is it possible to bind to a method instead of property in Xamarin Forms, similar to {Binding GetImage()}, I have to download encrypted images those are in encrypted string format from web server and display those images on listview, for that i have to use the async and await operators, but with property, i cannot use those operators.
Related
I was building a demo application for a store (not a specific one) and I got the data from an online JSON file through http requests, is it possible to pass the data to another file?
I tried to pass the data using an object from the where I extracted the data and using sharedPreferences too expecting to pass the data to the other screen and display it, but the actual output was nothing.
you can share data from one page to another page using arguments property of push method
Navigator.of(context).pushNamed("routeName",arguments: data);
to extract this data in the second page use this
ModalRoute.of(context)!.settings.arguments;
In my Flutter (Android/iOS) app I am using Firebase Dynamic Links for Patreon.com OAuth2 apis.
My dynamic link is https://myappname.page.link/patreon
The deep link is https://myappname.net/patreon
Patreon is using the https://myappname.page.link/patreon as a redirect_url , and is supposed to append some parameters to it, so it looks like
https://myappname.net/patreon?code=xxx
However, all I receive inside my app is the naked url https://myappname.net/patreon
There are no parameters attached to it.
So how can I tell Firebase to preserve the query parameters Patreon is attaching to the redirect_url?
As an alternate question, is there a better way to listen for incoming response inside of a Flutter app, without the use of Dynamic Links?
You loose all parameters by using that.
If you're relying on Patreon to send back that parameter I'd suggest to generate a small proxy where you can redirect your calls to the dynamic link by generating it on the fly.
So:
Patreon shares www.myhost.com/supah-link?p1=aaa&p2=bbb
Your micro-service which runs on www.myhost.com/supah-link receives the call
You generate a dynamic link like the following:
https://example.page.link/?link=https://www.example.com/someresource&apn=com.example.android&amv=3&ibi=com.example.ios&isi=1234567&ius=exampleapp&p1=aaa&p2=bbb
NOTE: Pay attention to the &p1=aaa&p2=bbb parameters added
Return a 302 and redirect to your newly generated link
Based on how you configure it from the console this link can redirect to the store or your app, in your app you can listen for the link as follows:
FirebaseDynamicLinks.instance.onLink(
onSuccess: (dynamicLink) async => handleDeepLink(dynamicLink?.link),
);
In handleDeepLink you can parse your custom query parameters.
NOTE: The URL parameter you pass via the dynamic link HAS TO BE ENCODED! Which means your link will look more like this:
https://example.page.link/?link=https%3A%2F%2Fwww.example.com%2Fsomeresource%26apn%3Dcom.example.android%26amv%3D3%26ibi%3Dcom.example.ios%26isi%3D1234567%26ius%3Dexampleapp%26p1%3Daaa%26p2%3Dbbb
I am coding an web app that allows the user to create a type of electronic document using widgets (that I then store in a list view). Is it possible to add this list view to my web app in run time so other users on other devices can access the electronic form?
The only way to do this would be to use some sort of database to hold the resulting "document". You could use Firebase Firestore, the server's file system, or anything else you can connect to. There is no way to easily modify the underlying code, as it is no longer Dart code; it gets transpiled to JavaScript.
Assuming you go with Firestore, you could have something like this:
CollectionReference documentRef = Firestore.instance
.collection('forms')
.document(formId);
documentRef.snapshots().listen((DocumentSnapshot documentSnapshot) {
// Do something with `documentSnapshot`.
// setState(() => _updateForm(documentSnapshot.data.data()));
});
Problem:
I need to be able to remove all link decoration from the download URL that is generated for images in Firebase Storage.
However, when all link decoration is stripped away, the resulting link currently would return a JSON document of the image's metadata.
Context:
The flow goes as follows:
An image is uploaded to Firebase from an iOS app. Once that is done the download URL is then sent in a POST request to an external server.
The server that the URL is being sent to doesn't accept link decoration when submitting image URLs.
