Error while reading a json file in C#

Question

User1839056048 posted

Hi,

I want to read data from a json file in asp.net

my jsonfile is user.json

{
  "id": 123,
  "name": "Mukesh Kumar",  
    "street": "El Camino Real",
    "city": "New Delhi",
    "zipcode": 95014 
	}

if I add square brackets before and after  in json file ,it will not read.

my code

private string jsonFile = @"D:\MVCExampl\JsonExample\JsonExample\User.json";  
        protected void Page_Load(object sender, EventArgs e)
        {

            var json = File.ReadAllText(jsonFile); 
            
            try
            {
                var jObject = JObject.Parse(json);
                
               if (jObject != null)
                 {
                     string strMsg = "<table style='border=1px solid blue; rules='All'; cellspacing='0'; border-collapse:collapse;'>";
                     strMsg += "<tr><td>Id</td><td>Name</td><td>Street</td><td>City</td><td>ZipCode</td></tr>";
                     strMsg += "<tr>";
                     
                         strMsg += "<td>" + jObject["id"].ToString() + "</td>";
                     strMsg += "<td>" + jObject["name"].ToString() + "</td>";
                     strMsg += "<td>" + jObject["street"].ToString() + "</td>";
                     strMsg += "<td>" + jObject["city"].ToString() + "</td>";
                     strMsg += "<td>" + jObject["zipcode"].ToString() + "</td>";
                    
               
                     strMsg += "</tr>";
                     strMsg += "</table>";
                     Response.Write(strMsg);
               }
                 


            }
            catch (Exception ex)
            { 
            
            }
        }

this is working fine .

my requirement is

   1. if there is more than one record in json file how to write a for loop.

2. how to add another record in that json file.

I have tried to add a record by adding a comma and a square bracket at at starting and end of file.

but it doesn't read

How to solve this

Regards

Baiju

Answer 1

User475983607 posted

It's much easier to assist when the actual code that causes the issue is provided along with the steps to reproduce.  However, the code has several questionable design approaches.  The biggest is the empty catch block.  You're hiding the valuable exception error message from yourself.  Given the code above, we can only guess where the bug is located.

The other issue is you are reading the JSON stream as a string rather than populating a type.  See the the NewtonSoft docs which shows how to read JSON from a file with example code.  I prefer to use strong types... Anyway, the openly published docs are very clear on the subject.

https://www.newtonsoft.com/json/help/html/DeserializeWithJsonSerializerFromFile.htm

https://www.newtonsoft.com/json/help/html/ReadJson.htm

Answer 2

User-893317190 posted

Hi klbaiju,

If your json file has more than one records,you could also use jtoken.

 protected void Page_Load(object sender, EventArgs e)
        {
       String text=     File.ReadAllText(Server.MapPath("/json/user.json"));

          JToken token =  JToken.Parse(text);
           
            foreach (JObject item in token)
            {
                Response.Write("user:" + "<br/>");
                Response.Write(item["id"] + "<br/>");
                Response.Write(item["name"] + "<br/>");
                Response.Write(item["street"] + "<br/>");
                Response.Write(item["zipcode"] + "<br/>");
            }
     
        }

My json.

[
  {
    "id": 123,
    "name": "Mukesh Kumar",
    "street": "El Camino Real",
    "city": "New Delhi",
    "zipcode": 95014
  },
  {
    "id": 456,
    "name": "Mkesh Kumar",
    "street": "l Camino Real",
    "city": "Nw Delhi",
    "zipcode": 944
  }

]

The result.

Best regards,

Ackerly Xu

Answer 3

User1839056048 posted

Dear friend,

thanks for your reply.the code is working fine.following is the working code for displaying in table format

 String text = File.ReadAllText(@"D:\MVCExampl\JsonExample\JsonExample\User.json");

            JToken token = JToken.Parse(text);
            if (token.Count() > 0)
            {
                string strMsg = "<table style='border=1px solid blue; rules='All'; cellspacing='0'; border-collapse:collapse;'>";
                strMsg += "<tr><td>Id</td><td>Name</td><td>Street</td><td>City</td><td>ZipCode</td></tr>";
                foreach (JObject item in token)
                {

                    strMsg += "<tr>";
                    strMsg += "<td>" + item["id"].ToString() + "</td>";
                    strMsg += "<td>" + item["name"].ToString() + "</td>";
                    strMsg += "<td>" + item["street"].ToString() + "</td>";
                    strMsg += "<td>" + item["city"].ToString() + "</td>";
                    strMsg += "<td>" + item["zipcode"].ToString() + "</td>";
                    strMsg += "</tr>";

                }
                strMsg += "</table>";
                Response.Write(strMsg);
            }

can you share the code for inserting,update and delete

Regards

Baiju

Answer 4

User-893317190 posted

Hi klbaiju,

Insert 

  String text=     File.ReadAllText(Server.MapPath("/json/user.json"));

          JToken token =  JToken.Parse(text);


            JObject jObject = new JObject(new JProperty("id", 12), new JProperty("name", "name"), new JProperty("street", "street"), new JProperty("city", "city"), new JProperty("zipcode", 954));
            ((JArray)token).Add(jObject);
  File.WriteAllText(Server.MapPath("/json/user.json"), token.ToString());

Delete 

 String text=     File.ReadAllText(Server.MapPath("/json/user.json"));

          JToken token =  JToken.Parse(text);
((JArray)token).Remove(((JArray)token).Where(j => j["id"].ToString() == "123").Single());
// select the object with id 123 using link and remove it 
 File.WriteAllText(Server.MapPath("/json/user.json"), token.ToString());

Update.

 String text=     File.ReadAllText(Server.MapPath("/json/user.json"));

          JToken token =  JToken.Parse(text);
((JArray)token).Where(j => j["id"].ToString() == "12").Single()["name"]="new name";
            File.WriteAllText(Server.MapPath("/json/user.json"), token.ToString());

You could go to official site to study more

https://www.newtonsoft.com/json/help/html/Introduction.htm

Best regards,

Ackerly Xu