls
blob urls are used for showing files that the user uploaded, but they are many other purposes, like that it could be used for secure file showing, like how it is a little difficult to get a YouTube video as a video file without downloading an extension. But, they are probably more answers. My research is mostly just me using Inspect to try to get a YouTube video and an online article.
Another use case of blob urls is to load resources from the server, apply hacks and then tell the browser to interpret them.
One such example would be to load template files or even scss files.
Here is the scss example:
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.11.1/sass.sync.min.js"></script>
function loadCSS(text) {
const head = document.getElementsByTagName('head')[0]
const style = document.createElement('link')
const css = new Blob([text], {type: 'text/css'})
style.href = window.URL.createObjectURL(css)
style.type = 'text/css'
style.rel = 'stylesheet'
head.append(style)
}
fetch('/style.scss').then(res => res.text()).then(sass => {
Sass.compile(sass, ({text}) => loadCSS(text))
})
Now you could swap out Sass.compile for any kind of transformation function you like.
Blob urls keeps your DOM structure clean this way.
I'm sure by now you have your answers, so this is just one more thing you can do with it.
I have some problem on this. Can I get public tagged photo from Instagram api without getting any code or access token?
Please share any link for reading because I cannot found any. I feel it is less knowledge about Instagram api on web.
Thanks!
You can pull public media by tag without authentication.
Take a look at the API documentation for the get /tags/tag-name/media/recent endpoint. Here's the URL: http://instagram.com/developer/endpoints/tags/#get_tags_media_recent
The documentation can be confusing, it shows using an access_token for this endpoint in the example, but it is not required. You will need to register an application and get a client ID.
I use MeteorJS and call a method server side that returns essentially the 'view source' of the instagram page. So if you can run a server side scrape on the tag url you will be able to handle the response with what i have below and it will push all the images into an array.
//server side method
Meteor.methods({
'scrapeInst':function(tag){
return Scrape.url('https://www.instagram.com/explore/tags/'+tag+'/')
}})
//client side logic
Meteor.call('scrapeInst',Session.get('params').tag,function(err,resp){
var theInstResp = resp;
cleanOne = resp.replace(/>|window._sharedData = |;</|;|#47;|<|/g,'').split('script')
var splitter = cleanOne[22].split(',');
var theArr = [];
_.each(splitter,function(e){
var theFinal = {};
var theS = e.split(":");
if(theS[0].replace(/"| |/g,'') === "display_src"){
theFinal[theS[0].replace(/"| |/g,'')] = theS[2].replace(/%22/g,'');
theArr.push(theFinal)
}
});
Session.set('photos',theArr);
setTimeout(function(){
Session.set('loading',false)
},1000)
})