Re: Access hidden fields array

[Tobias Soloschenko]

Hi,

thanks a lot for the clarification. I changed the implementation to access the 
parameter with brackets, now. Everything is working like expected.

kind regards

Tobias
-
To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org
For additional commands, e-mail: users-h...@tomcat.apache.org

Re: Access hidden fields array

[Christopher Schultz]

-BEGIN PGP SIGNED MESSAGE-
Hash: SHA256

Tobias,

On 5/3/17 6:48 AM, Tobias Soloschenko wrote:
> The reason why I used the brackets was that in some cases
> (browsers) only the first value was returned. (Even if there were
> more then one hidden field with that name)

This is incorrect. Browsers don't have a high-level API for
manipulating URLs, parameters, etc. If you are using a toolkit, it may
add these restrictions, but the browser has nothing to do with it.

> Also mentioned here: http://stackoverflow.com/a/6547234 - PHP is
> also resolving the variable without brackets.

PHP uses the "[]" suffix to indicate that a parameter name is expected
to have multiple values, and expose those values to the PHP script as
an array (instead of returning e.g. only the first value encountered).

> There are various other questions at stackoverflow mentioning to
> get the variable without brackets:
> 
> http://stackoverflow.com/questions/6547209/passing-array-using-html-fo
rm-hidden-element
>
> 
http://stackoverflow.com/questions/4237090/how-to-pass-array-through-hid
den-field
> http://stackoverflow.com/questions/29076219/javascript-storing-array-o
f-objects-in-hidden-field
>
>  Don't know if this should be supported.

The servlet spec is clear: the name of the parameter is the name of
the parameter from the HTTP request. If you decide to name your
parameter "array[]", then you must access it using "array[]".

If you want to use a framework that adds that kind of interpretation,
you are welcome to do so, but Tomcat will never add anything like that.

- -chris
-BEGIN PGP SIGNATURE-
Comment: GPGTools - http://gpgtools.org
Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/
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=H+SQ
-END PGP SIGNATURE-

-
To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org
For additional commands, e-mail: users-h...@tomcat.apache.org

Re: Access hidden fields array

[tomcat]

Hi again.

First, on this list please do not top-post.
See : http://tomcat.apache.org/lists.html#tomcat-users
  Important --> 6

I have reformated your message according to that.
>

2017-05-03 12:05 GMT+02:00 André Warnier (tomcat) :


On 03.05.2017 11:23, Tobias Soloschenko wrote:


Hello everyone,

I just updated to tomcat 8.0.43 and I noticed a special behavior I want to
discuss. (I don't know if this only occurs with this version)

When I add two hidden fields within a form like:






I just thought to access the parameter values within the java api like

String[] myArray = httpServletRequest.getParameterValues("array");


In my case however I just can access them like (with brackets):

String[] myArray = httpServletRequest.getParameterValues("array[]");


This also applies to httpServletRequest.getParameterMap().containsKey


Is this an expected behavior?




I would tend to say : yes, it is expected.
(This also has nothing to do with tomcat per se, and is more of the domain
of the HTML and HTTP specifications).

I have not checked the relevant HTML/HTTP specs to verify which characters
precisely are allowed in the "name" attribute of a HTML  field.
But assuming that "[" and "]" /are/ allowed in such attributes, then that
is the name under which the value of this parameter will be sent by the
browser to the server.

More precisely : if you have in your form an  element such as :



(whatever "xyz[123abc]" may be, in terms of valid characters)
then "xyz[123abc]" is the name/label of this parameter, and the browser
will send the corresponding input field value to the server as something
like :

xyz[123abc]=1

The fact that this label /resembles/ the way in which you would invoke an
array in Java (or any other server-side programming language) is pure
coincidence.

In other words again, in your above example, if you replaced "array[]" by
"array][" (or "array)(", or "array(xyz)" or "variable#1") everywhere, it
would work just the same. It's just a label.

And the fact that in your example they are seen as an array on the java
side, is just because there is more than one value sent by the browser with
that same label, and the POST parsing logic on the server side then makes
this into an array of values.

