I have a form with text inputs and file inputs; the text fields are being validated. Is there a way to have the form remember which files the user has already selected if they hit submit but need to go back because one of the text fields didn't validate?
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问题:
回答1:
You can't "pre-fill" the contents of a file upload field for security reasons. Also, that would mean the file would get re-uploaded every time the form is submitted, which would not be good.
Instead, do this:
- Create a file upload field with name
file_upload. - On the server-side, process the upload in any case, even if the rest of the form validation fails.
- If the form validation failed, but the file was uploaded, insert a hidden input into the form with name
filecontaining the name of the just uploaded file. - Display a user-visible indication that the file is okay. If it's an image, display a thumbnail version of it. If it's any other file, display its filename and/or icon.
- If the user chooses to upload a different file in the
file_uploadfield, process the upload and store the new value infile.
Pseudocode:
<?php $file = null; if (!empty($_POST['file'])) { $file = $_POST['file']; } if (!empty($_FILES['file_upload'])) { // process upload, save file somewhere $file = $nameOfSavedFile; } // validate form ?> <input type="file" name="file_upload" /> <input type="hidden" name="file" value="<?php echo $file; ?>" /> <?php if (!empty($file)) { echo "File: $file"; } ?> Important note
This mechanism can allow any user to claim other user's files as their own, by including a file name that they guessed exists on your server. You will want to ensure that uploaded files are clearly associated with a specific user to avoid this issue.
回答2:
files input fields are read-only you can't set an initial value for them
回答3:
You can upload the Files anyway and display the filenames instead of the file select box. To remember the fields, you can use a $_SESSION variable.