Edit: It's been almost 5 years and I don't think this is the way to go. The client should post the data in the correct numerical format. With current frameworks like React or Angular, or with a proper architecture and error handling & validation, i think this is almost a non-problem.
But if anyone wishes to flex their Json.NET muscles, feel free to check the answers.
I have a MVC application and I handle some JSON in it. That's simple. I have this simple piece of code in my ModelBinder:
return JsonConvert.DeserializeObject(jsonString, bindingContext.ModelType, new JsonSerializerSettings
{
NullValueHandling = NullValueHandling.Ignore,
MissingMemberHandling = MissingMemberHandling.Ignore,
Formatting = Formatting.None,
DateFormatHandling = DateFormatHandling.IsoDateFormat,
FloatParseHandling = FloatParseHandling.Decimal
});
And it works flawlessly.
Well, sort of.
Let's say I have this class:
public class MyClass
{
public decimal MyProp { get; set; }
}
If I try to deserialize this json:
{MyProp: 9888.77}
Of course it works, since 9888.77 is a Javascript float value. I think.
But I have a masked input for money in my page that makes the JSON look like this (sorry about my english):
{MyProp: 9.888,77 }
AAAND, it fails. It says that it Could not convert string to decimal.
Ok, that's fair. It is not a JS float, but Convert.ToDecimal(9.888,77) works the way I want.
I've read some tutorials on the internet about custom deserializers, but its inviable for me to define a custom deserializer for every single class I have in my application.
What I want is to simple redefine the way JSON.Net converts a string to a decimal property, in any class i'll ever want to deserialize to. I want to inject the Convert.ToDecimal function in the process of converting decimals, when the current converter doesn't work.
Is there a way I could do it?
I thought there was a way to do it, so I changed my code a little bit.
JsonSerializer serializer = new JsonSerializer
{
NullValueHandling = NullValueHandling.Ignore,
MissingMemberHandling = MissingMemberHandling.Ignore,
Formatting = Formatting.None,
DateFormatHandling = DateFormatHandling.IsoDateFormat,
FloatParseHandling = FloatParseHandling.Decimal,
};
return serializer.Deserialize(new DecimalReader(jsonStr), bindingContext.ModelType);
And created this class:
public class DecimalReader : JsonTextReader
{
public DecimalReader(string s)
: base(new StringReader(s))
{
}
public override decimal? ReadAsDecimal()
{
try
{
return base.ReadAsDecimal();
}
catch (Exception)
{
if (this.TokenType == JsonToken.String)
{
decimal value = 0;
bool convertible = Decimal.TryParse(this.Value.ToString(), out value);
if (convertible)
{
return new Nullable<decimal>(value);
}
else { throw; }
}
else
{
throw;
}
}
}
}
But it is very ugly: it executes what I want only when it crashes, and depends on base.ReadAsDecimal() crashing. It couldn't be more ugly.
And doesn't work :Error converting value 1.231,23 to type 'System.Nullable1[System.Decimal]'. Path 'MyProp', line X, position Y.
The value itself is being converted, but perhaps for some reason it still tries to put the string 1.231,23 into a decimal.
So, is there a way to do it properly?
