Im trying to get the values of some td elements where the data consist of data from MySQL table. It displays the data fine in my browser (e.g. if i change type from "hidden" to "submit"), but when I try to get the value i only get null.
Here are my jsp and it displays the correct results in the browser.
<td>
<form action="history.jsp" method="get">
<input type="hidden" name="res" value="<%=his.getRes()%>"/>
</form>
</td>
When i try to print the values however, I only get "null" at of evey :
<%
String res = request.getParameter("res");
System.out.print(res);
%>
I'm still very new, so it's proberly a straight forward answer. Thank you in advance for the help.
I suggest that you change the name of your variable :
String newname = request.getParameter("res");
System.out.println(newname)
One can submit (=send) only one <form>. So one must assume there is just one single td with one <form>. Forms also may not be nested in an outer form.
It need some way to submit the form.
So experiment first with:
<td>
<form action="history.jsp" method="get">
<input type="text" name="res" value="<%=his.getRes()%>"/>
<input type="submit" value="Send"/>
</form>
</td>
This will show whether his.getRes() yielded something. And allows a manual submit in the browser.
Related
i have one view where i m showing many records and now i m adding functionality for user to download those records which he will choose date from search textbox. As my search textbox in jsp outside of form tag and thus i m not getting the value of that parameter in my servlet..is there any way to get that value from outside of form tag? Here is my jsp
<div id="divOfDateTable">
Search:<input type="text" name="dropdown" id="datedropdown">
<button id="dateButton" name="dateSearch">Search</button>
</div>
<form action="Download_Servlet" class="download" method="post">
<input type="submit" id="downloadRecords" value="Download Order-records">
</form>
In my Servlet i want to get that parameter value.i.e;Date put by user.As per the requirement only the searched records by the user needs to be downoaded. So please guys help out..
I have a JSP page which reads data from HTML and has CSS,Jquery code in it .
Now my webpage in jsp has two text labels and a add button next to them.
User can enter any no of values in the text field.
Now my requirement is that every time user enters the alue in these fields and clicks on add then that data should be passed on to my servlet. Servlet will basically do some validation and return a boolean variable.
Based on the value of this boolean, I shall change the appearance of my text boxes.
This is required to be done for every time user clicks on Add button.
How can I achieve this ?
My HTML code :
<div id="id1" name="id1" style="display: none;">Add a node: </br>
<input type="text" name="ipaddress" id="ipaddress" placeholder="Enter Node IP"> <input type="text" name="port" id="port" placeholder="Enter Node Port">
<input type="button" value="Add" name="addnodebutton" id="addnodebutton"/>
</div>
The value in ipaddress and port shall be passed on to my servlet and depending on return parameter, their appearance should change.
Can anyone enlighten me how this is actually going to work ?
TIA :)
For passing data to and from a servlet, you have options.
Option 1- You can wrap your html in a form tag and set the action/method properties for your servlet/http method like below:
<form method="POST" action="servletname">
<input type="text" name="ipaddress" id="ipaddress" placeholder="Enter Node IP">
<input type="text" name="port" id="port" placeholder="Enter Node Port">
<input type="submit" value="Add" name="addnodebutton" id="addnodebutton"/>
</form>
The submit would send a request with the input to your servlet. You would then need to handle your request parameters in your servlet, set your values/flags in your response object and forward to the user or jsp/html page of your choice.
Option 2- You can make an ajax call from your jsp, process your input and return a response to your page asynchronously. Example below:
A Simple AJAX with JSP example
I have a table that is dynamically created that has rows of movies.
It has a title column,
a media type column,
a rating column,
and a column that contains a "view" button.
When one of these view buttons is clicked,
I would like to go to a page that contains all the details of that movie by sending the title to the controller so I can query for it in mySql.
The problem is that for all these buttons,
the value is always going to be "view".
So my solution is to make the name of the button different as shown in the code below (this is the raw html generated from the jsp):
<html>
<body>
<form action="someAction">
<table>
<tr>
<th>title</th>
<th>type</th>
<th>rating</th>
</tr>
<tr>
<td>title1</td>
<td>DVD</td>
<td>R</td>
<td><input type="submit" name="mediaType.title1" value="view"></td>
</tr>
<tr>
<td>title2</td>
<td>DVD</td>
<td>R</td>
<td><input type="submit" name="mediaType.title2" value="view"></td>
</tr>
<tr>
<td>title3</td>
<td>BLU-RAY</td>
<td>PG-13</td>
<td><input type="submit" name="mediaType.title3" value="view"></td>
</tr>
</table>
</form>
</body>
</html>
I could then use a parameterMap to figure out which view was pressed.
That is messy and Spring has to have some way of being able to do this.
I thought something like this would work in the controller:
#RequestMapping("someAction", params = "mediaType.{title}=view")
public ModelAndView loadPage(String title) {
// use title to query mysql
// build Model
// return ModelAndView
}
However this doesn't work.
Is there something that I can use in Spring that would be simpler and cleaner like above instead of getting the parameterMap from the request?
If I'm understanding this correctly, you have rows of information organized into a table. You're looping through some kind of collection, which has the side effect of making each input field have similar 'name' attributes. As a result, it's difficult to determine which input fields you really care about. You've then chosen to use the button as an identifier (presumably, because only the one button you actually click on get's added to the request -all the others don't get submitted) to determine which 'row', and subsequent input fields.
I think this might all come down to which 'button' you're using. If you're using a literal input tag (type="submit" or "button") the 'value' attribute is what the user sees as the text on the button -so, you're forced to play shenanigans with the 'name' attribute (presumably by adding an index to the name, splitting the string once you get it out of the request, and using that identifier to get the other parameters out of the request that also have the same identifier appended to their 'name' attribute).
