Question 278149 in Json Question posted in
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.NET JSON: check structure

I know I can check wether is a string is a valid JSON-formatted string using parsing functions and catching exceptions. But what I need is a bit more than that too.

I need to check if a string that comes in abides a certain model in JSON format.

E.g. I have this class

class MyClass {
  public String Key1 { get; set; }
  public List<MyClass2> Key2 { get set; }
  public int Key3 { get set; }
}

class MyClass2 {
  public int Key4 { get; set; }
}

and the following string s1 comes in

{
  "Key1": "Hello",
  "Something": "World",
  "Key2": [
     { "Key4": 100 }
  ],
  "Key3": 2
}

Although s1 IS a validly formatted JSON string, it does not abide by the structure of MyClass1 since it has a property Something that is not a property of MyClass1. If however I receive the following string s2

{
  "Key1": "Hello",
  "Key2": [
     { "Key4": 100 }
  ]
}

then this would be valid for me even though there are properties missing. Formally put, the given properties must be exactly a subset of the model’s properties.

How could I achieve this in .NET? Note that MyClass could be generic so I cannot hard check for names.

Tags:

2

Answers


  1. 0

    Simply, you could make a function to foreach on each property of your incoming object and if the whole object doesn’t match your ‘MyClass’ return "False"

    Kind Regards

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  2. 0

    JSON Schema is a thing and, I would argue, should be used to validate JSON.

    There are a number of different implementations and a few of them are for .NET. There’s even one from NewtonSoft – JSON.Net Schema although it’s not completely free!

    An example using JsonSchema.Net

    using Json.Schema;
using Json.Schema.Generation;
using Json.Schema.Serialization;

var json = @"{
  ""Key1"": ""Hello"",
  ""Something"": ""World"",
  ""Key2"": [
     { ""Key4"": 100 }
  ],
  ""Key3"": 2
}";

var schema = new JsonSchemaBuilder()
    .FromType<MyClass>()
    // Fail the validation if there any additional properties.
    .AdditionalProperties(JsonSchema.False)
    .Build();

var evaluationResults = schema.Evaluate(System.Text.Json.JsonDocument.Parse(json));

if (!evaluationResults.IsValid){
    // Log/throw an error here.
}
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