How to set, Person or Group field to Empty or Null in SharePoint using JSOM

There was a requirement for me, where I need to set/update custom "Person or Group" field column to empty using JSOM

Here is the simple way to do that

Create an empty array

var oUser = new Array();

and pass that empty array to column of type "Person or Group"

listItem.set_item('CustomModifiedBy', oUser)

In the above code snippet, 'CustomModifiedBy' is of type "Person or Group"

How to set SharePoint 2013 user defined date time filed to empty using JSOM

This is a very small post, where I need to set, user defined list column of type date time to null

I looked into the internet and I haven't found anything related to this. To set date time field to empty, just set "null" to that column

For ex:

listitem.set_item('UserModifiedBy', null)

In the above code snippet, UserModifiedBy is of type "Date and Time" which is not a required field and allow nulls

Deleting SharePoint Online Site Collection Programatically

Last week, I got a requirement, where I need to delete some 300+ SPO site collections. Its a tedious process to delete SPO SC manually by going to Site Settings page and click on the link "Delete site".

So I thought is there any better way to delete the SPO site collections programmatically. There is no CSOM api, where we can leverage to delete the Site Collections and one of my colleague asked me to try using HTTPWebRequest approach

Here are the high level steps that he suggested me to do:

1. For one Site Collection, go to site settings page and click on "Delete site" link
2. Once you are on that page, for the delete button click event, do the fiddler trace and capture the all the actions that fiddler is doing for that operation
3. Mimic the same using C# code

I followed the same approach that he has suggested and I am able to delete the SPO site collection

Here are the important things that needs to be remembered when doing this operation

1. First we need to authenticate using SharePoint Online
2. Get Authenticated cookie to avoid redirects
3. Set appropriate request headers
4. Set appropriate POST parameters and url encode the same

Deleting a site collection using Http approach is a three step process:

1. Authenticate using SPO credentials and get the authenticate cookie for the site collection that needs to be deleted
2. Need to get post parameters such as form digest, view state, event target, event validation etc
3. Using the SPO credentials and using the post parameters, created another http web request object that will delete the site collections

Authenticating to SharePoint online

To authenticate to SharePoint online, we need SharePoint client dll's. Refer the following SharePoint client side dlls

1. Microsoft.SharePoint.Client
2. Microsoft.SharePoint.Client.Runtime

The below method is used to authenticate the user using SPO credentials



Getting Authentication Cookie

After authentication, we need to get authenticated cookie for the site collection, that needs to be deleted

The below code is used to get authenticated cookie



We need to add the cookie that got generated to the CookieContainer class, which will be added to the HTTPWebRequest class

Setting up the HttpWebRequest instance

The below code will show how to create HttpWebRequest class and how to pass SPO credentials and how to setup the CookieContainer that has been discussed above



The url for deleting the site collection will be: "site collection url"/_layouts/15/deleteweb.aspx.

For ex: https://your tenant/teams/sitecollectionname/_layouts/15/deleteweb.aspx

For the Http Web Request class, we need to set the following properties. This information we got from the fiddler trace

Method = "POST"
ContentType = "application/x-www-form-urlencoded"
UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.3; WOW64; Trident/7.0; .NET4.0E; .NET4.0C; .NET CLR 3.5.30729; .NET CLR 2.0.50727; .NET CLR 3.0.30729; BRI/2; InfoPath.3)";

Apart from setting the properties, we also need to set some form parameters, the same form parameters that "Delete" button will set on the "deleteweb.aspx"

These form parameters we can get from the fiddler trace

1. __REQUESTDIGEST
2. __VIEWSTATE
3. __EVENTVALIDATION
4. __VIEWSTATEGENERATOR
5. SideBySideToken

In order to get the above form parameters, first we need to get the html source for the deleteweb.aspx and from that html source, we need to scrap the html source to get the above values.

I have written two functions, first function will return the html source and the second function will parse the html source and will get the desired values as discussed above





The below code will show to use the above two methods and set the post parameters for the http web request class



Setting the post data and pass that post data to the web request class



__EVENTTARGET has been hard coded to "ctl00$PlaceHolderMain$ctl07$RptControls$BtnDelete" which we got from the fiddler trace and this can be used as is until unless Microsoft does not change the button name and position in the deleteweb.aspx

The below part of post data has been hard coded which I copied directly from the fiddler trace. Convert the string post data to byte array and pass that information to the request object




 The final step is to get the HttpWebResponse for the http web request that has been created above




If the response string contains, "Working on it", then we can assume that site has been deleted
 

Uploading multiple attachments to the lists using JSOM

In the previous blog post, we have seen how to attach a single file to the list item

In this blog post we will see how we can attach multiple attachments to a list item using JSOM. The following code will work in both SharePoint hosted apps and regular SPO web applications

The following technologies are referred/used in  the blog post

1. jquery.multifile.js
2. jquery
3. SPO client side libraries

Not much information is available in the internet to attach multiple files to the list items.

In your custom form, where you want to attach multiple files, add the following html tags which will facilitate the user to attach multiple files to the list item

As part of this post, we assume that, we have list called "MyList" and in that list we have two list columns called "FirstName" and "LastName"

When we insert data to this list, we also attach multiple list items. The below code snippet will show the simple html that has been created for the user to insert data into the list called "MyList"



As you can see in the above code snippet, I have two html text boxes for FirstName and LastName and a file input control.

To facilitate multi file upload control, I am leveraging "jquery.multifile.js" plugin. If we don't use that plugin, the user will select only one input file for upload

When the user selects multiple files, here is how the UI looks like

 

As you can, with the help of jquery plug in, we can select multiple files. The complete UI will look like this

I also have a submit button and on click of that button, I want to insert a new list item as well as attach as the files that user has selected

On click of btnSubmit, all the files that are selected by the user will be attached to the list item.

Here is the code snippet for the btnSubmit click event. I have written this click event in the jquery document load function



As a first step, loop all the attachments the user as selected and push that information into some javascript array. That javascript array function will just have the file information and not the contents of that file



Create another JSON array, to hold all the values the user has entered such as first name, last name etc. and including the file array that has been created above

data.push({"FirstName": $("#txtFirstName").val().trim(), "LastName": $("#txtLastName").val().trim(), "Files": fileArray});

After this, I have written some function will insert list item also attach the list items also



I am using regular JSOM code for creating the list items. Since attachments has to be inserted  to the newly created item, I need to know the ID to which I need to insert the attachments

So, first I will insert/create the data, get the list id and to that list id, we need to insert attachments


After the getting the list id, I will loop with all the attachments the user has selected. I wont resolve the function, till I insert all the list attachments. If all the attachments are inserted, I will resolve the function

loopFileUpload function need to called recursively till all the list attachments are inserted



As you can see in the above function, loopFileUpload has been called recursively till all the list attachments are inserted

With in the loopFileUpload function, I am calling another function called uploadFile which will associate the list attachment to the id that has been passed to that function



Within the uploadFile function, I am calling another function called, getFileBuffer, will will read the actual contents of the file and pass that information to uploadFile function

We are using REST based approach for inserting the list attachments as REST will allow to upload upto 2 GB of file

Here is the url that needs to be used to access the list item id to which we need to insert the list attachment




Here is the complete source code of the page that I used for this blog post



Here is the snapshot of the list item that got created using this code with multiple attachments