I have a signup.jsp page, there are some input boxes of html on this page, there is a input box for email-id also, when i submit form after fill up there is server side checking of email address, if email address already exist in database then signup.jsp page will redered again, then i want all the value should be dispalyed in all the input boxes that the user filled before submitting the form.
Appropriate help will be appreciable...
<input type="text" name="email" value="<c:out value='${param.email}'/>"/>
This displays the value of the email request parameter in the email text box. Initially, this parameter won't exist, so the text box will be blank.
Note the use of the <c:out> JSTL tag, which allows HTML-escaping the value of the parameter.
Your form parameters should be wrapped in a element. When submitted they will be sent to server using request parameters.
Then in your jsp file you need to render those request parameters in the places they should appear. Initially they will be empty, so user will see them rendered as initial blank values to fill.
The better approach is that you have to create a bean with session scope using <jsp:useBean/>, on server code update the bean's attributes and in view (jsp) page embed bean's property value to the <input/> attributes.
<form method='post' action='your_action'>
<input type='text' value="<c:out value='${bean.name}'/>" name='name'/>
</form>
Related
I have some HTML forms and I need to provide additional parameters which the user will not fill up in the form UI. I understand I can do it using query parameters or hidden form fields. Examples :
a form whose data must be submitted to the server together with an option chosen in the previous web page
Ex: URL /createImage?option=option_value (accessible via GET by user) would contain the HTML code below
Query parameter
<form action='/createImage?option=option_value'>
<input type='textfield1' name='var1'>
</form>
Hidden field
<form action='/createImage'>
<input type='hidden' name='option' value='option_value'>
<input type='textfield1' name='var1'>
</form>
(in this case, I suppose a third solution would be to use a HTTP session variable instead)
a fake form used to associate a POST HTTP request with a image.
Query parameter
<form action='/createContainer?image=image1'>
<input type='image' src='container.png'>
</form>
Hidden field
<form action='/createContainer'>
<input type='hidden' name='image' value='image1'>
<input type='image' src='container.png'>
</form>
(in this case, I suppose a third solution would be to use a standard img HTML tag and use Javascript to send the POST request to the server on its click() event)
Are there any upsides/downsides in each one of those approaches or is it just a matter of personal preference?
Sometimes I see a form that is wrapped in a form tag
<form action="demo_form.asp" method="get">
First name: <input type="text" name="fname"><br>
Last name: <input type="text" name="lname"><br>
<input type="submit" value="Submit">
</form>
And sometimes there is no form tag, but just a div
<div class="view">
<input class="toggle" type="checkbox">
<button class="destroy"></button>
</div>
<input class="edit" value="<%= title %>">
How come sometimes the form tag is present and other times its not for forms?
Prior to submitting information via AJAX, HTML forms were the standard in sending information to a server from a web page. They include the destination and method in the form attributes. More recently, this can be handled without assigning these attributes in form and sent via Javascript; typically using AJAX. This means the form element isn't necessary but is a good idea to include where possible to be syntactically correct HTML.
The <form> tag is not used specially when developers decide not to submit data in a conventional manner. The <form> tag has the main purpose of wrapping all the inputs that will be submitted to the next page specified on the action attribute of the <form> tag, and these data is sent using either POST or GET method indicated with the method attribute.
<form action="nextpage.php" method="post">
When the inputs are not wrapped by a <form>tag it means that the data is never submitted to another page or it submitted in a different way through javascript.
JavaScript is able to read the values of all the inputs and submit this data to a next page simulating a form or simply send it to the server without changing the page, when the page never changes but the data is sent to the server is when we say it was submitted using AJAX.
Forms input types are not always used to send values, they could be use as controllers, like date difference purposes, ranges or sliders to control alpha chanel, or rotate and image, making calculators, showing or hiding stuff on the page, lots of purposes other than just submitting to other pages
Check this code for a calculator on one of posts couple hours ago, lots of buttons, but not submitting anything
<INPUT TYPE="button" ID="button-cos" VALUE="cos">
Another example using button and input type="text" online image editor tutorial
I was always confused about what the 'name' attribute did in html forms. From the textbook I read (html and css, design and build webpages by John Duckett), this is what it said about the 'name' attribute.
When users enter information
into a form, the server needs to
know which form control each
piece of data was entered into.
(For example, in a login form, the
server needs to know what has
been entered as the username
and what has been given as the
password.) Therefore, each form
control requires a name attribute.
The value of this attribute
identifies the form control and is
sent along with the information
they enter to the server.
From reading this, I always thought that, say in the database there is a field called "theUsersPasswordField" and a field called "theUsersUsernameField". I thought that, suppose there is a registration form, then the form would be like:
<form action="aURL" method="post">
<p>Please enter what you want your Username to be:</p>
<input type="submit" name="theUsersUsernameField" />
<p>Please enter what you want your Password to be:</p>
<input type="password" name="theUsersPasswordField" />
</form>
and then this way, when the information is sent to the database, it will know which information to put in the 'theUsersPasswordField" and which information to put in the "theUsersUesrnameField". Am I wrong?
What does name="next" mean? I see it often when I look at html forms, for example, here in this Django tutorial I am doing:
<form method="post" action=".">
<p><label for="id_username">Username:</label></p>
<p><label for="id_password">Password:</label></p>
<input type="hidden" name="next" value="/" />
<input type="submit" value="login" />
</form>
In the tutorial I am doing, it says that
The html form contains a submit button and a hidden
field called next. This hidden variable contains a URL that tells the view where to
redirect the user after they have successfully logged in
now, how is 'next' a url? When I run the code, the form does in fact successfully redirect to the main page, but how does it know to redirect to the main page? Why does name='next'?
