I want to upload an item object with it's image is it possible that i pass a complete object of my Item along with it's image from my Controller if yes then how may i Do it? and I need a Json Pattern also which will be coming from client side.
What would be the Json pattern for my following Item Object.
Class Item{
String ItemID;
String ItemName;
String CategoryID;
List<Image> imagesList;
}
Class Image{
String imageId;
String imageTitle;
byte[] image;
}
and one more thing. Please tell me how can I pass two parameters in my Controller. e.g. if I want to pass Item object in the Request Body along with an extra parameter say String UserID. HOw may I write the following code.
#RequestMapping(method = RequestMethod.POST)
#ResponseStatus(HttpStatus.CREATED)
public void add(#RequestBody Item myItem, String UserID)
{ ...... }
and please tell me what if I pass in the Request in Json format. What will be it looks like?
{ "Item" : { "ItemID": "1", ......}, "UserID" : "hello"}
will it be like this or what? because i tried it i'm getting the Object and string as Null. I also tried it with #RequestParam but same got NULL while debugging.
Currently i'm dealing with this by this.
Class ItemUserPost{
Item item;
String UserID;
}
I'm storing this object in MongoDB. Will be my whole collection of Item will stored along with the images? or i have to use a MultiPart and GridFS API for this. Kindly please refer if related question already posted.
Please Help Urgent.
Thanks in Advance.
The Request Body it's just ONE body. You cannot pass multiple objects or parameters in the same body.
There is 2 turnovers for this:
If you're using REST, you can put the UserID on #RequestMapping(value = "{userId}") and get it from the URL. Or, you can simply put the UserId as query parameter on your url.
Keep using your ItemUserPost object.
--
And for the second question:
Yes, It will store your collection with the images.
Related
eg:
http://host:port/template/products/?productid=1234,1235
how to implement rest api for the above url where in single queryparam passing multiple values and get the all existing records for the productids
Try something like below to accomplish what you are trying to do:
#RequestMapping(value="/products", method=RequestMethod.GET)
public String getMultipleProductsInfo(#RequestParam List<Long> productIdList) {
String productsInfoAsString = getExistingRecordsForTheProductIds(productIdList);
return productsInfoAsString;
}
Notice the
#RequestParam List productIdList
The comma separated list of product IDs are copied into the productIdList list object. You can either iterate through the list or send it over to the method that is responsible for fetching the results from the datasource, such as your database
Please note that the above code snippet returns the response as String. But you could make your API return a response in other formats too, such as JSON.
I have an application where there will be several parameters passed to my endpoint for searching, these parameters are not defined because they are dynamically generated so i cannot map it to a specific model. What would be the best way to map any query parameters into my GET endpoint?
[HttpGet]
public CustomResponse GetResults({something here that will map the parameters?})
{
//perhaps a dictionary? a collection of some sort?
}
Then I need to get all those keys and values and search the database for anything containing that and as i said it could be anything.
So I could pass something like?
/api/Merchandise/GetResults?sku=30021&cupsize=medium&color=red&location=south& {and all the dynamic fields which could be anything}
HttpRequest object has Query property that is an IQueryCollection and holds all passed query parameters.
In other words, in your action method you may do:
[HttpGet]
public CustomResponse GetResults()
{
var queryParams = HttpContext.Request.Query;
// directly get by name
var value1 = queryParams["parameter_name"];
// or queryParams.TryGetValue()
foreach (var parameter in queryParams)
{
string name = parameter.Key;
object value = parameter.Value;
}
}
You could map it to JObject, which is like a Dictionary.
Don't forget:
using Newtonsoft.Json;
I am pretty new in Spring MVC and I have the following doubt about how correctly achieve the following task.
I am working on a web application that implement a user registration process. This registration process is divided into some consecutive steps.
For example in the first step the user have to insert a identification code (it is a code that identify uniquely a user on some statal administration systems) and in the second step it have to compile a form for his personal data (name, surname, birth date, and so on).
