How to parse and then unparse a url query string so that it ends up in the same format/encoding as before?
Ok the key is the urlencode flag quote_via=urllib.parse.quote
. Additionally, parse_qs could be changed to parse_qsl in order to preserve ordering of parameters, and the keep_blank_labels=True to that function maintains even the blank parameters in the dictionary if you want an absolutely true match.
So now this works for me:
>>> from urllib.parse import quote, parse_qsl,urlencode
>>> urlencode(parse_qsl(working_parse.query,keep_blank_values=True),quote_via=quote) == working_parse.query
True
it takes a complicated query (which you could edit the attributes if you want), parses it out and urlencodes it to the original query string.
Best way to parse URL string to get values for keys?
edit (June 2018): this answer is better. Apple added NSURLComponents
in iOS 7.
I would create a dictionary, get an array of the key/value pairs with
NSMutableDictionary *queryStringDictionary = [[NSMutableDictionary alloc] init];
NSArray *urlComponents = [urlString componentsSeparatedByString:@"&"];
Then populate the dictionary :
for (NSString *keyValuePair in urlComponents)
{
NSArray *pairComponents = [keyValuePair componentsSeparatedByString:@"="];
NSString *key = [[pairComponents firstObject] stringByRemovingPercentEncoding];
NSString *value = [[pairComponents lastObject] stringByRemovingPercentEncoding];
[queryStringDictionary setObject:value forKey:key];
}
You can then query with
[queryStringDictionary objectForKey:@"ad_eurl"];
This is untested, and you should probably do some more error tests.
PHP: Best way to parse URL query without variable name?
If you are sure that nothing malicious would be passed (or you are just testing), then you could do something like:
$output = eval('return ' . parse_url($_SERVER['REQUEST_URI'])['query'] . ';');
echo $output;
Obligatory notice:
Caution
The eval() language construct is very dangerous because it allows execution of arbitrary PHP code. Its use thus is discouraged. If you have carefully verified that there is no other option than to use this construct, pay special attention not to pass any user provided data into it without properly validating it beforehand.
However, I would advise you use the following method and parse the expression with parser in the linked question:
$exp = parse_url($_SERVER['REQUEST_URI'])['query']; // 1+1
Reading Material
How to evaluate formula passed as string in PHP?
parse_url
eval
Parse a URI String into Name-Value Collection
If you are looking for a way to achieve it without using an external library, the following code will help you.
public static Map<String, String> splitQuery(URL url) throws UnsupportedEncodingException {
Map<String, String> query_pairs = new LinkedHashMap<String, String>();
String query = url.getQuery();
String[] pairs = query.split("&");
for (String pair : pairs) {
int idx = pair.indexOf("=");
query_pairs.put(URLDecoder.decode(pair.substring(0, idx), "UTF-8"), URLDecoder.decode(pair.substring(idx + 1), "UTF-8"));
}
return query_pairs;
}
You can access the returned Map using <map>.get("client_id")
, with the URL given in your question this would return "SS".
UPDATE URL-Decoding added
UPDATE As this answer is still quite popular, I made an improved version of the method above, which handles multiple parameters with the same key and parameters with no value as well.
public static Map<String, List<String>> splitQuery(URL url) throws UnsupportedEncodingException {
final Map<String, List<String>> query_pairs = new LinkedHashMap<String, List<String>>();
final String[] pairs = url.getQuery().split("&");
for (String pair : pairs) {
final int idx = pair.indexOf("=");
final String key = idx > 0 ? URLDecoder.decode(pair.substring(0, idx), "UTF-8") : pair;
if (!query_pairs.containsKey(key)) {
query_pairs.put(key, new LinkedList<String>());
}
final String value = idx > 0 && pair.length() > idx + 1 ? URLDecoder.decode(pair.substring(idx + 1), "UTF-8") : null;
query_pairs.get(key).add(value);
}
return query_pairs;
}
UPDATE Java8 version
public Map<String, List<String>> splitQuery(URL url) {
if (Strings.isNullOrEmpty(url.getQuery())) {
return Collections.emptyMap();
}
return Arrays.stream(url.getQuery().split("&"))
.map(this::splitQueryParameter)
.collect(Collectors.groupingBy(SimpleImmutableEntry::getKey, LinkedHashMap::new, mapping(Map.Entry::getValue, toList())));
}
public SimpleImmutableEntry<String, String> splitQueryParameter(String it) {
final int idx = it.indexOf("=");
final String key = idx > 0 ? it.substring(0, idx) : it;
final String value = idx > 0 && it.length() > idx + 1 ? it.substring(idx + 1) : null;
return new SimpleImmutableEntry<>(
URLDecoder.decode(key, StandardCharsets.UTF_8),
URLDecoder.decode(value, StandardCharsets.UTF_8)
);
}
Running the above method with the URL
https://stackoverflow.com?param1=value1¶m2=¶m3=value3¶m3
returns this Map:
{param1=["value1"], param2=[null], param3=["value3", null]}
How do I parse a URL query parameters, in Javascript?
