How do I map complex json to model in ASP.Net MVC

Question

I've following JSON:

var QuestionTemplate = {
    Name: "Simple addition",
    MathML: "mathML goes here",
    Expression: "a+b",
    QType: "mcq",
    Rules: {
        a: {//a is variable from expression(a+b) 
            variableType: "Single Digit",
            min: "1",
            max: "6"
        },
        b: {//b is variable from expression(a+b)
            variableType: "Two Digit",
            min: "20",
            max: "80"
        }
    }
};

In rules "a" and "b" are variables from expression "a+b". If expression is a+b+c, there will be three variables a,b and c.

Now I want to map above json to my model in MVC.

What I've tried so far:

Model:

public class QuestionTemplateModel
{
    [BsonId]
    [BsonRepresentation(BsonType.ObjectId)]
    public string Id { get; set; }
    public string Name { get; set; }
    public string MathML { get; set; }
    public string Expression { get; set; }
    public string QType { get; set; }
    public Rules Rules { get; set; }

}

public class Rules
{
    public List<variable> variable { get; set; }
}

public class variable
{
    public List<VariableDetails> VariableDetails { get; set; }
}

public class VariableDetails
{
    public string variableType { get; set; }
    public string min { get; set; }
    public string max { get; set; }
}

But when I send my json to model Rules is null, where as Name, MathML, Expression, QType are mapped properly. How I need to structure my model. What mistake I am doing.

In your JSON rules property is a collection type, while in your QuestionTemplate model, its an single object — Mox Shah
– Mox Shah, Commented Oct 16, 2014 at 11:02
Are you really quite sure that out of the many answers given on the same topic (model binding) on SO before, not one provides the information needed to solve your problem as well? — Oskar Lindberg
– Oskar Lindberg, Commented Oct 16, 2014 at 11:17

mlinth · Accepted Answer · 2014-10-16 11:11:27Z

2

I don't think you need so many nested objects - a dictionary should work... [EDIT] you need to create the dictionary, too. The dictionary keys will be your variable names (a, b).Try this:

public class QuestionTemplateModel
{
    [BsonId]
    [BsonRepresentation(BsonType.ObjectId)]
    public string Id { get; set; }
    public string Name { get; set; }
    public string MathML { get; set; }
    public string Expression { get; set; }
    public string QType { get; set; }
    public Dictionary<string, VariableDetails> Rules = new Dictionary<string, VariableDetails>() { get; set; }

}



public class VariableDetails
{
    public string variableType { get; set; }
    public string min { get; set; }
    public string max { get; set; }
}

edited Oct 16, 2014 at 11:11

answered Oct 16, 2014 at 11:06

mlinth

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Comments

Mox Shah · Accepted Answer · 2014-10-16 11:06:36Z

0

In your bellow code

a: {//a is variable from expression(a+b) 
        variableType: "Single Digit",
        min: "1",
        max: "6"
    },
    b: {//b is variable from expression(a+b)
        variableType: "Two Digit",
        min: "20",
        max: "80"
    }

a: and b: will not match with any property so it won't bind that Rules Property, what you can do is remove that a: and b: name and format your JSON in following way

{
        variableType: "Single Digit",
        min: "1",
        max: "6"
    },
    {
        variableType: "Two Digit",
        min: "20",
        max: "80"
    }

answered Oct 16, 2014 at 11:06

Mox Shah

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1 Comment

Mox Shah Over a year ago

Above ans by @mlinth would be a better option, it should work, if JSON format is in your control then try above code in my ans.

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