Goal:
Alter the Firebase Storage download URL such as it is stripped of all link decoration like so:
https://firebasestorage.googleapis.com/v0/b/example.appspot.com/o/[FOLDER_NAME]%[IMAGE_NAME].jpg
Notes:
The problem is twofold really, first the link needs to be manipulated to remove all the link decoration. Then the behavior of the link needs to changed, since in order to return an image, you need ?alt=media following the file extension, in this case .jpg. Currently, without link decoration, using the link with my desired structure would return a JSON document of the metadata.
The current link structure is as follows:
https://firebasestorage.googleapis.com/v0/b/example.appspot.com/o/[FOLDER_NAME]%[IMAGE_NAME].jpg?alt=media&token=[TOKEN]
Desired link structure:
https://firebasestorage.googleapis.com/v0/b/example.appspot.com/o/[FOLDER_NAME]%[IMAGE_NAME].jpg
The token is necessary for accessing the image depending security rules in place, but can be ignored with the proper read permissions. I can adjust the rules as needed, but I still need to be able to remove the ?alt=media and still return an image.
Building up on Frank's answer, if you access to your associated Google Cloud Platform project, find the bucket in the Storage tab and make this bucket public, you will be able to get the image from here with the format you wish. That is, you will not be accessing through Firebase
https://firebasestorage.googleapis.com/v0/b/example.appspot.com/o/[FOLDER_NAME]%[IMAGE_NAME].jpg
but through Google Cloud Storage, with a link like
https://storage.googleapis.com/[bucket_name]/[path_to_image]
Once in your GCP project Console, access the Storage bucket with the same name as the one you have in your Firebase project. They are the same bucket. Then make the bucket public by following these steps. After that, you will be able to construct your links as mentioned above and they will be accessible with no token and no alt=media param. If you do not want to make the public to everyone, you will be able to play around with the permissions there as you wish.
You could split the url string into two halves by using String.componentsSeparatedByString(_ separator:)
Storage.storage().reference().child(filePath).downloadURL(completion: { (url, error) in
let urlString = url.absoluteString
let urlStringWithoutQueryString = urlString.componentsSeparatedByString("?").first!
})
Calling .downloadURL on a StorageReference will return you that URL, but this method can be used to remove the query string from any URL. String.componentsSeparatedByString(_ separator:) breaks a String into an array of Strings, splitting the string by any occurrence of a given separator, in this case ?.
NOTE this method assumes that ? occurs only once within the url string, which I believe is the case for all Firebase Storage urls.
You should treat the download URL that you get back from Firebase as an opaque string. There's no way to strip the parameters from a download URL without breaking that download URL.
If you want to allow public access to the files in your bucket with simpler URLs, consider making the object in your (or even your entire) bucket public.
I i'm wondering if it is possible to call a javascript function from my application. The js function is on the server. Let's say i have a some inputs in the app. Then i have this submit button which calls the IBAction, from the IBAction i want to call:
function mySubmit(){
document.getElementById("myForm").submit();
}
and pass it the data the user entered and then get back a response (in my app) not in the server
Is this possible to do? if so, can you provide some useful links?
Thanks in advance and have a nice saturday ;)
The js function is on the server
Are you sure this is your case? Don't you mean that your js submits a form that is itself treated on the server side?
Javascript is normally a client-side scripting language, which is executed on client-side, contrary to e.g. PHP which is only executed server-side.
[EDIT] (As stated by #Dr.Dredel in the comments, as there exists server-side javascript, but these usages are not yet very common and I don't think it corresponds to your context)
If you need to call a javascript function from an already loaded HTML page in a WebView, you can simply use the UIWebView's stringByEvaluatingJavascriptFromString:. You can pass a string representing javascript code to this function, so you can build a string that represent a function call with string or int arguments for example without any problem.
But if you intend to load your HTML page just to call a javascript fonction which in turn submit a form that sends the form's data to your server… This is clearly the wrong way!
You should instead considering performing the NSURLRequest to your server directly in Objective-C (maybe using ASIHTTPRequest to perform a POST request and easily set the values for each keys of the form you intend to send). In addition, doing this directly in ObjC will avoid loading the HTML page for nothing and rely on the js script, and will allow you to directly get the response in the delegate method.