I know this post is really old, but I have to reply because although BalusC's answer is marked as correct, it's not completely correct.
You have to write the query adding "[]" to foo like this:
foo[]=val1&foo[]=val2&foo[]=val3
I know this post is really old, but I have to reply because although BalusC's answer is marked as correct, it's not completely correct.
You have to write the query adding "[]" to foo like this:
foo[]=val1&foo[]=val2&foo[]=val3
That depends on what the target server accepts. There is no definitive standard for this. See also a.o. Wikipedia: Query string:
While there is no definitive standard, most web frameworks allow multiple values to be associated with a single field (e.g.
field1=value1&field1=value2&field2=value3).[4][5]
Generally, when the target server uses a strong typed programming language like Java (Servlet), then you can just send them as multiple parameters with the same name. The API usually offers a dedicated method to obtain multiple parameter values as an array.
foo=value1&foo=value2&foo=value3
String[] foo = request.getParameterValues("foo"); // [value1, value2, value3]
The request.getParameter("foo") will also work on it, but it'll return only the first value.
String foo = request.getParameter("foo"); // value1
And, when the target server uses a weak typed language like PHP or RoR, then you need to suffix the parameter name with braces [] in order to trigger the language to return an array of values instead of a single value.
foo[]=value1&foo[]=value2&foo[]=value3
_GET["foo"]; // [value1, value2, value3]
echo is_array($foo); // true
In case you still use foo=value1&foo=value2&foo=value3, then it'll return only the first value.
_GET["foo"]; // value1
echo is_array($foo); // false
Do note that when you send foo[]=value1&foo[]=value2&foo[]=value3 to a Java Servlet, then you can still obtain them, but you'd need to use the exact parameter name including the braces.
String[] foo = request.getParameterValues("foo[]"); // [value1, value2, value3]
Array Parameter in GET request
Sending Array Of Objects in GET request (axios)
How to pass array as a parameter
HTTP request with array body parameter
Here's what I figured out:
Submitting multi-value form fields, i.e. submitting arrays through GET/POST vars, can be done several different ways, as a standard is not necessarily spelled out.
Three possible ways to send multi-value fields or arrays would be:
?cars[]=Saab&cars[]=Audi(Best way- PHP reads this into an array)?cars=Saab&cars=Audi(Bad way- PHP will only register last value)?cars=Saab,Audi(Haven't tried this)
Form Examples
On a form, multi-valued fields could take the form of a select box set to multiple:
<form>
<select multiple="multiple" name="cars[]">
<option>Volvo</option>
<option>Saab</option>
<option>Mercedes</option>
</select>
</form>
(NOTE: In this case, it would be important to name the select control some_name[], so that the resulting request vars would be registered as an array by PHP)
... or as multiple hidden fields with the same name:
<input type="hidden" name="cars[]" value="Volvo">
<input type="hidden" name="cars[]" value="Saab">
<input type="hidden" name="cars[]" value="Mercedes">
NOTE: Using field[] for multiple values is really poorly documented. I don't see any mention of it in the section on multi-valued keys in Query string - Wikipedia, or in the W3C docs dealing with multi-select inputs.
UPDATE
As commenters have pointed out, this is very much framework-specific. Some examples:
Query string:
?list_a=1&list_a=2&list_a=3&list_b[]=1&list_b[]=2&list_b[]=3&list_c=1,2,3
Rails:
"list_a": "3",
"list_b":[
"1",
"2",
"3"
],
"list_c": "1,2,3"
Angular:
"list_a": [
"1",
"2",
"3"
],
"list_b[]": [
"1",
"2",
"3"
],
"list_c": "1,2,3"
(Angular discussion)
See comments for examples in node.js, Wordpress, ASP.net
Maintaining order: One more thing to consider is that if you need to maintain the order of your items (i.e. array as an ordered list), you really only have one option, which is passing a delimited list of values, and explicitly converting it to an array yourself.
A query string carries textual data so there is no option but to explode the array, encode it correctly and pass it in a representational format of your choice:
p1=value1&pN=valueN...
data=[value1,...,valueN]
data={p1:value1,...,pN:valueN}
and then decode it in your server side code.
I'm implementing filter, sorting, pagination and search functionality via API call. For filter values i have to send array of objects in parameters.
Now I know when we want to send complex params in query we use POST method. But still wants to understand.
In my application, swagger stringify does it without any issue. I can't get the same format which is as below.
e g. This is i want in request headers (payload)
filter:[{name:"descriptive", value: "test"}]
I have tried qs package and JSON.stringify
qs.stringify(params)
or with arrayFormat but not getting the above format in payload.
Instead I'm getting this, which is not acceptable
filter[0][name]: descriptive
filter[0][value]: test
any help would be appreciated.