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Using a REST Api, how to include "any kind of json" in my typed request model?

I am using .NET Framework and ASP.NET Core to create a REST web Api.
This web api has a call that gets a request model to save data and some call that later retrieves the data.
Most of the data is structured information I need in the backend and it is saved into different fields and tables in the database. On retrieval it is loaded from those tables and returned.
This all works.
However, I now have a requirement where the caller wants to save and later retrieve arbitrary data (lets just say a random json) as one of those fields. I can save and load json from the database that is not a problem, my problem is to build the web api model for my request.
[HttpPost]
public IActionResult Save([FromBody] ApiCallRequestModel request)
{
// ...
}
public sealed class ApiCallRequestModel
{
// structured, well known information
public int? MaybeSomeNumber { get; set; }
[Required]
public string SomeText { get; set; }
[Required]
public SubModel SomeData { get; set; }
// one field of unknown json data
public ??? CustomData { get; set; }
}
I could think of dynamic or maybe even ExpandoObject or JObject to try and I might, but I would like a solution that works because it's best practice, not just because I tried and it didn't fail today with my simple tests.
If everything else fails, I could just make the field a string and tell the client to put serialized json into it. But that's a workaround I would see as a last resort if this question yields no answers.
It has proven to be extremly hard to google this topic, since all words I would use lead me to pages explaining Json serialization of my request model itself. I know how that works and it's not a problem. The mix of structured data and free json is what I cannot find out from a somewhat authorative source.
So what type would you use here, what is the best practice for receiving arbitrary json in one property of your model?

So to sum this up, as suggested I used a JToken from the Json.NET nuget package, since I already had that package in my project.
[HttpPost]
public IActionResult Save([FromBody] ApiCallRequestModel request)
{
// ...
}
public sealed class ApiCallRequestModel
{
// structured, well known information
public int? MaybeSomeNumber { get; set; }
[Required]
public string SomeText { get; set; }
[Required]
public SubModel SomeData { get; set; }
// one field of unknown json data
public JToken CustomData { get; set; }
}
Works like a charm.

Passing List object and int to web api

I have a web api core project that if I send just the list parameter than the API receives the values, however if I send both parameters that the controller is looking for then both parameters are seen as null
My contoller:
[HttpPost]
[Route("/jobApi/RunBD")]
public int RunBDReport([FromBody]int month, [FromBody] IEnumerable<ClientModel> clients)
{
billingDetailCycle objBillDetail = new billingDetailCycle();
if (ModelState.IsValid)
{
return objBillDetail.Run(clients.ToList(), month);
}
else
{
return 500;
}
}
ClientModel:
public class ClientModel
{
public string BlockOfBus { get; set; }
public string ClientId { get; set; }
public string Location { get; set; }
public string SuppressSsn { get; set; }
}
The request I am sending:
{"month":7,
"ClientModel":[{"blockOfBus":"XXX",
"clientId":"123456",
"location":"",
"suppressSsn":"N"}]}
This causes both parameters to be seen as null by the controller, however if I send my request like this:
[{"blockOfBus":"XXX",
"clientId":"123456",
"location":"",
"suppressSsn":"N"}]
Then the controller is able to see the list object I am sending (however it obviously returns 500 as the model is not valid)

[FromBody] can only be used once since the request body can only be read once.
Don't apply [FromBody] to more than one parameter per action method. Once the request stream is read by an input formatter, it's no longer available to be read again for binding other [FromBody] parameters.
Reference Model Binding in ASP.NET Core
Create a single model that matches the expected data.
public class DbReport {
public int month { get; set; }
public ClientModel[] ClientModel { get; set; }
}
And update the action accordingly
[HttpPost]
[Route("/jobApi/RunBD")]
public int RunBDReport([FromBody]DbReport report) {
billingDetailCycle objBillDetail = new billingDetailCycle();
if (ModelState.IsValid) {
return objBillDetail.Run(report.ClientModel.ToList(), report.month);
} else {
return 500;
}
}

There can be only one parameter modified with [FromBody] attribute. So you need to either modify your method like this :
[Route("/jobApi/RunBD/{month}")]
public int RunBDReport(int month, [FromBody] IEnumerable<ClientModel> clients)
Then make the request like this :
url :/jobApi/RunBD/7
body :
[{"blockOfBus":"XXX",
"clientId":"123456",
"location":"",
"suppressSsn":"N"}]
Or modify both your method and model like this :
public class BdPayload{
public int Month {get; set;}
public IEnumerable<ClientModel> ClientModel {get;set;}
}
[Route("/jobApi/RunBD")]
public int RunBDReport( [FromBody] BdPayload model)
and then you can use the second request's body.