This all being said, I would not name any input fields in a form with a
name like "array[]". That is bound to create confusion, as you yourself can
now attest.
You can name is "ferrari" instead; but that does not mean that on the
server side, you should expect something red with 4 wheels and 12 cylinders.




On 03.05.2017 12:48, Tobias Soloschenko wrote:

Hi,

thanks for the detailed answer.

The reason why I used the brackets was that in some cases (browsers) only
the first value was returned. (Even if there were more then one hidden
field with that name)

Also mentioned here: http://stackoverflow.com/a/6547234 - PHP is also
resolving the variable without brackets.

There are various other questions at stackoverflow mentioning to get the
variable without brackets:

http://stackoverflow.com/questions/6547209/passing-array-using-html-form-hidden-element
http://stackoverflow.com/questions/4237090/how-to-pass-array-through-hidden-field
http://stackoverflow.com/questions/29076219/javascript-storing-array-of-objects-in-hidden-field

Don't know if this should be supported.



There is something confusing in your posts so far.
This is a Tomcat user's list. Tomcat is a Java Servlet Engine, written in Java.
Your example above also seemed to be Java.
But the links you propose above all relate to PHP applications, and they are a bit 
confusing (and sometimes also confused) themselves.
I mean, there is some information in them that may be relevant to your issue, but also a 
lot of noise that is irrelevant here.


There are 3 parts to your issue :
1) how the HTML form is generated, before it is sent to the browser
2) once it is "in" the browser, what the  looks like (in terms of input fields and 
values), and how its content will be sent to the server when the user presses the submit 
button
3) the application, on the server side, which will parse this POST content, and how the 
data will look to it


Only (3) is really relevant on this list.

And as far as that is concerned :

A) if your  contains 3 input elements like
 
 
 

then what the browser sends to the server (in one way or another), will look 
like

f1=1
f1=2
f1=3

and, in a Java application on the server, to get these values you would use 
something like :

String[] myArray = httpServletRequest.getParameterValues("f1");

and in myArray, you would get [ "1", "2", "3" ]

and this is true whatever the name "f1" would be replaced by, in the  as well as in 
the Java code.


B) if your  contains 3 input elements like




then what the browser sends to the server (in one way or another), will look 
like

f1=1
f2=2
f3=3

then, in the Java application on the server, if you use something like :

String[] myArray = 

Re: Access hidden fields array

[Tobias Soloschenko]

Hi,

thanks for the detailed answer.

The reason why I used the brackets was that in some cases (browsers) only
the first value was returned. (Even if there were more then one hidden
field with that name)

Also mentioned here: http://stackoverflow.com/a/6547234 - PHP is also
resolving the variable without brackets.

There are various other questions at stackoverflow mentioning to get the
variable without brackets:

http://stackoverflow.com/questions/6547209/passing-array-using-html-form-hidden-element
http://stackoverflow.com/questions/4237090/how-to-pass-array-through-hidden-field
http://stackoverflow.com/questions/29076219/javascript-storing-array-of-objects-in-hidden-field

Don't know if this should be supported.

kind regards

Tobias

2017-05-03 12:05 GMT+02:00 André Warnier (tomcat) :

