使用VB.Net读取JSON对象及Newtonsoft循环遍历JSON的技术求助

Got it, let's walk through exactly how to do this—whether your JSON is a simple array or a nested object, I'll cover the common scenarios and share actionable code snippets.

First, Basic Setup #

Make sure you have the Newtonsoft.Json (Json.NET) NuGet package installed in your project. If not, you can install it via the Package Manager Console:

Install-Package Newtonsoft.Json

Scenario 1: JSON is a Simple Array of Objects #

Let's say your JSON looks like this (a list of items with a Name field):

[
  { "Name": "Alice", "Role": "Admin" },
  { "Name": "Bob", "Role": "User" },
  { "Name": "Charlie", "Role": "User" }
]

Here's how to parse it, loop through each item, and save the names to a database (using SQL Server as an example—adjust for your database type):

using Newtonsoft.Json.Linq;
using System.Data.SqlClient;

// Your raw JSON string
string jsonData = @"[
  { ""Name"": ""Alice"", ""Role"": ""Admin"" },
  { ""Name"": ""Bob"", ""Role"": ""User"" },
  { ""Name"": ""Charlie"", ""Role"": ""User"" }
]";

// Parse the JSON into a JArray
JArray itemsArray = JArray.Parse(jsonData);

// Loop through each object in the array
foreach (JObject item in itemsArray)
{
    // Safely get the Name value (avoid null reference errors with ?.)
    string name = item["Name"]?.ToString();
    
    // Skip empty or null names to avoid invalid database entries
    if (string.IsNullOrWhiteSpace(name))
        continue;

    // Save to database using parameterized queries (critical to prevent SQL injection!)
    using (SqlConnection connection = new SqlConnection("Your_Database_Connection_String"))
    {
        connection.Open();
        string insertQuery = "INSERT INTO Your_Table_Name (Name) VALUES (@Name)";
        
        using (SqlCommand command = new SqlCommand(insertQuery, connection))
        {
            command.Parameters.AddWithValue("@Name", name);
            command.ExecuteNonQuery();
        }
    }
}

Scenario 2: JSON Has a Nested Array #

If your JSON is wrapped in a parent object (like a Users array inside a root object):

{
  "Company": "Tech Corp",
  "Users": [
    { "Name": "Diana", "Department": "Engineering" },
    { "Name": "Eve", "Department": "Marketing" }
  ]
}

Just adjust the parsing step to target the nested array:

string nestedJson = @"
{
  ""Company"": ""Tech Corp"",
  ""Users"": [
    { ""Name"": ""Diana"", ""Department"": ""Engineering"" },
    { ""Name"": ""Eve"", ""Department"": ""Marketing"" }
  ]
}";

// Parse root object first
JObject rootObject = JObject.Parse(nestedJson);
// Get the nested Users array
JArray usersArray = (JArray)rootObject["Users"];

// The rest of the loop and database code is identical to Scenario 1
foreach (JObject user in usersArray)
{
    string name = user["Name"]?.ToString();
    if (!string.IsNullOrWhiteSpace(name))
    {
        // Save to database...
    }
}

Bonus: Use Strongly-Typed Classes (Cleaner for Complex JSON) #

If you have a consistent JSON structure, you can create a C# class to deserialize the JSON directly, which makes the code more readable:

using Newtonsoft.Json;

// Define your class to match the JSON structure
public class User
{
    public string Name { get; set; }
    public string Department { get; set; } // Optional, if you need other fields
}

// Deserialize the JSON into a list of User objects
List<User> users = JsonConvert.DeserializeObject<List<User>>(jsonData);

// Loop through the strongly-typed list
foreach (User user in users)
{
    if (!string.IsNullOrWhiteSpace(user.Name))
    {
        // Save to database...
    }
}

Key Notes to Remember #

• Always use parameterized queries: Never concatenate user input (or JSON values) directly into SQL strings—this is a massive security risk (SQL injection).
• Handle null/empty values: Add checks like string.IsNullOrWhiteSpace(name) to avoid saving invalid data to your database.
• Adjust for your database: If you're using PostgreSQL, MySQL, etc., replace the SqlConnection/SqlCommand with the appropriate client classes (e.g., NpgsqlConnection for PostgreSQL).

Hope this solves your problem! If your JSON structure is more complex than these examples, feel free to share a snippet and I can tweak the code to match.

内容的提问来源于stack exchange，提问作者Bill