I have the following code which retrieves values from a simple 3 input form:
//retrieves data from a form
var $form = $( this ),
prgname= $form.find('input[name="prg"]').val(),
startDate = $("#startdate").datepicker({ dateFormat: 'yy-mm-dd' }).val(),
endDate = $("#enddate").datepicker({ dateFormat: 'yy-mm-dd' }).val();
The following code sends the request to the server:
var request = $.ajax({
url: "/prg/",
type: "post",
data: JSON.stringify({prg: prgname, start:startDate, end:endDate}),
contentType: 'application/json',
dataType: 'json',
success: function() {},
error: function (jqXHR, textStatus, errorThrown){};
on the server end using python and webapp2 Im doing the following, (here is where I am unsure of things)
import json
class PrgHandler(webapp2.RequestHandler):
def post(self):
prg= cgi.escape(self.request.POST['prg'])
start_date = cgi.escape(self.request.POST['start'])
end_date = cgi.escape(self.request.POST['end'])
#some code to write to db here
....
#if successful return a success message
if success:
success_msg = [{'class': 'success', 'msg': 'Successfully saved to the database'}]
else:
success_msg = [{'class': 'error', 'msg': 'Could not saved to the database'}]
data_string = json.dumps(success_msg)
self.response.headers.add_header('content-type', 'application/json', charset='utf-8')
self.response.write(data_string)
When I get the response it is skipping the success function and going directly to the error.
Logging the error values im not getting any thing meaningful:
the error is:
The text status is:error
The jqXHR is:[object Object]
Chrome's console is giving me the error:
Resource interpreted as Document but transferred with MIME type application/json:
I looked that up and the solutions on SO did not work, I think this is an error with the server side code:
self.response.headers.add_header('content-type', 'application/json', charset='utf-8')
If I comment out the above line I get no error in chrome and I just get back the response on a blank page with the correct values in the following format:
[{"msg": "Successfully saved to the database", "class": "success"}]
In the above case it does save to the database so I cannot seem to find anything wrong except for the header and simply don't know how to proceed!
EDIT
The error it seems is from the server side I had removed the following line:
event.preventDefault();
from my script and it caused all the problems now at least Im getting a clear indication of where the problem is. It's from incorrectly getting the posted data, how would I do it the correct way? I tried the following:
json_data = self.request.GET.items()
decoded = json.loads(json_data)
but Im getting a TypeError: expected string or buffer on the following line:
json_data = self.request.GET.items()
Have a look in your debugger. You receive a JSON string in your post (webapp2 multidict). You have to decode this string using json.loads, resulting in a python object.
Here is my jquery code to send and receive json :
function gaeQuery(request) {
var url = "/query";
var payload = {'jsondata' : JSON.stringify(request)};
$.post(
url,
payload,
function(response) {
procesResponse(response);
}, // succes response callback
'json', // response contains JSON content, and will be decoded in a js object
{
contentType: "application/json;charset=utf-8", // send JSON content
timeout: 20000,
tryCount: 0,
retryLimit: 3, // max 3 retries
error: function(xhr, textStatus, errorThrown) { // error handling callback
if (textStatus === 'timeout') {
this.tryCount++;
if (this.tryCount <= this.retryLimit) { //try again until retryLimit
$.ajax(this);
return;
}
alert('We have tried ' + this.retryLimit + ' times and it is still not working. We give in. Sorry.');
return;
}
if (xhr.status === 500) { // internal server error
alert('Oops! There seems to be a server problem, please try again later.');
}
else {
alert('Oops! There was a problem, sorry.'); // something went wrong
}
}
}
);
}
OK so I managed to figure this out and thought I will post the answer that worked for me to help anyone looking for this information because the webapp2 docs are not that helpful when it comes to 'getting' posted json data.
on the client side I did the following:
var request = $.ajax({
url: "/some/url/",
type: "POST",
data: JSON.stringify([{someval: val1, someval2:val2, someval3:val3}]),
contentType: "application/json",
dataType: 'json',
beforeSend: function() {
$('#loading-div').show();
},
complete: function(){
$('#loading-div').hide();
},
success: function(response, textStatus, jqXHR){}
});
The reason I couldnt figure out the problem straight away was because of the following line which I deleted along with some commented out line which prevented the page from redirecting after posting. This was the source of all the weird, unrelated and unhelpful error messages:
event.preventDefault();
on the server side to get the json data being posted to appengine do the following:
jdata = json.loads(cgi.escape(self.request.body))
for vals in jdata:
val1 = vals['someval']
val2 = vals['someval2']
val3 = vals['someval3']
The above was the root of the problem I wasn't doing it right and without the previous line on the client side there was no way to figure it out.
