C# - object to string truncates decimal value .0

Question

I am trying to extract currency value from Json using Newtonsoft json library. The SelectToken method gives me data as object. I am converting it to string and inserting in DB. When the value is say 9.9 I get exact value as string but when there is 9.0 then ToString() truncates decimal values and returns me only 9. I did lot of research but did not find any answer.

I am expecting below values as string from object. I don't want additional decimal places or remove all. I need it as it is.

Object => expected string

9 => 9

9.0 => 9.0

9.00 => 9.00

9.9 => 9.9

9.99 => 9.99

Edit:

Simple question. If object a has value 9.0 then I want same value 9.0 as string.

similarly if it has 9 then I want string 9

if it has 9.90 then I want 9.90 as string

if it has 9.99 then I want 9.99 as string

I hope I am clear this time.

Answer 1

If you use JObject.Parse, in order to do what you need, your value must be a string. If it's a floating point value, you won't get its decimals. Check out this example:

string json = "{ sValue1: '9.00', sValue2: '9.0000', dValue1: 9.00, dValue2: 9.0000 }";

JToken token = JObject.Parse(json);

// prints 9.00, or 9,00 if comma is your decimal separator
Console.WriteLine((decimal)token.SelectToken("sValue1"));
// prints 9.00 regardless of your decimal separator
Console.WriteLine((string)token.SelectToken("sValue1"));

// prints 9.0000, or 9,0000 if comma is your decimal separator
Console.WriteLine((decimal)token.SelectToken("sValue2"));
// prints 9.0000 regardless of your decimal separator
Console.WriteLine((string)token.SelectToken("sValue2"));

// All these print 9
Console.WriteLine((decimal)token.SelectToken("dValue1"));
Console.WriteLine((string)token.SelectToken("dValue1"));
Console.WriteLine((decimal)token.SelectToken("dValue2"));
Console.WriteLine((string)token.SelectToken("dValue2"));

Casting as double always removes trailing zeros.

Summarizing, these are the options:

1. String => string: exact outcome
2. String => decimal: exact outcome if the decimal separator matches
3. String => float/double: without trailing zeros
4. Float => whatever: without trailing zeros

Just for the record, decimal data type keeps track of the precision used, so it knows if there are trailing zeros.

If you already have a class for all the properties in the JSON string, you can use JsonConvert.DeserializeObject, which keeps the trailing zeros if you store those in a string even though if they come as float. You can see this in CodingYoshi's answer.

PS: As others mentioned, numeric values should be stored as such in the DB, but that's for another question.

Answer 2

In the comment to your question you said:

If I use this code price.SelectToken("ListPrice", false).ToString() then it gives me only 9 only. I understand 9.0 is same as 9 but my client wants it as it it is

In the comments various people suggested to keep it as numeric and that is good advice. However, if your client wants it that way, then that is how it has to be. The easiest solution would be to deserialize it into a string instead of a numeric type. For example imagine you have this JSON:

{
    Unit: 15.0000,
    Value: 14.000
}

If you deserialize it into the following type:

public class ItemSize
{
    public string Unit { get; set; }
    public double Value { get; set; }
}

then Unit, because it is a string, will keep all the decimals but Value will not. So just make your property a string type and JSON.NET will take care of it for you. You can test the above with this code:

var val = JsonConvert
    .DeserializeObject<ItemSize>("{ Unit: 15.0000, Value: 14.000 }");