CODEWITHSUNDEEP
c#linqasp.net-mvc-4linq-to-objects
ThunD3eR
ThunD3eR

Reputation: 3456

how to solve the following error: cannot convert from 'int' to 'System.Collections.Generic.IEnumerable<int>?

I am experimentin with jstree and im using an mvc project to populate the tree.

It has worked good so far but now i decied to chnage a property from string to int.

I do this because the property im changingis an ID property and i want to get the highest id from a list that i have and increment it with one.

code:

List<TreeNode> Nodes = getTreenodeList();
var NewId = Nodes.Select(x => x.Id.Max()) +1;

The code above gives me the following error: "cannot convert from 'int' to 'System.Collections.Generic.IEnumerable"

getTreenodeList:

 public static List<TreeNode> getTreenodeList()
        {
            var treeNodes = new List<TreeNode>
            {
                new TreeNode
                {
                    Id = 1,
                    Text = "Root"
                },
                new TreeNode
                {
                    Id = 2,
                    Parent = "Root",
                    Text = "Child1"
                }
                ,
                new TreeNode
                {
                    Id = 3,
                    Parent = "Root",
                    Text = "Child2"
                }
                ,
                new TreeNode
                {
                    Id = 4,
                    Parent = "Root",
                    Text = "Child3"
                }
            };
            // call db and get all nodes. 
            return treeNodes;
        }

And finaly the treeNode class: 

  public class TreeNode
    {
        [JsonProperty(PropertyName = "id")]
        public int Id { get; set; }
        [JsonProperty(PropertyName = "parent")]
        public string Parent { get; set; }
        [JsonProperty(PropertyName = "text")]
        public string Text { get; set; }
        [JsonProperty(PropertyName = "icon")]
        public string Icon { get; set; }
        [JsonProperty(PropertyName = "state")]
        public TreeNodeState State { get; set; }
        [JsonProperty(PropertyName = "li_attr")]
        public string LiAttr { get; set; }
        [JsonProperty(PropertyName = "a_attr")]
        public string AAttr { get; set; }
    }

So far my googeling result gave me a few attempts at this by using firstorDeafut which i found should convert the ienumrable to int but sadly that did not work. I have tried a few other scenarios but none of them have helped.

I can honestly say that I don't really understand what the problem is here so if anyone out there has an answer i would deeply appreciate an explenation aswell.

Thanks!

Upvotes: 3

Views: 5429

Answers (2)

Habib
Habib

Reputation: 223422

This statement (if worked)

Nodes.Select(x => x.Id.Max())

would return an IEnumerable<int> and not a single Int. Replace it with:

Nodes.Select(x => x.Id).Max()

Also Your field Id would be holding a single Value, so to apply Max on it would be wrong.

Your code should be:

var NewId = Nodes.Select(x => x.Id).Max() + 1;

Upvotes: 2

Ehsan Sajjad
Ehsan Sajjad

Reputation: 62498

you have to do like this to get the max id:

var NewId = Nodes.Max(x => x.Id) +1;

For more details and understanding refer:

http://code.msdn.microsoft.com/LINQ-Aggregate-Operators-c51b3869#MaxElements

http://msdn.microsoft.com/en-us/library/bb397947.aspx

http://code.msdn.microsoft.com/101-LINQ-Samples-3fb9811b

Upvotes: 2

Related Questions