Anyways once you have the data do whatever processing you need to do with it and once you are done and need to send back a json response add the following lines:
//the data would look something like this
data = {'return_value': val1, 'return_value2': val2,
'return_value3': val3, 'return_value4': val4}
return_data = json.dumps(data)
self.response.headers.add_header('content-type', 'application/json', charset='utf-8')
self.response.write(return_data)
Almost forgot on the client side again to access the variables sent back from the server with jquery its very straight forward...do something like:
success: function(response, textStatus, jqXHR){
console.log(response.return_value);
console.log(response.return_value2);
console.log(response.return_value3);
}
Hope this will help someone seeking this information.
Related
Hi i got a python fast api backend server.
#app.get("/getName")
async def getName() -> JSONResponse:
data_sniffer = DataSniffer()
data = json.dumps(data_sniffer.get_data())
print(data)
return JSONResponse(content=data,headers={'content-type':'application/json'})
this is the console output of data :{"first_name": "test"}
My Frontend Code looks like this
useEffect(() => {
async function query() {
const options = {
method: 'GET',
mode: 'no-cors',
headers: {
'Access-Control-Allow-Origin': '*',
'Content-Type': 'application-json',
},
};
const res = await fetch('http://127.0.0.1:3000/getName', options);
console.log(res);
const data = await res.json();
console.log(data);
}
query();
});
but i get following error message SyntaxError: JSON.parse: unexpected end of data at line 1 column 1 of the JSON data
my network response looks like this:
"{"first_name": "test"}"
Has anyone a clue why fetch cant parse the json?
For anyone who has the same issue what worked for me is I moved my Backend folder to the root directory of my Frontend and removed the mode no-cors of the fetch request. I installed the no cors app and now it works. I think the mode no-cors broke my request.
I'm working on a flask web application in which the client posts data to the server in the form of:
{
"sess_id" : 1 ,
"annotations" :
[ {"tag_start" : "TIME","tag_end" : "TIME","tag" : "YOUR_TAG"}, {"tag_start" : "TIME","tag_end" : "TIME","tag" : "YOUR_TAG"}, {"tag_start" : "TIME","tag_end" : "TIME","tag" : "YOUR_TAG"}]
}
Here is the full Ajax post...
$.ajax({
url: 'http://127.0.0.1:5000/api/saveannotation',
type: 'POST',
headers: {'Content-Type' : 'application/json'},
data: {'sess_id' : $('#sessionid_area').val(),
'annotations': JSON.parse(annotations)},
success: function(data) { alert(data.status); }
});
so I can even see this on the api side, which is defined as such:
#sessionapis.route('/saveannotation', methods=['GET', 'POST'])
#login_required
def save_annotation():
rData = request.data
if request.method == 'GET':
return jsonify({'status' : 'success GET'})
else:
return jsonify({'status' : 'success'})
The issue is that data is a "byte" type, not a dict. I also can't call request.json or request.get_json(silent=True), it returns "400 bad request".
Here is a sample of what is in request.data:
b'sess_id=1&annotations%5B0%5D%5Btag_start%5D=2...
it appears to be url encoded for some reason. Values is also empty. If I choose to do something wild, like leave out the content-type = json; I can get a dict-like thing, but I have to access it very oddly. I don't get individual objects, but rather just flat access to all properties.
Any thoughts on how to just get the json parsed into a reasonable object?
Thanks for any hints!
Just passing a content-type header of JSON doesn't actually make the data itself into JSON. You either need to do that yourself, or tell jQuery to do so.
$.ajax({
url: 'http://127.0.0.1:5000/api/saveannotation',
type: 'POST',
contentType: 'application/json',
data: JSON.stringify({'sess_id' : $('#sessionid_area').val(),
'annotations': JSON.parse(annotations)}),
success: function(data) { alert(data.status); }
});
Now your data will be in JSON format and you can get it as a Python dict with request.get_json().
I'm new to web2py, trying to alter an existing application.
I have a JSON object in my JS, which I want to send to the server.
My JS is:
post_data = {ios: [{k:"v"},
{k: "v"},
{k: "v"}]};
$.post("/url", post_data, function(data) {}, "json"); // used with 'json' and without, same results
I want to access this data in my controller. so there, I tried to use request.vars.ios and request.post_vars.ios, getting a None ...
What am I doing wrong?
