Pracuję nad tym kodem dla frontu aplikacji ERP.
Pamiętaj, że dopiero po załadowaniu możliwe będzie wstawienie wiadomości.
Będziesz musiał kliknąć edytuj, aby otworzyć modal i wprowadzić treść.

Może jest to przydatne dla Ciebie!

Wstaw do swojego functions.php

<?php
if(!is_admin()){

    if(!function_exists('ajax_upload_files')):
        function ajax_upload_files(){
            wp_enqueue_script('ajax-upload-files', get_template_directory_uri().'js/upload-files.js',array('jquery','plupload-handlers'), wp_get_theme()->get( 'Version' ), true);

            wp_localize_script('ajax-upload-files', 'ajax_vars_files',
                array(
                    'ajaxurl' => admin_url('admin-ajax.php'),
                    'nonce' => wp_create_nonce('o_files'),
                    'theme_url' => get_template_directory_uri(),
                    'number' => 1,
                    'upload_enabled' => true,
                    'plupload' => array(
                        'runtimes' => 'html5,flash,html4',
                        'browse_button' => 'aaiu-uploader',
                        'container' => 'aaiu-upload-container',
                        'file_data_name' => 'aaiu_upload_file_files',
                        'max_file_size' => get_option('max_files'),
                        'max_files' => get_option('max_file_size'),
                        'url' => admin_url('admin-ajax.php') . '?action=o_upload_files&post_ID='.get_the_ID(),
                        'flash_swf_url' => includes_url('js/plupload/plupload.flash.swf'),
                        'filters' => array(
                            array(
                                'title' => 'Accepted files', 
                                'extensions' => "jpg,jpeg,png,gif"
                            )//,bmp,ico,tiff,mp3,mp4,mov,avi,wmv,wav,midi,mid,zip,rar...
                        ),
                        'multipart' => true,
                        'urlstream_upload' => true,
                        'prevent_duplicates' => true,
                    )
                )
            );
        }
        add_action( 'wp_enqueue_scripts', 'ajax_upload_files', 100 );
    endif;

    if( !function_exists('O_upload_files') ): 
        function O_upload_files() {
            $file = array(
                'name' => sanitize_text_field($_FILES['aaiu_upload_file_files']['name']),
                'type' => sanitize_text_field($_FILES['aaiu_upload_file_files']['type']),
                'tmp_name' => sanitize_text_field($_FILES['aaiu_upload_file_files']['tmp_name']),
                'error' => sanitize_text_field($_FILES['aaiu_upload_file_files']['error']),
                'size' => sanitize_text_field($_FILES['aaiu_upload_file_files']['size']),
            );
            $file = O_fileupload_process_files($file);
        }
    endif;
    add_action('wp_ajax_o_upload_files', 'O_upload_files');
    add_action('wp_ajax_nopriv_o_upload_files', 'O_upload_files');

    if( !function_exists('O_handle_file_files') ): 
        function O_handle_file_files($upload_data) {

            $return = false;
            $uploaded_file = wp_handle_upload($upload_data, array('test_form' => false));

            if (isset($uploaded_file['file'])) {
                $parent_post_id = intval($_REQUEST['post_ID']);
                $file_loc = $uploaded_file['file'];
                $file_name = basename($upload_data['name']);
                $file_type = wp_check_filetype($file_name);

                $attachment = array(
                    'post_mime_type' => $file_type['type'],
                    'post_title' => preg_replace('/\.[^.]+$/', '', basename($file_name)),
                    'post_content' => '',
                    'post_status' => 'inherit'
                );

                $attach_id = wp_insert_attachment($attachment, $file_loc, $parent_post_id);
                $attach_data = wp_generate_attachment_metadata($attach_id, $file_loc);

                wp_update_attachment_metadata($attach_id, $attach_data);

                $return = array('data' => $attach_data, 'id' => $attach_id, 'parent_post_ID' => $parent_post_id);

                return $return;
            }

            return $return;
        }
    endif;

    if( !function_exists('O_fileupload_process_files') ): 
        function O_fileupload_process_files($file) {

            $attachment = O_handle_file_files($file);

            if (is_array($attachment)) {
                $html = O_get_html_files($attachment);