Try:
{"month":7,
"clients":[{"blockOfBus":"XXX",
"clientId":"123456",
"location":"",
"suppressSsn":"N"}]}
It looks like your ClientModel enumerable is mistitled in the payload

Try changing the route to:
[Route("/jobApi/RunBD/{month}")]
public int RunBDReport([FromUri]int month, [FromBody] IEnumerable<ClientModel> clients)
The payload needs to be passed as an array, like in Jonathan's answer.

There are few simple rules that help you get through these kind of issues when trying to pass data to your Web API endpoint. These are the default rules based on which the parameter binding happens. Based on these rules, you need to be applying the attributes like [FromBody] and [FromUri]
GET method call takes both primitive and complex types as a part of the query string
POST method call takes a primitive type parameter by default in the query string and the complex type needs to be passed as a part of the request body.
PUT and PATCH follow similar default rules as that of POST.
DELETE method's default rules are inline with the GET method.
Here by primitive types, I mean types like int and complex types are the classes that we create.
You can tackle the problem that you're dealing with by applying any of the solutions that others have already mentioned -- like moving your complex type into your request body and passing the primitive type through the query string OR wrapping both the primitive and complex types into a single model and deserialize the request body to the model type (which is done as a part of the parameter binding inherently).

ASP.NET MVC 6 Core - Validation issue / bug?

I've migrated an MVC4 app to MVC6 (both .NET 4.6.1) and am hitting numerous errors with the inbuilt model validation.
I have a number of complex models that are posted to controllers, and unless I disable validation on each model under configure services, they throw unnecessary exceptions relating to properties that are irrelevant to validation, or just hang after postback without reaching the controller action.
I have added the following line to MVC Configuration for all my affected classes, but I've now got a model that requires validation, so turning it off will cause numerous code changes.
options.ModelMetadataDetailsProviders.Add(new SuppressChildValidationMetadataProvider(typeof(TestModel)));
I tried this with a test app and can replicate the issue:
Test Controller:
public IActionResult Index()
{
return View();
}
[HttpPost]
public IActionResult Index(TestModel model)
{
return View();
}
Test Model (for example)
public class TestModel
{
[Required]
public string Name { get; set; }
[Required]
[DataType(DataType.EmailAddress)]
public string Email { get; set; }
public int NameLength
{
get
{
return Name.Length;
}
}
}
Without the validation attributes, the code works fine, but is not validated (obviously).
But when this model is posted, a NullReference exception is thrown by the NameLength property, even though no code references it, the property is read only, and the property it depends on is required. This validation happens before control is returned to the controller.
I've tried disabling this functionality in MvcOptions, but it doesn't have any effect:
options.MaxValidationDepth = null;
options.AllowValidatingTopLevelNodes = false;
options.AllowShortCircuitingValidationWhenNoValidatorsArePresent = true;
I don't know if there's a setting I'm missing, but I would expect the default functionality to ignore properties without validation attributes, or am I doing something wrong?.
Thanks in advance for your help.
Further to #Henks suggestion, I've added the ValidateNever attribute to the readonly properties of one class I was having problems with, which has worked, so the postback reaches the controller now, but its still calling the properties, it just seems to ignore the result:
[ValidateNever]
public Competition PrimaryCompetition
{
get
{
return GetCompetition(true);
}
}
This still triggers a null reference exception because it relies on another property that is [Required] but is not validated first.
I'm beginning to think this is a bug rather than an error on my part.

Why this happens
I haven't seen this issue with simple types (like in some of the example code you posted), but we just had a similar issue with complex types.
From looking at the source code, this has to do with how the complex model binder works. It steps through every public property getter that is a complex type (e.g. a class) when posted regardless of whether the property was used at all. I think this may be an intentional choice by Microsoft because it is possible that the underlying properties of a complex type could be settable.
For example if your Competition class and PrimaryCompetition property on another class (called Test here) looked like this:
public class Competition
{
public string Name { get; set; }
public List<string> Roster { get; set; } = new List<string>();
}
public class Test
{
public Competition PrimaryCompetition
{
get
{
return AllCompetitions.First();
}
}
public List<Competition> AllCompetitions { get; set; } = new List<Competition>();
}
Underlying properties of PrimaryCompetition can be modified even though it has no setter:
var competition = new Competition {
Name = "Soccer"
};
competition.Roster.Add("Sara");
var test = new Test();
// This code outputs "Sara"
test.AllCompetitions.Add(competition);
Console.WriteLine(test.PrimaryCompetition.Roster[0]);
// This code outputs "Amanda"
test.PrimaryCompetition.Roster[0] = "Amanda";
Console.WriteLine(test.PrimaryCompetition.Roster[0]);
Possible solutions
Make the property a method instead:
public Competition PrimaryCompetition() => GetCompetition(true);
Make the property internal instead of public:
internal Competition PrimaryCompetition
{
get
{
return GetCompetition(true);
}
}
Add the ValidateNever and BindNever attributes to the property:
[BindNever]
[ValidateNever]
public Competition PrimaryCompetition
{
get
{
return GetCompetition(true);
}
}
We decided to go with option 1 since in Microsoft's best practices they recommend not throwing exceptions from getters Property Design.
Property getters should be simple operations and should not have any preconditions. If a getter can throw an exception, it should probably be redesigned to be a method.