JSP
<input type="submit" name="view${varStatus.index}" value="View" />
HTML Source
<input type="submit" name="view3" value="View">
You should probably use the button tag instead. It allows the text that the user sees to be different than the value that is submitted in the request.
JSP
<button type="submit" name="view" value="${varStatus.index}" >View</button>
HTML Source
<button type="submit" name="view" value="3">View</button>
This gives you the 'identifier' for the row.
How Spring fits into this:
I played with the #RequestMapping and the #RequestParam annotations, and was unable to get Spring to give me the values directly into the controller. But, I was able to do it by writing a custom HandlerMethodArgumentResolver along with a custom annotation.
note: I'm using annotations and java config instead of xml config, AND probably more importantly -this was a quick and dirty example to get it working. adjust it as needed for your situation.
HandlerMethodArgumentResolver
Annotation
Controller method
Instead of putting the table inside one form, you could put multiple forms inside the table, in the TRs:
<tr>
<form action="someAction">
<td>title1<input type='hidden' name='title' value='title1' /></td>
<td>DVD</td>
<td>R</td>
<td><input type="submit" value="view"></td>
</form>
</tr>
Then each title has its own form and you send in the title (always with parameter name of title) from a hidden input.
The solution lies in this statement:
"I have a table that is dynamically created that has rows of movies".
Presumably,
you are looping through a list of movies and generating the table in the jsp file and each row has some unique identifier.
Add a hidden to identify the selected row.
Set the value of the hidden value in an onclick handler from the submit buttons.
Here is some example stuff:
<form ...>
<c:forEach blah var="row">
<tr>
...
<td><input type="submit" value="View" onclick="setSelectedRow('${row.id}')"/></td>
</c:forEach>
<input type="hidden" id="blammy" name="blammy" value=""/>
</form>
<script type="text/javascript">
function setSelectedRow(rowId)
{
... set blammy.value equal to rowId.
}
</script>
// the id is used by JavaScript to find the object in the DOM.
// the name is what appears in the request.
#RequestMapping("someAction")
public ModelAndView loadPage(
#RequestParameter("blammy") final String blammy)
{
...
}
Is there a way to get the name of the form element itself using JSP? I searched google and did not find any examples which show how to get the name of the form value specified in the JSP file.
For example, I have the below form,
<html>
<form name="register" action="servregister" method="POST"
onsubmit="return validate();">
</form>
</html>
I would like to get the string "register" to a string variable in JSP. Is there a way to do this?
No, a <form> is not submitted with the request. Instead create a hidden input element which holds that information.
<input type="hidden" name="name of form" value="value" />
or possibly the submit element
<input type="submit" name="distinguishing name" value="submit" />
Either of these in a form with be sent as a url-encoded parameter.
There is probably a better solution to what you are trying to do if you explain your goals.
Consider looking into different patterns for achieving your goals.
I have a question on how to update a particular record in a database using JSTL and java servlets.
Ok to call one record, I use a servlet to run a query to populate a jsp page using this type of format.
ResultSet results = getRecords.executeQuery(); //run database query
Result result = ResultSupport.toResult(results);
request.setAttribute("result", result);
RequestDispatcher rd = request.getRequestDispatcher("/showReport.jsp"); //redirect to this page with query info
rd.forward(request, response);
In the jsp page, I use this format to populate the page.
the row number is the corresponding to the index of the value on how the query is run.
<c:forEach var="row" items="${result.rowsByIndex}">
<form action = "/runthis/servlet?id=${row[0]}" method = "get" >
Employee Name<input type="text" value="<c:out value="${row[2]}"/>" />
Department<select>
<option value="<c:out value="${row[4]}"/>"><c:out value="${row[4]}"/></option></select>
<input type="submit" value="Save">
</form>
</c:forEach>
So for instance, if someone changes the Employee Name, but leaves the Department field alone, or vice versa, how would I go about this?
I think I should be able to kick this form action to a "update servlet", but I would rather not "update" every element in the record if I do not need to.
Also I'm still learning web dev, so if you can think of a better way to prepopulate stuff, via javascript or whatever, I'm willing to try that as well, if it's a possible solution.
Thanks for any help!
i think you need to do something like this:
<c:forEach var="row" items="${result.rowsByIndex}">
<form action="/runthis/servlet" method="post">
<input type="hidden" name="id" value="<c:out value="${row[1]}"/>" />
<input type="hidden" name="EmployeeName_orig" value="<c:out value="${row[2]}"/>" />
Employee Name<input type="text" name="EmployeeName" value="<c:out value="${row[2]}"/>" />
<input type="hidden" name="Department_orig" value="<c:out value="${row[4]}"/>" />
Department
<select id="Department" name="Department">
<option value="<c:out value="${row[4]}"/>"><c:out value="${row[4]}"/></option>
</select>
<input type="submit" value="Save" />
</form>
</c:forEach>
and then, in your update servlet (here called /runthis/servlet) you do some form of update employee and set the name and department where the row is id. note that i send the id in a hidden field, but it could just as well be sent in the url as you mentioned in our discussion above!
about your remark on updating every element in a record:
this can be done in different ways. one way is to load the record from database first, and compare the fields to know what fields to update. but that would require an extra read from the database before the update.
another way (the one i have prepared for in my proposed solution) is to have hidden fields, one for each input in your form. this hidden field holds the original value for its input counterpart. this way you can compare the original value with the new value without having to do a read from the database. on the other hand, you're now transferring the double amount of data over the line for each post request.