                //update_post_meta($attachment['id'],'_set_type_files',$attachment['parent_post_ID']);

                echo json_encode(array('success' => true,'html' => $html,'attach' => $attachment['id']));
                exit;
            }

            echo json_encode(array('success' => false));
            exit;
        }
    endif;

    if( !function_exists('O_get_html_files') ): 
        function O_get_html_files($attachment) {
            $attach_id  = $attachment['id'];
            $post = get_post($attach_id);
            $dir = wp_upload_dir();
            $path = $dir['baseurl'];
            $file = $attachment['data']['file'];
            $html="";
            $html .= $path." 

            return $html;
        }
    endif;


    if( !function_exists('O_update_attachment') ): 
        function O_update_attachment() {
            check_ajax_referer('o_files', 'security');

            global $wpdb;

            $post = get_post($_REQUEST['attachment_ID']);

            $return = $wpdb->update( 
                $wpdb->posts, 
                array(
                    'post_title' => stripslashes($_POST['file_new_title']),
                    'post_content' => stripslashes($_POST['file_new_content']),
                    'post_modified' => date("Y-m-d H:i:s"),
                    'post_modified_gmt' => gmdate("Y-m-d H:i:s")
                ), 
                array( 'ID' => $post->ID ) 
            );

            if(is_wp_error($return)) {
                echo json_encode(array('save'=>false, 'message'=>$return->get_error_message()));
                exit();
            }

            echo json_encode(array('save'=>true, 'message'=>'Done'));

        }
        add_action( 'wp_ajax_o_update_attachment', 'O_update_attachment' );
    endif;


    if( !function_exists('O_remove_attachment') ): 
        function O_remove_attachment() {
            check_ajax_referer('o_files', 'security');

            $post = get_post($_REQUEST['attachment_ID']);

            $return = wp_delete_attachment($post->ID);

            if(is_wp_error($return)) {
                echo json_encode(array('save'=>false, 'message'=>$return->get_error_message()));
                exit();
            }

            echo json_encode(array('save'=>true, 'message'=>'Done'));

        }
        add_action( 'wp_ajax_o_remove_attachment', 'O_remove_attachment' );
    endif;

}//!is_admin
?>

Zapisz następujący kod w folderze js/ swojego szablonu: „upload-files.js”

(function($) {
    "use strict";

    var ajaxURL = ajax_vars_files.ajaxurl;

    //var max = ajax_vars_files.plupload.max_files;
    var max = 1;

    var newFile="";

    if (typeof(plupload) !== 'undefined') {
        var uploader_files = new plupload.Uploader(ajax_vars_files.plupload);
        uploader_files.init();
        uploader_files.bind('FilesAdded', function(up, files) {
            var filesNo = 0;
            $.each(files, function(i, file) {
                if(filesNo < max) {
                    $('#aaiu-upload-files').append(
                        '<div id="' + file.id + '" class="push-5 sending-upload"><i class="fa fa-circle-o-notch fa-spin text-default"></i> ' +
                        file.name + ' (' + plupload.formatSize(file.size) + ') <div></div>' +
                        '</div>');
                }
                filesNo = filesNo + 1;
            });

            up.refresh();
            uploader_files.start();
        });

        uploader_files.bind('UploadProgress', function(up, file) {
            $('#' + file.id + " div").html('<div class="progress progress-sm progress-striped active"><div class="progress-bar progress-bar-success" role="progressbar" aria-valuenow="'+ file.percent +'" aria-valuemin="0" aria-valuemax="100" style="width: ' + file.percent + '%" data-toggle="tooltip" title="'+ file.percent +'">[ '+ (file.percent-2) +'% ] ...</span></div><hr>');
        });

        // On error occur
        uploader_files.bind('Error', function(up, err) {
            $('#aaiu-upload-files').append("<div>Error: " + err.code +
                ", Message: " + err.message +
                (err.file ? ", File: " + err.file.name : "") +
                "</div>"
            );
            swal('ERRO', err.file.name, 'error');
            up.refresh();
        });

        uploader_files.bind('FileUploaded', function(up, file, response) {
            var result_files = $.parseJSON(response.response);
            $('#' + file.id).remove();
            if (result_files.success) {
                if($('#imagelist .uploaded_images').length < max) {
                    newFile += '~~~' + result_files.attach;
                    $('#new_file').val(newFile);
                    $('#imagelist').append('<div class="uploaded_images push-10 label label-success" data-imageid="' + result_files.attach + '"><i class="fa fa-check"></i> ' + file.name + '</div>');

                    if($('#imagelist .uploaded_images').length >= max) {
                        $('#aaiu-uploader').hide();
                    }

