Adding a sub-task to a task in sharepoint online with c# (using Microsoft.SharePoint.Client)

Question

I have managed to add tasks in Sharepoint online with c#, where I am struggling (maybe for the lack of the better search terms is the following):

How do I add a sub-task to an existing task/ assign a child task to a parent?

The answer seems to lay within the ParentID field, which shows a connection to another task, when entered manually online through the Sharepoint task list.

the field, in that case, shows for the child node the following entry:

-       [12]    {[ParentID, Microsoft.SharePoint.Client.FieldLookupValue]}&nbsp;System.Collections.Generic.KeyValuePair<string, object>
        Key "ParentID"  string
-       Value   {Microsoft.SharePoint.Client.FieldLookupValue}  object {Microsoft.SharePoint.Client.FieldLookupValue}
        LookupId    60  int
        LookupValue "60"    string

        TypeId  "{f1d34cc0-9b50-4a78-be78-d5facfcccfb7}"    string

I have the ID (eg 60) for the parent node to be and I understand the TypeID to be fix from research on the internet (hope my research on this is correct). I think the key might be the use of the KeyValuePair and assign the result to ParentID. This is my code on:

var list = new List<KeyValuePair<string, string>>() {
new KeyValuePair<string, string>("60", "f1d34cc0-9b50-4a78-be78-d5facfcccfb7"), }; 

listItem["Title"] = "do something";
listItem["ParentID"] = list;
listItem.Update();
context.ExecuteQuery();

The result I get or more precise the exception thrown is {"Unknown Error"}.

I am now clueless on where to turn to, or what to do next, do you have an idea? Is the idea of the KeyValuePair even the right one?

Answer 1

Sample code for your reference.

using (var clientContext = new ClientContext(siteUrl))
            {
                clientContext.Credentials = new SharePointOnlineCredentials(login, securePassword);
                List myList = clientContext.Web.Lists.GetByTitle("MyTask");

                ListItemCreationInformation listItemCreationInformation = new ListItemCreationInformation();
                ListItem newItem = myList.AddItem(listItemCreationInformation);
                newItem["Title"] = "subTask";
                newItem["Body"] = "body";
                FieldLookupValue lookupParent = new FieldLookupValue();
                //hardcode for test purpose
                lookupParent.LookupId = 3;
                newItem["ParentID"] = lookupParent;
                newItem.Update();
                clientContext.ExecuteQuery();
}