Vb.net 9 中的产量

Question

I want to use the C# yield in VB.net 9 but it is not working.

private static IEnumerable<JToken> AllChildren(JToken json)
{
    foreach (var c in json.Children())
    {
        yield return c;
        foreach (var cc in AllChildren(c))
        {
            yield return cc;
        }
    }
}

this is the c# code and it is converted to VB.net using the online tools but it is not giving me the same result.

Private Shared Function AllChildren(json As JToken) As IEnumerable(Of JToken)
For Each c As var In json.Children()
    yield Return c
    For Each cc As var In AllChildren(c)
        yield Return cc
    Next
Next
End Function

Can anybody help me translate this?

Answer 1

It took me a while to get it right, but this is what you need:

Private Shared Iterator Function AllChildren(json As JToken) As IEnumerable(Of JToken)
    For Each c As JToken In json.Children()
        Yield c
        For Each cc As JToken In AllChildren(c)
            Yield  cc
        Next
    Next
End Function

---

Since you are working in VB9 and you can't use iterators there is a very easy and neat option that you can use.

You just need to NuGet "Ix-Main" to get the Microsoft Reactive Framework team's "Interactive Extensions" - a bunch of handy IEnumerable<T> operators.

Then you can try this code:

Private Shared Function AllChildren2(json As JToken) As IEnumerable(Of JToken)
    Return EnumerableEx.Expand(json.Children(), Function (c) c.Children())
End Function

Answer 2

Create a C# class project, add json.net package/reference to the project. Add the following class

using Newtonsoft.Json.Linq;
using System.Collections.Generic;

namespace NewtonExtensions
{
    public static class Extensions
    {
        private static IEnumerable<JToken> AllChildren(JToken json)
        {
            foreach (var c in json.Children())
            {
                yield return c;
                foreach (var cc in AllChildren(c))
                {
                    yield return cc;
                }
            }
        }
    }
}

Compile the above project. In the current project, add a reference to the project above. Where the extension method is to be used, add a using statement.

Underlying thing here is unless using an older Express version of Visual Studio we can easily share code between languages.

EDIT Here is the same as above as an extension method

using Newtonsoft.Json.Linq; using System.Collections.Generic;

namespace NewtonExtensions
{
    public static class Extensions
    {
        public static IEnumerable<JToken> AllChildren(this JToken json)
        {
            foreach (var c in json.Children())
            {
                yield return c;
                foreach (var cc in AllChildren(c))
                {
                    yield return cc;
                }
            }
        }
    }
}

Example usage in vb.net where I use xml literal for the json string. You would read in the json as normally would say from a file etc.

The Imports NewtonExtensions is in a C# class project with a namespace of NewtonExtensions.

I show two methods to iterate data after using the language extension method.

Imports NewtonExtensions
Imports Newtonsoft.Json.Linq

Public Class Form1

    Private Sub Button1_Click(sender As Object, e As EventArgs) _
        Handles Button1.Click

        Dim jsonString As String =
            <json>
{
    "ADDRESS_MAP":{

        "ADDRESS_LOCATION":{
            "type":"separator",
            "name":"Address",
            "value":"",
            "FieldID":40
        },
        "LOCATION":{
            "type":"locations",
            "name":"Location",
            "keyword":{
                "1":"LOCATION1"
            },
            "value":{
                "1":"United States"
            },
            "FieldID":41
        },
        "FLOOR_NUMBER":{
            "type":"number",
            "name":"Floor Number",
            "value":"0",
            "FieldID":55
        },
        "self":{
            "id":"2",
            "name":"Address Map"
        }
    }
}                
            </json>.Value


        Dim results As JObject = JObject.Parse(jsonString)

        Console.WriteLine("Example 1")
        For Each item As KeyValuePair(Of String, JToken) In results
            Console.WriteLine(item.Key)
            Dim test = item.Value.AllChildren
            For Each subItem In test
                Console.WriteLine(subItem)
                Console.WriteLine()
            Next
        Next
        Console.WriteLine(New String("-"c, 50))
        Console.WriteLine("Example 2")
        results.Cast(Of KeyValuePair(Of String, JToken)) _
            .ToList.ForEach(
                Sub(v)
                    Console.WriteLine(v.Key)
                    Console.WriteLine(v.Value)
                End Sub)


    End Sub
End Class