                    $('#reload-gallery').trigger('click');

                } else {
                   alert('Exceeded limit');
                }
            }else{
                alert('An error has occurred');
            }
        });

        $('#aaiu-uploader').click(function(e) {
            uploader_files.start();
            e.preventDefault();
        });
    }

    //trigger
    $(document).on("click","#reload-gallery", function(){
        var post_ID = $(this).val();
        $.ajax({
            type: 'GET',
            data:{
                action: 'load'
            },
            cache: false,
            url: ajax_vars_files.theme_url+'attachments.php?post_ID='+post_ID,
            success: function(response){
                $('#load-gallery').html(response);
            },
            error: function(response){
                $('#load-gallery').html('<strong>ERROR:</strong> '+console.log(response));
            }
        });
    });

    $(document).on("click",".btn-modal", function(){
        var attachment_ID = $(this).attr('data-attachment-id');
        $.ajax({
            type: 'GET',
            data:{
                action: 'load',
            },
            cache: false,
            url: ajax_vars_files.theme_url+'attachment-modal.php?attachment_ID='+attachment_ID',
            success: function(response){
                $('#load-request').html(response);
                $('#modal-files').modal('show');
            },
            error: function(response){
                $('#error-files').html('<div class="alert alert-danger alert-dismissable"><button type="button" class="close" data-dismiss="alert" aria-hidden="true">×</button><h3 class="font-w300 push-15">ERROR</h3>'+console.log(response)+'</div>');
            }
        });
    });

    $(document).on("click","#save-file-metadata", function(){
        var data = {
            'action' : 'o_update_attachment',
            'security' : ajax_vars_files.nonce
        };
        $.ajax({
            type: 'POST',
            cache: false,
            url: ajaxURL,
            data: $('form#form-edit-file').serialize()+ '&' + $.param(data),
            success: function(response){
                if(response.save===true){
                    $('#modal-files').modal('hide');
                    setTimeout(function() {
                        alert('Done');
                        $('#reload-gallery').trigger('click');
                    }, 1000);
                }else{
                    $('#error-files').html('<div class="alert alert-danger alert-dismissable"><button type="button" class="close" data-dismiss="alert" aria-hidden="true">×</button><h3 class="font-w300 push-15">ERROR:</h3> '+response.message+'</div>');
                }
            },
            error: function(response){
                $('#error-files').html('<div class="alert alert-danger alert-dismissable"><button type="button" class="close" data-dismiss="alert" aria-hidden="true">×</button><h3 class="font-w300 push-15">ERROR:</h3> '+console.log(response)+'</div>');
            }
        });
    });

    $(document).on("click","#remove-file", function(){
        var data = {
            'action' : 'o_remove_attachment',
            'security' : ajax_vars_files.nonce
        };
        $.ajax({
            type: 'POST',
            cache: false,
            url: ajaxURL,
            data: $('form#form-edit-file').serialize()+ '&' + $.param(data),
            success: function(response){
                if(response.save===true){
                    $('#modal-files').modal('hide');
                    setTimeout(function() {
                        alert('Done');
                        $('#reload-gallery').trigger('click');
                    }, 1000);
                }else{
                    $('#error-files').html('<div class="alert alert-danger alert-dismissable"><button type="button" class="close" data-dismiss="alert" aria-hidden="true">×</button><h3 class="font-w300 push-15">ERROR:</h3> '+response.message+'</div>');
                }
            },
            error: function(response){
                $('#error-files').html('<div class="alert alert-danger alert-dismissable"><button type="button" class="close" data-dismiss="alert" aria-hidden="true">×</button><h3 class="font-w300 push-15">ERROR:</h3> '+console.log(response)+'</div>');
            }
        });
    });



})(jQuery);

Zapisz następujący kod w katalogu głównym szablonu: „attachments.php”