WebAPI - Array of Objects not deserializing correctly on server side

In the client-side, I am using AngularJS and in the server-side I am using ASP.NET WebAPI.
I have two view models, ProductCriteriaViewModel and SimpleDisplayFieldViewModel:
public class ProductCriteriaViewModel
{
public int ID { get; set; }
public int? UserSearchID { get; set; }
public bool? Enabled { get; set; }
public SimpleDisplayFieldViewModel Property { get; set; }
public string Operator { get; set; }
public string CriteriaValue { get; set; }
}
public class SimpleDisplayFieldViewModel
{
public string Name { get; set; }
public string Value { get; set; }
public string PropertyType { get; set; }
}
In Angular, I submit a POST request to a WebAPI controller action with the following signature:
public IList<...> FindProducts(List<ProductCriteriaViewModel> criteriaVM, bool userFiltering)
{
...
}
In testing, I tried to send an array of Product Criterias, and checked Fiddler to see what the array looked like in the body of the POST request when it was being sent to the server. This is what the array looked like:
[
{"Enabled":true,
"Operator":"Less than",
"Property":
{"$id":"2",
"Name":"Copyright Year",
"Value":"Basic",
"PropertyType":null},
"CriteriaValue":"2013",
"IsNew":true},
{"Enabled":true,
"Operator":"Greater Than",
"Property":
{"$id":"2",
"Name":"Copyright Year",
"Value":"Basic",
"PropertyType":null},
"CriteriaValue":"1988",
"IsNew":true}
]
The above array has the correct values, however the result of deserialization on the server-side is incorrect. This is where it gets strange.
After the server deserializes the array and arrives in the controller action, the first element in criteriaVM is correct, all the values are set properly. However the second element is incorrect, CriteriaValue and Property are nulled out:
This issue only occurs whenever I choose the same search property for more than one criteria (i.e. Copyright < 2013 and Copyright > 1988). However, if I choose different properties (i.e. Copyright < 2013 and Price > 20), then all elements in the resulting criteriaVM are correctly initialized.
I do not understand what could be causing this issue. Why are only CriteriaValue and Property set to null in the second element of the List? Why does this issue only occur when I choose multiples of the same search properties?

Json.NET uses the keywords $id and $ref in order to preserve object references, so you are having troubles with your deserialization because your JSON has "$id" in the "Property" object. See this link for more information about object references.
In order to fix your deserialization issues, you can add the following line in the Register method of your WebApiConfig.cs class
config.Formatters.JsonFormatter.SerializerSettings.MetadataPropertyHandling = MetadataPropertyHandling.Ignore;
If your Web Api project does not include a WebApiConfig.cs class, simply add the configuration in your Global.asax:
GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.MetadataPropertyHandling = MetadataPropertyHandling.Ignore;
Now your object in the web api method should look like this:

ASP.NET MVC Conditional validation

How to use data annotations to do a conditional validation on model?
For example, lets say we have the following model (Person and Senior):
public class Person
{
[Required(ErrorMessage = "*")]
public string Name
{
get;
set;
}
public bool IsSenior
{
get;
set;
}
public Senior Senior
{
get;
set;
}
}
public class Senior
{
[Required(ErrorMessage = "*")]//this should be conditional validation, based on the "IsSenior" value
public string Description
{
get;
set;
}
}
And the following view:
<%= Html.EditorFor(m => m.Name)%>
<%= Html.ValidationMessageFor(m => m.Name)%>
<%= Html.CheckBoxFor(m => m.IsSenior)%>
<%= Html.ValidationMessageFor(m => m.IsSenior)%>
<%= Html.CheckBoxFor(m => m.Senior.Description)%>
<%= Html.ValidationMessageFor(m => m.Senior.Description)%>
I would like to be the "Senior.Description" property conditional required field based on the selection of the "IsSenior" propery (true -> required). How to implement conditional validation in ASP.NET MVC 2 with data annotations?

There's a much better way to add conditional validation rules in MVC3; have your model inherit IValidatableObject and implement the Validate method:
public class Person : IValidatableObject
{
public string Name { get; set; }
public bool IsSenior { get; set; }
public Senior Senior { get; set; }
public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
{
if (IsSenior && string.IsNullOrEmpty(Senior.Description))
yield return new ValidationResult("Description must be supplied.");
}
}
Read more at Introducing ASP.NET MVC 3 (Preview 1).

