ASP.NET MVC: Save multiple values on autocomplete - asp.net

Question

I have a mysql database with the tables "deliverables", "tags" and "deliverables_has_tags". I want to link tags to a deliverable.
This is what I do in my javascript file:
<script type="text/javascript" language="javascript">
$(function () {
var object = {};
$.ajax({
type: "GET",
url: "/Deliverable/Tags",
dataType: "json",
success: function (data) {
object.tags = data;
}
});
function split(val) {
return val.split(/,\s*/);
}
function extractLast(term) {
return split(term).pop();
}
$("#tags")
// don't navigate away from the field on tab when selecting an item
.bind("keydown", function (event) {
if (event.keyCode === $.ui.keyCode.TAB &&
$(this).data("ui-autocomplete").menu.active) {
event.preventDefault();
}
})
.autocomplete({
minLength: 0,
source: function (request, response) {
// delegate back to autocomplete, but extract the last term
response($.ui.autocomplete.filter(
object.tags, extractLast(request.term)));
},
focus: function () {
// prevent value inserted on focus
return false;
},
select: function (event, ui) {
var terms = split(this.value);
// remove the current input
terms.pop();
// add the selected item
terms.push(ui.item.value);
// add placeholder to get the comma-and-space at the end
terms.push("");
this.value = terms.join(", ");
return false;
}
});
});
</script>
I can add multiple tags in my textbox.
But now I want to save this in my repository.
In my Action method in controller:
repository.AddDeliverable(model.Title, model.Description, model.UsernameID, data, datatwo, model.VideoUrl, model.AfstudeerrichtingID, model.ProjectID);
Tags action:
public JsonResult Tags()
{
var data = (repository.GetTags()).ToArray();
return Json(data, JsonRequestBehavior.AllowGet);
}
In my repository:
public IQueryable<string> GetTags()
{
return from tag in entities.tags
orderby tag.tag_name
select tag.tag_name;
}
I have no clue how to save this in my database.
Can anybody help me?

Answer 1

If I correctly understood your question, you have implemented your tag handling as follows:
There is MVC action method that returns the view with input placeholder containing no data
The placeholder itself is probably input type=text with id=tags
On 'dom ready' you fire ajax request to retrieve your tags from database, json-serialized as array; when it arrives you store it to tags variable (no error handling(!))
At the same time you decorate your input with jqueryui autocomplete that reacts on user input and returns items from the tags variable
Since input already contains tags (comma separated), your filter is first letters of the last tag
So, you have a situation when user has input a few comma separated tags (probably some of them can be new) and now wants to save it to the database. For each input, if that is a known tag you have to store it to "deliverables_has_tags". If there is a new tag, you have to store it both to "tags" and "deliverables_has_tags".
Most common scenario would be having a 'Save' button to start saving process.
Let's analyze what you have to do in the process.
1) Button click
On button click you use js to convert your comma separated tags string
using logic like split(term) to the array, and serialize it. You can
do serialization using serializeArray and manually create JSON
object, or serialize the whole form using
$('#yourForm').serialize(). I would choose the first option
because that way I get more control over JSON format and avoid
problems with MVC default model binder.
2) Ajax call
When the JSON object is ready to be sent, you fire an ajax POST
request to your MVC POST action method. When you save state always
avoid GET because new versions of browsers can scan thru your page and
actively preload urls using GET requests. You don't want this here. Of
course, use your data as a data-parameter in the ajax call.
3) Action method
When the request arrives, you have to process it in your controller
using a new action method. Typically in this case you will have
something like public JsonResult SaveTags(SaveTagsModel saveTags) {
... } which saves tags using your repository and returns result that
says something like 'OK' or 'ERROR' (sth like
response.isSaved=true/false). Tricky part can be designing view model
according to your JSON object - this could help. And regarding
collections this could be valuable info.
When saving, use transaction to ensure everything is saved at once.
First check if each tag exists in the database and insert those who
don't exist. After that, check for each tag if there is appropriate
n-n relation in deliverables_has_tags and insert it if there isn't.
I believe that you should use same repository encapsulation for both
operations.

Answer 2

In the post action, include FormCollection collection as argument and gather your tags from that. There is no automatic way. You could implement some custom model binding, but that is probably not worth the effort.