{"id":4512,"date":"2011-11-18T19:17:50","date_gmt":"2011-11-18T13:47:50","guid":{"rendered":"http:\/\/www.tothenew.com\/blog\/?p=4512"},"modified":"2017-03-20T17:05:11","modified_gmt":"2017-03-20T11:35:11","slug":"uploading-multiple-files-with-same-name","status":"publish","type":"post","link":"https:\/\/www.tothenew.com\/blog\/uploading-multiple-files-with-same-name\/","title":{"rendered":"uploading multiple files with same name"},"content":{"rendered":"

A good binding feature in grails is that when you have multiple input fields with same name, they are available as a list in params<\/code>. But this does not hold with html file input fileds. If you have multiple file input fields with same name, params.fieldName<\/code> will not return a list but the first input field with name fieldName<\/code>. This is due to using fileMap<\/code> attribute of request<\/code> object. Here is the relevant part of GrailsParameterMap<\/code> class(I suspected this class because of params.getClass()<\/code> returned GrailsParameterMap<\/code>) : <\/p>\n

[groovy]
\n GrailsParameterMap(HttpServletRequest request) {
\n\t\/\/………………………..
\n if (request instanceof MultipartHttpServletRequest) {
\n def fileMap = request.fileMap
\n for (fileName in fileMap.keySet()) {
\n requestMap.put(fileName, request.getFile(fileName))
\n }
\n }
\n\t\/\/………………………..
\n }
\n[\/groovy]
\nDue to above implementation, If you have three file input fields with name familyPics<\/code>, only the first one will be available via params.familyPics<\/code> of type CommonsMultipartFile<\/code>. <\/p>\n

\nIn one of the mail thread(links at the end of the blog), I got to know that grails uses Spring 3.0<\/em> starting from grails version 1.2<\/em> which supports multiFileMap<\/code> attribute in request<\/code> object. Using this attribute you can access multiple files from inputs with the same name (or that uses the HTML5<\/em> multiple attribute). So if the implementation is changed to something like :
\n[groovy]
\n GrailsParameterMap(HttpServletRequest request) {
\n\t\/\/………………………..
\n if (request instanceof MultipartHttpServletRequest) {
\n def multipleFileMap = request.multiFileMap
\n\/* instead of using fileMap. However this map value is always a list even if there is only one file input for a name *\/
\n multipleFileMap.each {fieldName, files -&amp;gt;
\n if (files.size() == 1) {
\n requestMap.put(fieldName, files.first())
\n\/* Make this available as a single element instead of list, if the user wants he can use params.list(‘fieldName’) for list version *\/
\n } else {
\n requestMap.put(fieldName, files)
\n }
\n }
\n }
\n\t\/\/………………………..
\n }
\n[\/groovy]
\nThen if there are three file input fields with name familyPics<\/code>, then params.familyPics<\/code> will return a list of CommonsMultipartFile<\/code> objects. If there is only one file input field with name profilePic<\/code> then params.profilePic<\/code> will return an object of type CommonsMultipartFile<\/code> and params.list('profilePic')<\/code> will return a list of CommonsMultipartFile<\/code> objects.<\/p>\n

\n

This feature can be added using Groovy\/Grails MetaProgramming<\/em>(Until grails is updated for this feature). However I went with Grails Filter<\/em> solution. Create\/update a filter with this entry :\n<\/p>\n

[groovy]
\n multipartFileSupport(controller: ‘*’, action: ‘*’) {
\n before = {
\n if (request instanceof MultipartHttpServletRequest) {
\n def multipleFileMap = request.multiFileMap
\n multipleFileMap.each {fieldName, files -&amp;gt;
\n if (files.size() == 1) {
\n params.put(fieldName, files.first())
\n } else {
\n params.put(fieldName, files)
\n }
\n }
\n }
\n }
\n }
\n[\/groovy]<\/p>\n

Now inside any controller\/action you can access statements like(even grails auto binding will work fine) :
\n[groovy]
\n\/* Suppose there is a file input field with name profilePic *\/
\nCommonsMultipartFile profilePic=params.profilePic
\nList&amp;lt;CommonsMultipartFile&amp;gt; profilePicAsList=params.list(‘profilePic’)<\/p>\n

\/* Suppose there are three file input fields with same name familyPics *\/
\nList&amp;lt;CommonsMultipartFile&amp;gt; familyPics=params.familyPics
\n[\/groovy]<\/p>\n

Hope this feature will be available soon in grails without having to write filters or doing meta programming.<\/p>\n

\n

Helpful links : <\/p>\n

http:\/\/stackoverflow.com\/questions\/3710232\/how-to-iterate-over-uploaded-files-in-grails<\/a><\/p>\n

http:\/\/forum.springsource.org\/showthread.php?44632-CommonsMultipartResolver-Uploading-many-files-with-same-html-name<\/a>\n<\/p>\n

\n

~~~~~~Cheers~~~~~~~
\nBhagwat Kumar
\nbhagwat(at)intellligrape(dot)com<\/p>\n","protected":false},"excerpt":{"rendered":"

Grails does not support accessing multiple file input fields with same name using params.fieldName. We need to use request.multiFileMap (available in Spring 3.0) instead of request.fileMap. The blog provides sample code to achieve this feature via Grails Filter.<\/p>\n","protected":false},"author":13,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"iawp_total_views":14,"footnotes":""},"categories":[7],"tags":[684,686,636,685,687,688],"class_list":["post-4512","post","type-post","status-publish","format-standard","hentry","category-grails","tag-commonsmultipartfile","tag-filemap","tag-grails-filters","tag-grailsparametermap","tag-multifilemap","tag-multiple-html-file-input"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t