And how does the server know which information to treat as the username and which information to treat as the password? I though that that is what the 'name' attribute is used for?
The name attribute in a control element like input assigns a name to the control. It has two basic effects: 1) a control needs a name in order to be “successful”, which means that a name=value pair from it will be included into the form data when the form is submitted; and 2) the attribute specifies what will be included as the first part of the name=value pair.
It is entirely up to the server-side form handler what (if anything) it will do with the name=value pairs in the form data. They might have a simple correspondence in some database, but that’s just one possibility. And form handling need not be database-based at all.
The name attribute values have no predefined meaning in HTML. They are just strings selected for use in this context, and they may be descriptive or mnemonic, or they may not.
However, the choice of name attribute values may have side effects. Browsers may give the user a menu of previously entered data so that if you fill e.g. several forms (possibly in different sites) that have a control named email, you might be able to enter your email address just once and then accept whatever the browser suggests as input. This may be seen as a convenience or as a threat to data security. There is proposed set of “standard” names for many purposes in HTML5 CR.
For completeness, it needs to be added that in browser practice and according to HTML5 CR description of name, two names have a special meaning: _charset_ and isindex.
The name next is in no way special, but in this context, it appears to specify the next page to move to. It is defined for a hidden field, so it takes effect independently of user input.
and then this way, when the information is sent to the database, it will know which information to put in the 'theUsersPasswordField" and which information to put in the "theUsersUesrnameField". Am I wrong?
You have to write a script (for example in php) that will put the right values from your form (they are in the $_POST array) into the databse.
in your example $_POST['theUsersUsernameField'] will hold the username
<form method="post" action=".">
<p><label for="id_username">Username:</label></p>
<p><label for="id_password">Password:</label></p>
<input type="hidden" name="next" value="/" />
<input type="submit" value="login" />
</form>
how is 'next' a url?
next is not the url.
the action="." is the url to wich the form redirects.
/ is the value that the script will evaluate to see what it has to do. (Normally you will have to change this into something else like 'check password')
In the $_POST[] array there will be a key $_POST['next'] and the value will be /
I am not familiar with Django but I hope this helps
<input name="price" id="asdprice" value="" type="text">
I do not wish to use any JS if possible
As you can see the value field is empty, and I do not want to prefill it as it will be submitable.
What I want is a prefilled text area, with lets say
http://www.
as i would like that to be a valid format for that field, normally such filled input will be less opaque.
You can display a hint for the user to enter a valid URI using an input placeholder attribute:
<input name="price" id="adsprice" type="text" placeholder="http://">
However the placeholder text will disappear once the field comes into focus. You should be aware that users will enter all kinds of rubbish into form fields, so always validate the input on the server-side and prepend the http:// if it's missing.
BTW, there are valid URIs that do not begin with http://www. and not all sites redirect the www. subdomain as you would expect.
I have found an entry in html file
'<form action="?" ... '
I do not understand what it does.
Search in Google returned no results. Actually it is a Django template file, but I didn't find anything in django template documentation.
It uses the current URL with an empty query string as the action of the form. An empty query string. Empty. Meaning no query string at all. The query string will be no more. It will not be used. It will be gone. There will be no more query string after submitting the form. The query string will have vanished. Disappeared. Gone away. Become no more.
The action= atrribute has only value. i.e URL.
In simple english once your form is processed and you hit a submit button or enter you will be redirected to the URL you give to the action attribute
Example:
<form action="demo_form.asp" method="get">
First name: <input type="text" name="fname"><br>
Last name: <input type="text" name="lname"><br>
<input type="submit" value="Submit">
</form>
In the case of you question, if the action is "?" then the returned hash-string will be current URL plus "/?" appended which will take you back to the same page you were on.
action="" will resolve to the page's address. action="?" will resolve to the page's address + ?, which will mean an empty fragment identifier.
Doing the latter might prevent a navigation (new load) to the same page and instead try to jump to the element with the id in the fragment identifier. But, since it's empty, it won't jump anywhere.
Usually, authors just put # in href-like attributes when they're not going to use the attribute where they're using scripting instead. In these cases, they could just use action="" (or omit it if validation allows).
'<form action="?" ... ' strips the query string off of the URL when submitting the form, and submits the form to the current document address (i.e. itself).
Here is what that means:
Let's use the following URL as example:
ExampleSite.com**?SearchTerm1=chocolate&SearchTerm2=cake**
This URL contains the query string
'?SearchTerm1=chocolate&SearchTerm2=cake'
and sends that query string to the web site server, attached to the URL.
Sometimes, you want to ensure that the URL being passed to the server is stripped of any query strings (i.e. the query is string is removed completely) and only the URL is passed.
Let's say you bookmarked the page, using the full URL and query string ExampleSite.com?SearchTerm1=chocolate&SearchTerm2=cake****
Now you get to that page, and there is a search form.
You decide to use the search form to search for something new...
'<form action="?" ... ', as used above, removes the query string from the URL when the form is submitted, and submits the form to the same page that it came from (usually a 'controller' (a page with programming that determines what to do with the information sent to it by the user) ).
<form name="test" action="process.php" method="get">
<input type="submit" value="Submit">
The action used here will take you to the process.php page after clicking the submit button.
In short the action= is used to go to the specified page(mentioned in the action=) after filling the form and submitting.
When we don't know the url to go by submit the form we can specify
like this, It will reload the same page by appending question mark(?)
to url.
I.e, Form is submitted for same page itself. It identifies
form is reloaded.
Note: We can leave action property blank, even though it will work!
action is an attribute used in forms to specify the URL of the file that will process the input control when form is submitted