> On 03.05.2017 11:23, Tobias Soloschenko wrote:
>
>> Hello everyone,
>>
>> I just updated to tomcat 8.0.43 and I noticed a special behavior I want to
>> discuss. (I don't know if this only occurs with this version)
>>
>> When I add two hidden fields within a form like:
>>
>> 
>>
>> 
>>
>>
>> I just thought to access the parameter values within the java api like
>>
>> String[] myArray = httpServletRequest.getParameterValues("array");
>>
>>
>> In my case however I just can access them like (with brackets):
>>
>> String[] myArray = httpServletRequest.getParameterValues("array[]");
>>
>>
>> This also applies to httpServletRequest.getParameterMap().containsKey
>>
>>
>> Is this an expected behavior?
>>
>>
>>
> I would tend to say : yes, it is expected.
> (This also has nothing to do with tomcat per se, and is more of the domain
> of the HTML and HTTP specifications).
>
> I have not checked the relevant HTML/HTTP specs to verify which characters
> precisely are allowed in the "name" attribute of a HTML  field.
> But assuming that "[" and "]" /are/ allowed in such attributes, then that
> is the name under which the value of this parameter will be sent by the
> browser to the server.
>
> More precisely : if you have in your form an  element such as :
>
> 
>
> (whatever "xyz[123abc]" may be, in terms of valid characters)
> then "xyz[123abc]" is the name/label of this parameter, and the browser
> will send the corresponding input field value to the server as something
> like :
>
> xyz[123abc]=1
>
> The fact that this label /resembles/ the way in which you would invoke an
> array in Java (or any other server-side programming language) is pure
> coincidence.
>
> In other words again, in your above example, if you replaced "array[]" by
> "array][" (or "array)(", or "array(xyz)" or "variable#1") everywhere, it
> would work just the same. It's just a label.
>
> And the fact that in your example they are seen as an array on the java
> side, is just because there is more than one value sent by the browser with
> that same label, and the POST parsing logic on the server side then makes
> this into an array of values.
>
> This all being said, I would not name any input fields in a form with a
> name like "array[]". That is bound to create confusion, as you yourself can
> now attest.
> You can name is "ferrari" instead; but that does not mean that on the
> server side, you should expect something red with 4 wheels and 12 cylinders.
>
>
> -
> To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org
> For additional commands, e-mail: users-h...@tomcat.apache.org
>
>

Re: Access hidden fields array

[tomcat]

On 03.05.2017 11:23, Tobias Soloschenko wrote:

Hello everyone,

I just updated to tomcat 8.0.43 and I noticed a special behavior I want to
discuss. (I don't know if this only occurs with this version)

When I add two hidden fields within a form like:






I just thought to access the parameter values within the java api like

String[] myArray = httpServletRequest.getParameterValues("array");


In my case however I just can access them like (with brackets):

String[] myArray = httpServletRequest.getParameterValues("array[]");


This also applies to httpServletRequest.getParameterMap().containsKey


Is this an expected behavior?




I would tend to say : yes, it is expected.
(This also has nothing to do with tomcat per se, and is more of the domain of the HTML and 
HTTP specifications).


I have not checked the relevant HTML/HTTP specs to verify which characters precisely are 
allowed in the "name" attribute of a HTML  field.
But assuming that "[" and "]" /are/ allowed in such attributes, then that is the name 
under which the value of this parameter will be sent by the browser to the server.


More precisely : if you have in your form an  element such as :



(whatever "xyz[123abc]" may be, in terms of valid characters)
then "xyz[123abc]" is the name/label of this parameter, and the browser will send the 
corresponding input field value to the server as something like :


xyz[123abc]=1

The fact that this label /resembles/ the way in which you would invoke an array in Java 
(or any other server-side programming language) is pure coincidence.


In other words again, in your above example, if you replaced "array[]" by "array][" (or 
"array)(", or "array(xyz)" or "variable#1") everywhere, it would work just the same. It's 
just a label.


And the fact that in your example they are seen as an array on the java side, is just 
because there is more than one value sent by the browser with that same label, and the 
POST parsing logic on the server side then makes this into an array of values.


This all being said, I would not name any input fields in a form with a name like 
"array[]". That is bound to create confusion, as you yourself can now attest.
You can name is "ferrari" instead; but that does not mean that on the server side, you 
should expect something red with 4 wheels and 12 cylinders.



-
To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org
For additional commands, e-mail: users-h...@tomcat.apache.org

Access hidden fields array

[Tobias Soloschenko]

Hello everyone,

I just updated to tomcat 8.0.43 and I noticed a special behavior I want to
discuss. (I don't know if this only occurs with this version)

When I add two hidden fields within a form like:






I just thought to access the parameter values within the java api like

String[] myArray = httpServletRequest.getParameterValues("array");


In my case however I just can access them like (with brackets):

String[] myArray = httpServletRequest.getParameterValues("array[]");


This also applies to httpServletRequest.getParameterMap().containsKey


Is this an expected behavior?


kind regards and thanks in advance

Tobias