Uploading a file with JavaScript/Ajax to SpringBoot endpoint

I am new to front-end development and am having troubles piecing together a solution for this specific form setup.

I have an already created jsp representing this instance creation page. It’s a form containing numerous drop downs and check boxes. I need to add a file upload option to it.

The jsp is set up like this…

<form class="form-horizontal" id="editInstanceForm" onsubmit="return false;"> ....

Here’s my input field

<div class="form-group" id="uploadForm">
    <label class="col-xs-4 control-label instanceDefaultLabel" for="fileSearchField">Default Location and Zoom:</label>
    <div class="col-xs-3">
        <input name="myFile" type="file" id="fileSearchField" multiple=false>
        <button id="upload-button">Upload</button>
    </div>
    .....
</div>

Now I have an ajax call that I was originally wanting to use before I realized that the whole form is attempting to submit when I uploaded the file. Here it is…

$('#upload-button').click( 'click',
    function() {
        var form = $('#fileSearchField')[0];
        var data = new FormData(form);

        $.ajax({
            type: "POST",
            enctype: 'multipart/form-data',
            url: "/edit/uploadfile",
            data: data,
            processData: false, 
            contentType: false,
            cache: false,
            success: function (data) {
                alert("hi stuff worked");
            },
            error: function (e) {
                alert("nope!");
            }
        });
    }
);

I got this suggestion in researching how to upload a file with jQuery/ajax and Spring Boot (I am using Spring Boot to create my endpoint). Here are some articles that I have been reading in an attempt to understand how to do this…

https://www.mkyong.com/spring-boot/spring-boot-file-upload-example-ajax-and-rest/

http://javasampleapproach.com/spring-framework/spring-boot/multipartfile-create-spring-ajax-multipartfile-application-downloadupload-files-springboot-jquery-ajax-bootstrap#3_Implement_upload_controller

and many more. This seemed like the solution until I realized this was a form and I think I need to save all the fields at once. This is going to mean that I have to modify the already created ajax function that saves this form and passes it to the end point. Now I don’t know how to get my MulitpartFile in as part of this different function. The existing one is like this…

 $.ajax({
    type: "POST",
    url: webroot + "/viewerConfig/mapInstance/insertOrUpdate",
    data: JSON.stringify(instanceData),
    processData: false,
    contentType: 'application/json',
    success: function (data) {
        if (data.status === "OK") {
            alert("Instance created/updated successfully");
        } else {
            alert("Unknown error");
        }
    },
    fail: function () {
        alert("Unknown error");
    },
    error: function (a) {
        alert("Unknown error");
    }
});
});

This is exactly where I am stuck and I need to be pointed in the correct and productive direction.

I don’t know if this will help but here’s my end point that looks like the one I have to hit with my file param added…

@RequestMapping(value = "/insertOrUpdate", method = RequestMethod.POST, consumes = "application/json")
public @ResponseBody BaseStatusResponse insertOrUpdate(final @RequestBody SaveAdminInstanceView newInstance, HttpServletResponse servletResponse,
                                                       @RequestParam MultipartFile file)

EDIT: I have done some curl troubleshooting and it’s the MulitpartFile that’s failing. I am passing it as suggested yet I am getting this exception:

org.springframework.web.multipart.MultipartException: The current request is not a multipart request</p><p><b>Description</b> The server encountered an unexpected condition that prevented it from fulfilling the request.</p><p><b>Exception</b></p><pre>org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.web.multipart.MultipartException: The current request is not a multipart request

Answer

You can try below code:

$.ajax({
  url: "/edit/uploadfile",
  type: 'POST',
  data: new FormData($(this)[0]),
  enctype: 'multipart/form-data',
  processData: false, // tell jQuery not to process the data
  contentType: false, // tell jQuery not to set contentType
  cache: false,

  success: function(res) {
    console.log(res);
  },

  error: function(res) {
    console.log('ERR: ' + res);
  }
});

And in controller, you needn’t declare consumes = "application/json"

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Answer