使用C#或VB遍历大型嵌套JSON字符串并转换为DataTable

Hey there! I’ve been in your shoes before—nested JSON traversal feels tricky at first, but once you map out the parent-child relationships clearly, it’s totally straightforward. Let’s walk through how to fix this with your MenuObject class and Newtonsoft.Json (Json.NET):

Step 1: Fix Serialization Mapping (Critical!) #

First, make sure your MenuObject class aligns perfectly with your JSON structure. If your JSON uses hyphens (like data-tagname) instead of underscores, add JsonProperty attributes to bridge the gap—this is a super common pitfall that breaks deserialization:

Imports Newtonsoft.Json

Public Class MenuObject
    <JsonProperty("data-tagname")>
    Public Property data_tagname As String
    
    <JsonProperty("data-title")>
    Public Property data_title As String
    
    <JsonProperty("data-menuid")>
    Public Property data_menuid As String
    
    <JsonProperty("data-parentid")>
    Public Property data_parentid As String
    
    <JsonProperty("data-cmsid")>
    Public Property data_cmsid As String
    
    ' Add any other missing properties here
End Class

Step 2: Deserialize JSON to MenuObject List #

Convert your raw JSON string into a list of MenuObject instances first:

Dim jsonString As String = "Your large nested JSON string here"
Dim allMenuItems As List(Of MenuObject) = JsonConvert.DeserializeObject(Of List(Of MenuObject))(jsonString)

Step 3: Build a Parent-Child Lookup Dictionary #

To avoid wasting time searching for child items repeatedly, create a dictionary that maps parent IDs to their corresponding child menus:

' Group menu items by their parent ID for fast lookup
Dim parentChildMap As Dictionary(Of String, List(Of MenuObject)) = 
    allMenuItems.GroupBy(Function(item) item.data_parentid)
                .ToDictionary(Function(g) g.Key, Function(g) g.ToList())

Step 4: Recursively Traverse the Nested Structure #

Use a recursive method to walk through the hierarchy, starting from your root level (adjust the root parent ID to match your data—common values are empty string, "0", or "null"):

' Start traversal from root items (update rootParentId to fit your JSON)
Dim rootParentId As String = "" 
TraverseMenu(parentChildMap, rootParentId, 0)

' Recursive traversal method with hierarchy indentation
Private Sub TraverseMenu(parentChildMap As Dictionary(Of String, List(Of MenuObject)), parentId As String, currentLevel As Integer)
    If parentChildMap.ContainsKey(parentId) Then
        For Each menuItem As MenuObject In parentChildMap(parentId)
            ' Process the item here (example: print with hierarchy indent)
            Console.WriteLine($"{New String("-"c, currentLevel * 2)} {menuItem.data_title} (Menu ID: {menuItem.data_menuid})")
            
            ' Recurse into this item's children
            TraverseMenu(parentChildMap, menuItem.data_menuid, currentLevel + 1)
        Next
    End If
End Sub

Alternative: Traverse Raw JSON Without Full Serialization #

If you don’t need to map everything to MenuObject first, you can use Newtonsoft’s JToken to traverse the raw JSON structure directly:

Dim jsonToken As JToken = JToken.Parse(jsonString)
TraverseJToken(jsonToken, 0)

Private Sub TraverseJToken(token As JToken, currentLevel As Integer)
    Select Case token.Type
        Case JTokenType.Object
            For Each prop As JProperty In token.Children(Of JProperty)()
                Console.WriteLine($"{New String("-"c, currentLevel * 2)} {prop.Name}: {prop.Value}")
                TraverseJToken(prop.Value, currentLevel + 1)
            Next
        Case JTokenType.Array
            For Each item As JToken In token.Children()
                TraverseJToken(item, currentLevel + 1)
            Next
        Case Else
            Console.WriteLine($"{New String("-"c, currentLevel * 2)} {token.ToString()}")
    End Select
End Sub

Quick Troubleshooting Tips #

• Null Properties After Deserialization: Double-check your JsonProperty attributes—mismatched names are the #1 cause here.
• No Root Items Showing: Verify your rootParentId matches the parent ID used for top-level menus in your JSON.
• Infinite Recursion: If your JSON has circular links, add a tracking list to skip already visited menu IDs.

内容的提问来源于stack exchange，提问作者WNM Derek