I am new to spring and JSP. My web application is spring powered, which I run locally in apache tomcat.
In my JSP page I have multiple file-upload inputs and many text input fields.
Every time, when I press any of the upload buttons, a HTTP POST request goes to my controller from where on I may save the image to the database.
But, what I want is:
I will upload the images one by one ( preferably by staying in the page) but won't save them in database and then when I press submit to get the rest of the input text fields data, I commit all the data, including image, texts to the database in one try.
I have heard of scope="session" for my controller(bean) in the dispatcher-servlet.xml ... but I am unsure as to if I upload image to my controller and get back to my JSP form, will the bean keep my already uploaded images?
I think it is hard for me to explain, so please let me know if my question is not clear.
It would be nice if anybody can come up with a suggestion that may help to obtain my goal.
Are you uploading a varying number of images, as in if someone wants to upload only 2 they'll have 2 file fields on the form, or does everyone get 5 fields for example?
To be honest, the whole scheme of incremental upload sounds a bit overcomplicated at this stage. (Unless you have an explicit need to show progress bars on each upload, etc.) What if the user abandons the form after uploading the first image? You'd need a pretty solid mechanism to keep track of the entire visit, keeping it in the session wouldn't help here. Can a user pick up where they left off? If you make the whole thing work with single form submit click first, you can break it out and fine tune the process later. I mention that since you stated you're new to jsp and Spring (what's your experience with web dev otherwise?)
I think the best way is to upload file using ajax control rather than submitting form for each upload and store the file references in session scope variable(attribute). there are lot of libraries have ajax based file uploading like extJS, JQuery, GWT, DWR , whatever ajax library you are using in your web application.
Related
I am in the process of creating a simple application with Spring Mvc and thymeleaf and I am currently thinking of what functionality I want to implement but I don't know exactly how to do it.
Let's say I have a model class Person. Regularly I have a form and a controller where I am passing the new person object and persist it with JPA.
No problem there but what if I want to have a page that I give some of the person basics info and then hit the "next" button and give some additional information. Then hit "next" again, review the data and hit "save"?
You can do it by integrate Spring Webflow in your project.
Webflow is basically extensive part of WebMvc. Webflow has some configuration that, where you have to start and where you should go. If you have 5 page and you would like to all these data will put into database in one process then Webflow will help you. One more advantage is, you can add validation in particular pages and particular means you have five model and all these model will work in one flow.
Read more, https://projects.spring.io/spring-webflow/
I have not used Thymeleaf, but usually this kind of problem can be solved using some of the following methods or something similar:
1.) Save the unfinished data to database using the same schema or some other schema for this (or in session; in general sense, save it somewhere on server side). Problem with this is how to get rid of abandoned data where user has not moved to finish.
2.) Drag the data from page to page with request parameters. If the requests are of type POST then just in POST body, if they are type GET then as query parameters. Problem with this is it's not very clean.
3.) Don't do full page requests. Solve it with some front end solution using Javascript. Depending on the app it might or might not be possible.
4.) Do full page requests but still solve it in front end using local storage or session storage. Similar problems as with keeping the data in server side session.
I'm not entirely sure I am asking the question correctly but here goes.
I am trying to view customer data via the REST service. I've gotten the login and and can view the servlet(Response as HTML), atleast i thought it was the servlet, i just realized its just the path to the servlet/start.
I think what I am seeing is just the hardcoded HTML messages that get viewed depending on customer data. Viewing as JSON doesn't work either i get "The content you are trying to view cannot be viewed as JSON"
I'm sorry I don't know enough to ask this properly
Well, it was a n00b mistake. I didnt call the action prior to loading the page so there was no data to ever load.
I'm trying to learn some basic knowledge of jsp, suppose that I have a project, in this project, after signing in, I have a Main.jsp with a calendar or a dropdown list in it, when selecting a date, I'll change the UI based on the data from database.
I can put all relevant data into request after signing in, and use JSTL in Main.jsp, but if the data is huge, this doesn't sound like a good idea, right?
Back to the old age when there's no JSTL or AJAX, how does jsp developer deal with this? And what is the best practice nowadays?
Thanks.
If you are talking to render about without JSTL or AJAX, the only option i see is to submit/send the form to server and get it back with updated view, but yes it will cost a lot in terms of performance.
I think for your use case:
1) you can get the data from server via AJAX on every update,
2) or, if the data is not customer dependent and is fixed in terms of UI, you can load it lazily in background, and change the view immediately on the user action.
I have a Ext.grid.Panel and I fill it with store that is populated from database. And there is an export button. When the user click on the Export button, I want the data from grid should start downloading like .csv file
The best solution to creating any type of file (Excel, CSV, PDF, whatever) is going to be leveraging your application server to create and serve up the file for download. There are literally thousands of libraries across most of the popular server-side languages that can create just about any kind of file that you'd want to create.
So ultimately this has nothing to do with Ext JS or even JavaScript. All that your export button should do, IMO, is to create an AJAX request which triggers the process (query, transform results, publish to a correct content type, stream to browser) that will be needed to generate the content from your application server technology.
Sometimes you can't leverage an application server such as when your back end is a micro controller or you can't get the back end people to make the change.
I've not used this, but it looks nice:
http://www.sencha.com/forum/showthread.php?136598-Export-store-to-Excel
We are developing a web application with ExtJs 4 and Microsoft RIA services + MS SQL Server on the back end. Currently some of the records we store in the DB have attached images to them. Images are stored in binary format in the DB.
What would be the best approach to:
Display them within ExtJs framework
Allow users to upload images via same ExtJs front end
I looked through ExtJs docs and looks like we would need to provide images as basically individual files and use simple img tag for that. Is that correct assumption? Are there other approaches to render images from binary data (which we currently serve via JSON endpoints)?
Is there samples handy for image upload logic?
ExtJS will give you a framework for getting the images via forms to your back end, but what you do with the images from there is completely ExtJS independent. Displaying them within ExtJS is completely independent of the back end logic as well. It's just a matter of finding a way to pipe the data up to the browser just as you would if you were writing a normal HTML page.
I'll take the answer one step further and mention: Storing images in the database is generally a bad idea. At least, storing them in a relational database is generally not a great plan. If I couldn't use a database like Riak (or Amazon's S3) for storing the images, I would probably follow Diodeus' comment and put them directly in the filesystem.