<?php
if(isset($_GET['post_ID'])){
    $parse_uri = explode('wp-content', $_SERVER['SCRIPT_FILENAME']);
    require_once($parse_uri[0] . 'wp-load.php');
    $post_ID = $_GET['post_ID'];
}else{
    global $post;
    $post_ID = $post->ID;
}
$file_attachments = get_posts( array(
    'post_type' => 'attachment',
    'nopaging' => true,
    'cache_results' => true,
    'post_parent' => $post_ID,
    'order' => 'ASC',
) );
foreach ( array_reverse($file_attachments) as $attachment ):
    $file_name_link = wp_get_attachment_link( $attachment->ID, false );
    $file_title = apply_filters( 'the_title', $attachment->post_title); 
    $file_content = $attachment->post_content;
    $attachment_url = wp_get_attachment_url($attachment->ID);
    $image = wp_get_attachment_image_src($attachment->ID, 'medium', true )[0];

    echo '<div class="col-md-3 attachments-grid">';
        echo '<img src="'.$image.'" width="100%">';
        echo $file_title.'<br>';
        echo $file_content.'<br>';
        echo '<a href="'.$attachment_url.'" target="_blank">Download</a>';
        echo '<a class="btn-modal" data-attachment-id="'.$attachment->ID.'">Edit</a>';
    echo '</div>';
endforeach;

wp_reset_postdata();
wp_reset_query();

Zapisz następujący kod w katalogu głównym szablonu: „attachment-modal.php”

<?php
if(isset($_REQUEST['attachment_ID'])){
    $parse_uri = explode('wp-content', $_SERVER['SCRIPT_FILENAME']);
    require_once($parse_uri[0] . 'wp-load.php');
    $post = get_post($_REQUEST['attachment_ID']);
    ?>
    <div class="modal fade" id="modal-files" tabindex="-1" role="dialog" aria-hidden="true">
        <div class="modal-dialog modal-dialog-popout">
            <div class="modal-content">
                <div class="block block-themed block-transparent remove-margin-b">
                    <div class="block-header bg-primary-dark">
                        <ul class="block-options">
                            <li>
                                <button data-dismiss="modal" type="button"><i class="fa fa-close"></i></button>
                            </li>
                        </ul>
                        <h3 class="block-title">FILE: "<?php echo $post->post_title;?>"</h3>
                    </div>
                    <div class="block-content row">
                        <span id="error-files"></span>

                        <div class="col-lg-8">
                            <form id="form-edit-file" name="form-edit-file">
                                <div class="form-group">
                                    <div class="form-material">
                                        <input class="form-control" value="<?php echo $post->post_title;?>" name="file_new_title" type="text">
                                        <label for="material-text">Title</label>
                                    </div>
                                </div>

                                <div class="form-group">
                                    <div class="form-material">
                                        <textarea class="form-control" name="file_new_content" rows="3"><?php echo $post->post_content;?></textarea>
                                        <label for="material-textarea-small">Description</label>
                                    </div>
                                </div>

                                <input value="<?php echo $post->ID;?>" name="attachment_ID" type="hidden">

                            </form>
                        </div>
                        <div class="col-lg-4">
                            <?php
                            $type = get_post_mime_type($post->ID);
                            switch ($type) {
                                case 'image/jpeg':
                                case 'image/jpg':
                                case 'image/png':
                                case 'image/gif':
                                case 'application/jpg':
                                    $file = wp_get_attachment_image( $post->ID, array('700', '600'), "", array( "class" => "img-responsive" )  ); 
                                break;
                            }   
                            echo $file;
                            ?>      
                        </div>

                    </div>

                </div>
                <div class="modal-footer">
                    <button id="remove-file" class="btn btn-sm btn-danger pull-left" type="button"><i class="fa fa-trash"></i> Remove</button>
                    <button id="save-file-metadata" class="btn btn-sm btn-success" type="button"><i class="fa fa-save"></i> Save</button>
                </div>
            </div>
        </div>
    </div>
    <?php
}
?>

To na pierwszej stronie, na jednej stronie

<div class="submit_container">
    <div id="upload-container">
        <div id="aaiu-upload-container">
            <a href=" id="aaiu-uploader" class="btn btn-o btn-info push btn-block"><i class="fa fa-folder-open pull-left"></i> Attach</a>
            <div id="aaiu-upload-imagelist"></div>
            <div id="imagelist"></div>
            <div class="clearfix"></div>
            <input type="hidden" name="new_file" id="new_file">
        </div>
    </div>
</div>
<?php echo '<button value="'.$post->ID.'" id="reload-gallery" type="button" class="blank"></button>';?>

<div id="load-gallery">
    <?php require_once(get_template_directory().'attachments.php');?>
</div>
<div id="load-request"></div>