Prevent duplicate entry in database Codeigniter - codeigniter

Question

I would like to know how to prevent my upload function to insert duplicate entries into the database by using the uid.
public function upload(){
if(!empty($_FILES['uploaded_file']))
{
$path = FCPATH . "/file_attachments/signature_file/";
$path = $path . basename( $_FILES['uploaded_file']['name']);
$base64 = base64_encode(file_get_contents($_FILES['uploaded_file']['tmp_name']));
if(move_uploaded_file($_FILES['uploaded_file']['tmp_name'], $path))
{
$data = array (
'uid' => $this->user->get_uid(),
'image' => $base64,
'name' => basename( $_FILES['uploaded_file']['name']),
);
$this->load->database('employee');
$this->db->insert('signatures', $data);
// echo "The file ". basename( $_FILES['uploaded_file']['name']).
// " has been uploaded";
$alert = "The file ". basename( $_FILES['uploaded_file']['name']).
" has been uploaded";
redirect(base_url() . "signature_uploader/search/?id=" . $alert);
}
else
{
// echo "There was an error uploading the file, please try again!";
$alert ="There was an error uploading the file, please try again!";
redirect(base_url() . "signature_uploader/search/?id=" . $alert);
}
}
}
Here's my view file. I haven't got the time to edit the unnecessary things in here. The problem is still that if it got duplicate entries the database error still shows up and that is what I'm preventing to do so. Cheers!
<div class="bod">
<div class="insta">
<form enctype="multipart/form-data" style="padding-top: 10px" name="exit_form" method="post" action="<?= base_url() ?>signature_uploader/upload">
<input type="hidden" name="uid" value="<?= $agent->get_uid() ?>" />
<input type="hidden" name="gid" value="<?= $agent->get_gid() ?>" />
<input type="hidden" name="fname" value="<?= $agent->get_fname() ?>" />
<input type="hidden" name="lname" value="<?= $agent->get_lname() ?>" />
<div style="text-align: center; font-size: 25pt; margin-bottom: 15px">Signature Uploader</div>
<table width="105%">
<tr>
<td width="40%"><strong>Name: </strong><input class="textinput" disabled="disabled" type="text" name="full_name" id="textfield3" size="35" value="<?= $agent->get_fullName() ?>" /></td>
<tr/>
<tr>
<td><label>Upload Image File:</label><br /> <input name="uploaded_file" type="file" accept=".png" required/>
</tr>
<table/>
<br />
<input type="submit" value="Submit" class="button1" />
</form>
<br/>
</div>

Answer 1

You can use from Codeigniter form validation to prevent from duplicate entry:
at first you must get the uid in the form view like this:
<input type="hidden" name="uid" value="<?php echo $this->user->get_uid() ?>">
and then in your controller:
public function upload(){
if(!empty($_FILES['uploaded_file']))
{
$this->load->helper(array('form', 'url'));
$this->load->library('form_validation');
$this->form_validation->set_rules('uid', 'UID', 'is_unique[signatures.uid]');
if ($this->form_validation->run() == FALSE)
{
// Your Code if the uid is duplicate
$alert ="Could't upload because of duplicate entry!";
redirect(base_url() . "signature_uploader/search/?id=" . $alert);
}
else
{
// Your Code if the uid is unique
$path = FCPATH . "/file_attachments/signature_file/";
$path = $path . basename( $_FILES['uploaded_file']['name']);
$base64 = base64_encode(file_get_contents($_FILES['uploaded_file']['tmp_name']));
if(move_uploaded_file($_FILES['uploaded_file']['tmp_name'], $path)) {
$data = array (
'uid' => $this->input->post('uid'),
'image' => $base64,
'name' => basename( $_FILES['uploaded_file']['name']),
);
$this->load->database('employee');
$this->db->insert('signatures', $data);
// echo "The file ". basename( $_FILES['uploaded_file']['name']).
// " has been uploaded";
$alert = "The file ". basename( $_FILES['uploaded_file']['name']).
" has been uploaded";
redirect(base_url() . "signature_uploader/search/?id=" . $alert);
} else{
// echo "There was an error uploading the file, please try again!";
$alert ="There was an error uploading the file, please try again!";
redirect(base_url() . "signature_uploader/search/?id=" . $alert);
}
}
}
}

Answer 2

Either you can check weather such file exists or not, but normally while creating a code which uploads file, has a function which will generate unique name for each file that we upload. So in such cases it will have duplicate entries with different name.
Only way i see is to create a function that will check weather the file name already exists in database.