So, actually I have the following controller class that handle these steps:
#Controller
public class RegistrazioneController {
#Autowired
private LoadPlacesService loadPlacesService;
#RequestMapping(value = "/iscrizioneStep1")
public String iscrizioneStep1(Model model) {
return "iscrizioneStep1";
}
#RequestMapping(value = "/iscrizioneStep2", method=RequestMethod.POST)
public String iscrizioneStep2(Model model, HttpServletRequest request, #RequestParam("cf") String codicFiscale) {
System.out.println("INTO iscrizioneStep2()");
//String codicFiscale = request.getParameter("cf");
System.out.println("CODICE FISCALE: " + codicFiscale);
model.addAttribute("codicFiscale", codicFiscale);
return "iscrizioneStep2";
}
#RequestMapping(value = "/iscrizioneStep3", method=RequestMethod.POST)
public String iscrizioneStep3(#ModelAttribute("SpringWeb")Step2FormCommand step2Form, ModelMap model, HttpServletRequest request) {
System.out.println("INTO iscrizioneStep3()");
System.out.println("NOME: " + step2FormCommand.getName());
return "iscrizioneStep3";
}
Into the iscrizioneStep2() it is retrieved the first code (#RequestParam("cf") String codicFiscale).
Into the iscrizioneStep3() it is retrieved a command object containing the data inserted into the form of the view in which this form was submitted, this one:
#ModelAttribute("SpringWeb")Step2FormCommand step2FormCommand
It works fine.
Now my problem is that I have another object named Step3View that have to be initialized with the aggregation of the #RequestParam("cf") String codicFiscale object retrieved into the iscrizioneStep2() method and the #ModelAttribute("SpringWeb")Step2FormCommand step2FormCommand retrieved into the iscrizioneStep3() method.
This Step3View class simply contain the String codicFiscale and all the fields of the Step2FormCommand class.
Now my doubts are: what is the best way to handle this situation? Where have I to declare this Step3View object? at controller level? (so I can use it in all my controller methods?). Have I to annotate this class with #Component (or something like this) to inject it in my controller?
What is the best solution for this situation?
I think in order to get an answer you need to understand the question and ask the right question. I think your question is "how do I pass a parameter from one page to another page in SpringMVC?". You specifically want to know how to pass the "cf" param, but readers here will tend to pass over questions that are too specific because it takes too much time to figure out what you want.
In answer to that, see Spring MVC - passing variables from one page to anther as a possible help.
Also, there are many good answers about this question for JSP in general, which can be worked into the SpringMVC architecture. See How to pass value from one jsp to another jsp page? as a possible help.
Say you have a repository method to update a Document:
public Document UpdateDocument(Document document)
{
Document serverDocument = _db.Documents.Find(document.Id);
serverDocument.Title = document.Title;
serverDocument.Content = document.Content;
_db.SaveChanges();
return serverDocument;
}
In this case, the entity has two properties. When updating a Document, both of these properties are required in the JSON request, so a request to PUT /api/folder with a body of
{
"documentId" = "1",
"title" = "Updated Title"
}
would return an error because "content" was not provided. The reason I'm doing this is because, even for nullable properties and properties that the user doesn't update, it seems safer to force the client to specify these fields in the request to avoid overwriting unspecified fields with nulls serverside.
This has led me to the practice of always requiring every updatable property in PUT and POST requests, even if it means specifying null for those properties.
Is this cool, or is there a pattern/practice that I haven't learned about yet that might facilitate partial updates by sending only what is needed over the wire?
The best practice in API design is to use HTTP PATCH for partial updates.
In fact, use cases like yours are the very reason why IETF introduced it in the first place.
RFC 5789 defines it very precisely:
PATCH is used to apply partial modifications to a resource.
A new method is necessary to improve interoperability and prevent
errors. The PUT method is already defined to overwrite a resource
with a complete new body, and cannot be reused to do partial changes.
Otherwise, proxies and caches, and even clients and servers, may get
confused as to the result of the operation. POST is already used but
without broad interoperability (for one, there is no standard way to
discover patch format support).