Today (2.5 years after this answer) you can safely use Array.forEach
. As @ricosrealm suggests, decodeURIComponent
was used in this function.
function getJsonFromUrl(url) {
if(!url) url = location.search;
var query = url.substr(1);
var result = {};
query.split("&").forEach(function(part) {
var item = part.split("=");
result[item[0]] = decodeURIComponent(item[1]);
});
return result;
}
actually it's not that simple, see the peer-review in the comments, especially:
- hash based routing (@cmfolio)
- array parameters (@user2368055)
- proper use of decodeURIComponent and non-encoded
=
(@AndrewF) - non-encoded
+
(added by me)
For further details, see MDN article and RFC 3986.
Maybe this should go to codereview SE, but here is safer and regexp-free code:
function getJsonFromUrl(url) {
if(!url) url = location.href;
var question = url.indexOf("?");
var hash = url.indexOf("#");
if(hash==-1 && question==-1) return {};
if(hash==-1) hash = url.length;
var query = question==-1 || hash==question+1 ? url.substring(hash) :
url.substring(question+1,hash);
var result = {};
query.split("&").forEach(function(part) {
if(!part) return;
part = part.split("+").join(" "); // replace every + with space, regexp-free version
var eq = part.indexOf("=");
var key = eq>-1 ? part.substr(0,eq) : part;
var val = eq>-1 ? decodeURIComponent(part.substr(eq+1)) : "";
var from = key.indexOf("[");
if(from==-1) result[decodeURIComponent(key)] = val;
else {
var to = key.indexOf("]",from);
var index = decodeURIComponent(key.substring(from+1,to));
key = decodeURIComponent(key.substring(0,from));
if(!result[key]) result[key] = [];
if(!index) result[key].push(val);
else result[key][index] = val;
}
});
return result;
}
This function can parse even URLs like
var url = "?foo%20e[]=a%20a&foo+e[%5Bx%5D]=b&foo e[]=c";
// {"foo e": ["a a", "c", "[x]":"b"]}
var obj = getJsonFromUrl(url)["foo e"];
for(var key in obj) { // Array.forEach would skip string keys here
console.log(key,":",obj[key]);
}
/*
0 : a a
1 : c
[x] : b
*/
How to parse a query string into a NameValueCollection in .NET
There's a built-in .NET utility for this: HttpUtility.ParseQueryString
// C#
NameValueCollection qscoll = HttpUtility.ParseQueryString(querystring);
' VB.NET
Dim qscoll As NameValueCollection = HttpUtility.ParseQueryString(querystring)
You may need to replace querystring
with new Uri(fullUrl).Query
.
How can I get query string values in JavaScript?
Update: Jan-2022
Using Proxy()
is faster than using Object.fromEntries()
and better supported
const params = new Proxy(new URLSearchParams(window.location.search), {
get: (searchParams, prop) => searchParams.get(prop),
});
// Get the value of "some_key" in eg "https://example.com/?some_key=some_value"
let value = params.some_key; // "some_value"
Update: June-2021
For a specific case when you need all query params:
const urlSearchParams = new URLSearchParams(window.location.search);
const params = Object.fromEntries(urlSearchParams.entries());
Update: Sep-2018
You can use URLSearchParams which is simple and has decent (but not complete) browser support.
const urlParams = new URLSearchParams(window.location.search);
const myParam = urlParams.get('myParam');
Original
You don't need jQuery for that purpose. You can use just some pure JavaScript:
function getParameterByName(name, url = window.location.href) {
name = name.replace(/[\[\]]/g, '\\$&');
var regex = new RegExp('[?&]' + name + '(=([^]*)|&|#|$)'),
results = regex.exec(url);
if (!results) return null;
if (!results[2]) return '';
return decodeURIComponent(results[2].replace(/\+/g, ' '));
}
Usage:
// query string: ?foo=lorem&bar=&baz
var foo = getParameterByName('foo'); // "lorem"
var bar = getParameterByName('bar'); // "" (present with empty value)
var baz = getParameterByName('baz'); // "" (present with no value)
var qux = getParameterByName('qux'); // null (absent)
NOTE: If a parameter is present several times (?foo=lorem&foo=ipsum
), you will get the first value (lorem
). There is no standard about this and usages vary, see for example this question: Authoritative position of duplicate HTTP GET query keys.
NOTE: The function is case-sensitive. If you prefer case-insensitive parameter name, add 'i' modifier to RegExp
NOTE: If you're getting a no-useless-escape eslint error, you can replace name = name.replace(/[\[\]]/g, '\\$&');
with name = name.replace(/[[\]]/g, '\\$&')
.
This is an update based on the new URLSearchParams specs to achieve the same result more succinctly. See answer titled "URLSearchParams" below.
URL query parameters to dict python
Use the urllib.parse
library:
>>> from urllib import parse
>>> url = "http://www.example.org/default.html?ct=32&op=92&item=98"
>>> parse.urlsplit(url)
SplitResult(scheme='http', netloc='www.example.org', path='/default.html', query='ct=32&op=92&item=98', fragment='')
>>> parse.parse_qs(parse.urlsplit(url).query)
{'item': ['98'], 'op': ['92'], 'ct': ['32']}
>>> dict(parse.parse_qsl(parse.urlsplit(url).query))
{'item': '98', 'op': '92', 'ct': '32'}
The urllib.parse.parse_qs()
and urllib.parse.parse_qsl()
methods parse out query strings, taking into account that keys can occur more than once and that order may matter.
If you are still on Python 2, urllib.parse
was called urlparse
.
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