SVG data not get on form submit - php

Question

I want save SVG data in a database. I will try with a simple submit and also with AJAX. I also set content-type="image/svg-xml"
I will check data with print_r($_POST); SVG Content displayed here when I will try to store on db svg value as null.
<?php echo form_open('admin/shape/add',array('class' => 'form-horizontal', 'name' => 'catfrm', 'id' => 'catfrm')); ?>
<div class="box-body">
<div class="col-md-8">
<div class="form-group">
<label class="col-sm-2 control-label">Title <span class="error">*</span></label>
<div class="col-sm-10">
<input type="text" name="title" value="" id="title" class="form-control" />
</div>
</div>
<!-- form-group -->
</div>
<div class="col-md-8">
<div class="form-group">
<label class="col-sm-2 control-label">Content <span class="error">*</span></label>
<div class="col-sm-4" id="shape_priview" height="30px">
<svg xmlns="http://www.w3.org/2000/svg" version="1.1" viewBox="0,0,100,100"><polygon points="50 0, 0 100, 100 100"></polygon></svg>
</div>
<div class="col-sm-6">
<textarea name="content" id="shape_content" class="form-control"><svg xmlns="http://www.w3.org/2000/svg" version="1.1" viewBox="0,0,100,100"><polygon points="50 0, 0 100, 100 100"></polygon></svg></textarea>
</div>
</div>
<!-- form-group -->
</div>
</div>
<div class="box-footer" align="center">
<button type="submit" class="btn btn-success">Add</button>
<button type="reset" class="btn btn-dark" onclick="window.location.href = '<?php echo site_url('admin/shape'); ?>'">Cancel</button>
</div>
<?php echo form_close();?>
$(document).ready(function() {
$("#shape_content").on("change keyup paste", function() {
$("#shape_priview").text('');
var shape_content = $("#shape_content").val();
$("#shape_priview").html(shape_content);
});
$("#catfrm").validate({
rules: {
title: {
required: true,
}
},
messages: {
title: {
required: "Title is required",
}
},
submitHandler: function(form) {
$("#catfrm").submit(function(event) {
event.preventDefault();
var content = $("#shape_content").val();
var title = $("#title").val();
alert(content);
$.ajax({
type: "post",
url: "<?php echo site_url('admin/shape/add'); ?>",
data: {
"title": title,
"content": content
},
contentType: "application/json",
success: function(responseData, textStatus, jqXHR) {
alert(responseData);
alert("data saved")
},
error: function(jqXHR, textStatus, errorThrown) {
console.log(errorThrown);
}
})
});
}
});
});