Mark Nottingham has written a great article about the use of PATCH in API design - http://www.mnot.net/blog/2012/09/05/patch
In your case, that would be:
[AcceptVerbs("PATCH")]
public Document PatchDocument(Document document)
{
Document serverDocument = _db.Documents.Find(document.Id);
serverDocument.Title = document.Title;
serverDocument.Content = document.Content;
_db.SaveChanges();
return serverDocument;
}
Is this cool, or is there a pattern/practice that I haven't learned
about yet that might facilitate partial updates by sending only what
is needed over the wire?
A good practice of doing a POST or PUT is to only include values that you need for that specific request. In doing the UpdateDocument you should ask yourself what "really should be done here"? If you have a hundred fields on that object do you need to update all of them or only part of them. What "action" are you really trying to do?
Let's have an illustration for those questions, say we have a User object that has the following fields:
public class User {
public int Id {get;set;}
public string Username {get;set;}
public string RealName {get;set;}
public string Password {get;set;}
public string Bio {get;set;}
}
You then have two use cases:
Update the profile of a User
Update the password of a User
When you do each of those you will not, or it's a good idea to, have one update method that will do both. Instead of having a generic UpdateUser method you should have the following methods:
UpdateProfile
UpdatePassword
Methods that accepts fields that they just need, nothing more, nothing less.
public User UpdateProfile(int id, string username, string realname, string bio) {
}
public User UpdatePassword(int id, string password) {
}
Now comes the question:
I have a use case that a "user action" allows for an update on
multiple fields where some of the fields can have "no input" from the
user but I don't want to update that field in my model.
Suppose a user updates his/her profile and provided values for Username, RealName but not for Bio. But you do not want to set Bio as null or empty if it has a value already. Then that becomes a part of your application's business logic and that should be handled explicitly.
public User UpdateProfile(int id, string username, string realname, string bio) {
var user = db.Users.Find(id);
// perhaps a validation here (e.g. if user is not null)
user.Username = username;
user.RealName = realname;
if (!string.IsNullOrEmptyWHiteSpace(bio)) {
user.Bio = bio;
}
}
Spring documentation says:
Use the #RequestParam annotation to bind request parameters to a
method parameter in your controller.
AFAIK, request parameters are variables retrieved from query strings if the request method is GET. They are also the variables retrieved from the form values when the request method is POST. I've verified this using a simple JSP that displays request parameters through method request.getParameter("key").
But it seems to me that #RequestParam only works on GET method requests. It can only get values from query strings.
Is this a bug in the documentation? Can someone please cite me some documentation that describes exactly what #RequestParam is used for, what it cannot be used for, and how it gets populated?
Can I use #RequestParam for POST methods to get the form values? If I can't use #RequestParam, what else can I use? I'm trying to avoid calling request.getParameter("key").
It works with posts too. Can you post your method body and you html?
Yes it works perfectly with post method too. you can mention the method attribute of #RequestParam as RequestMethod=POST. Here is the code snippet
#RequestMapping(value="/register",method = RequestMethod.POST)
public void doRegister
(
#RequestParam("fname") String firstName,
#RequestParam("lname")String lastName,
#RequestParam("email")String email,
#RequestParam("password")String password
)
Instead of #RequestParam which binds to a single form value, you can use #ModelAttribute annotation and bind to the whole object. But it should be used in conjunction with form or bind Spring's JSTL.
Example:
- controller that calls JSP-page, it should add objects to a Model:
#RequestMapping(value="/uploadForm", method=RequestMethod.GET)
public String showUploadForm(Model model) {
Artist artist = new Artist();
Track track = new Track();
model.addAttribute("artist", artist);
model.addAttribute("track", track);
return "uploadForm";
}
JSP might look something like that:
Track Title *:
Controller that processes form submission;
#RequestMapping(value="/uploadToServer", method=RequestMethod.POST)
public String uploadToServer(#ModelAttribute("artist") Artist artist, #ModelAttribute("track") Track track) { .... }
Here I found a good explanation of using #ModelAttribute annotation - krams915.blogspot.ca