(note: the data is transmitted, and if i try to dump the request.vars, I get something like
<Storage {'ios[1][ranges_colors]': '', 'ios[0] .... etc which contains the data)
Try this, on the client:
$.ajax({
type: 'POST',
url: '/url.json',
contentType: "application/json; charset=utf-8",
data: post_data,
dataType: 'json',
success: function(data) { alert('Data sent'); }
});
Then on the server:
data = gluon.contrib.simplejson.loads(request.body.read())
I am trying to post some data to a Flask server, whose code is the following:
#app.route('/tasks', methods=['POST'])
def create_task():
if not request.json or not 'title' in request.json:
abort(400)
task = {
'title': request.json['title'],
'description': request.json.get('description', ""),
}
return jsonify({'task' : task}), 201
When I run this, it works fine, and I can make POST requests successfully using curl, with the expected behavior on the back end above and the expected return value in command line. I want to make a post to this server using Swift, however, and am having trouble with that. I have followed the tutorial detailing this behavior here. In particular, I put the code in my AppDelegate.swift so it is executed as soon as the app launches. The full code is in the link posted, but for reference I am also posting it below:
func application(application: UIApplication!, didFinishLaunchingWithOptions launchOptions: NSDictionary!) -> Bool {
var request = NSMutableURLRequest(URL: NSURL(string: "http://localhost:4567/login"))
var session = NSURLSession.sharedSession()
request.HTTPMethod = "POST"
var params = ["username":"jameson", "password":"password"] as Dictionary<String, String>
var err: NSError?
request.HTTPBody = NSJSONSerialization.dataWithJSONObject(params, options: nil, error: &err)
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
var task = session.dataTaskWithRequest(request, completionHandler: {data, response, error -> Void in
println("Response: \(response)")
var strData = NSString(data: data, encoding: NSUTF8StringEncoding)
println("Body: \(strData)")
var err: NSError?
var json = NSJSONSerialization.JSONObjectWithData(data, options: .MutableLeaves, error: &err) as? NSDictionary
// Did the JSONObjectWithData constructor return an error? If so, log the error to the console
if(err != nil) {
println(err!.localizedDescription)
let jsonStr = NSString(data: data, encoding: NSUTF8StringEncoding)
println("Error could not parse JSON: '\(jsonStr)'")
}
else {
// The JSONObjectWithData constructor didn't return an error. But, we should still
// check and make sure that json has a value using optional binding.
if let parseJSON = json {
// Okay, the parsedJSON is here, let's get the value for 'success' out of it
var success = parseJSON["success"] as? Int
println("Succes: \(success)")
}
else {
// Woa, okay the json object was nil, something went worng. Maybe the server isn't running?
let jsonStr = NSString(data: data, encoding: NSUTF8StringEncoding)
println("Error could not parse JSON: \(jsonStr)")
}
}
})
task.resume()
return true
}
However, when I launch this app, I have the following logged in my xcode
Response: <NSHTTPURLResponse: 0x7fc4dae218a0> { URL: http://localhost:5000/task } { status code: 404, headers {
"Content-Length" = 26;
"Content-Type" = "application/json";
Date = "Tue, 07 Oct 2014 19:22:57 GMT";
Server = "Werkzeug/0.9.6 Python/2.7.5";
} }
Body: {
"error": "Not found"
}
Succes: nil
I've been working with this and tinkering with the input, it seems that the back end is fine, but I'm wondering what is wrong with this front end, unfortunately Swift documentation is for the moment fairly moot on this point and seems to be the only solution floating around for RESTful API calls at the moment.
Your flask route is '/tasks' and you're trying to post to http://localhost:5000/task. Is that a typo, or are you a victim of failure to pluralize?
I have a data structure like this:
I'm try to send it to server by $.ajax:
$.ajax({
type: 'POST',
data: post_obj, //this is my json data
dataType: 'json',
url: '',
success: function(e){
console.log(e);
}
});
and I want get it in server by flask: title = request.form['title'] working fine!
But how do I get content ?
request.form.getlist('content') doesn't work.
This is the post data in firebug:
Thanks a lot :D
You are sending your data encoded as query string instead of JSON. Flask is capable of processing JSON encoded data, so it makes more sense to send it like that. Here's what you need to do on the client side:
$.ajax({
type: 'POST',
// Provide correct Content-Type, so that Flask will know how to process it.
contentType: 'application/json',
// Encode your data as JSON.
data: JSON.stringify(post_obj),
// This is the type of data you're expecting back from the server.
dataType: 'json',
url: '/some/url',
success: function (e) {
console.log(e);
}
});
On the server side data is accessed via request.json (already decoded):
content = request.json['content']
If you inspect the POST being submitted by jQuery, you will most likely see that content is actually being passed as content[]. To access it from the Flask's request object, you would then need to use request.form.getlist('content[]').
If you would prefer to have it passed through as content, you can add traditional: true to your $.ajax() call.
More details about this can be found in the 'data' and 'traditional' sections of http://api.jquery.com/jQuery.ajax/.