I have solved this by handling the "ModelState" dictionary, which is contained by the controller. The ModelState dictionary includes all the members that have to be validated.
Here is the solution:
If you need to implement a conditional validation based on some field (e.g. if A=true, then B is required), while maintaining property level error messaging (this is not true for the custom validators that are on object level) you can achieve this by handling "ModelState", by simply removing unwanted validations from it.
...In some class...
public bool PropertyThatRequiredAnotherFieldToBeFilled
{
get;
set;
}
[Required(ErrorMessage = "*")]
public string DepentedProperty
{
get;
set;
}
...class continues...
...In some controller action ...
if (!PropertyThatRequiredAnotherFieldToBeFilled)
{
this.ModelState.Remove("DepentedProperty");
}
...
With this we achieve conditional validation, while leaving everything else the same.
UPDATE:
This is my final implementation: I have used an interface on the model and the action attribute that validates the model which implements the said interface. Interface prescribes the Validate(ModelStateDictionary modelState) method. The attribute on action just calls the Validate(modelState) on IValidatorSomething.
I did not want to complicate this answer, so I did not mention the final implementation details (which, at the end, matter in production code).

I had the same problem yesterday but I did it in a very clean way which works for both client side and server side validation.
Condition: Based on the value of other property in the model, you want to make another property required. Here is the code
public class RequiredIfAttribute : RequiredAttribute
{
private String PropertyName { get; set; }
private Object DesiredValue { get; set; }
public RequiredIfAttribute(String propertyName, Object desiredvalue)
{
PropertyName = propertyName;
DesiredValue = desiredvalue;
}
protected override ValidationResult IsValid(object value, ValidationContext context)
{
Object instance = context.ObjectInstance;
Type type = instance.GetType();
Object proprtyvalue = type.GetProperty(PropertyName).GetValue(instance, null);
if (proprtyvalue.ToString() == DesiredValue.ToString())
{
ValidationResult result = base.IsValid(value, context);
return result;
}
return ValidationResult.Success;
}
}
Here PropertyName is the property on which you want to make your condition
DesiredValue is the particular value of the PropertyName (property) for which your other property has to be validated for required
Say you have the following
public class User
{
public UserType UserType { get; set; }
[RequiredIf("UserType", UserType.Admin, ErrorMessageResourceName = "PasswordRequired", ErrorMessageResourceType = typeof(ResourceString))]
public string Password
{
get;
set;
}
}
At last but not the least , register adapter for your attribute so that it can do client side validation (I put it in global.asax, Application_Start)
DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(RequiredIfAttribute),typeof(RequiredAttributeAdapter));

I've been using this amazing nuget that does dynamic annotations ExpressiveAnnotations
You could validate any logic you can dream of:
public string Email { get; set; }
public string Phone { get; set; }
[RequiredIf("Email != null")]
[RequiredIf("Phone != null")]
[AssertThat("AgreeToContact == true")]
public bool? AgreeToContact { get; set; }

You can disable validators conditionally by removing errors from ModelState:
ModelState["DependentProperty"].Errors.Clear();

Thanks Merritt :)
I've just updated this to MVC 3 in case anyone finds it useful: Conditional Validation in ASP.NET MVC 3.

There is now a framework that does this conditional validation (among other handy data annotation validations) out of the box:
http://foolproof.codeplex.com/
Specifically, take a look at the [RequiredIfTrue("IsSenior")] validator. You put that directly on the property you want to validate, so you get the desired behavior of the validation error being associated to the "Senior" property.
It is available as a NuGet package.

You need to validate at Person level, not on Senior level, or Senior must have a reference to its parent Person. It seems to me that you need a self validation mechanism that defines the validation on the Person and not on one of its properties. I'm not sure, but I don't think DataAnnotations supports this out of the box. What you can do create your own Attribute that derives from ValidationAttribute that can be decorated on class level and next create a custom validator that also allows those class-level validators to run.
I know Validation Application Block supports self-validation out-of the box, but VAB has a pretty steep learning curve. Nevertheless, here's an example using VAB:
[HasSelfValidation]
public class Person
{
public string Name { get; set; }
public bool IsSenior { get; set; }
public Senior Senior { get; set; }
[SelfValidation]
public void ValidateRange(ValidationResults results)
{
if (this.IsSenior && this.Senior != null &&
string.IsNullOrEmpty(this.Senior.Description))
{
results.AddResult(new ValidationResult(
"A senior description is required",
this, "", "", null));
}
}
}

I had the same problem, needed a modification of [Required] attribute - make field required in dependence of http request.The solution was similar to Dan Hunex answer, but his solution didn't work correctly (see comments). I don't use unobtrusive validation, just MicrosoftMvcValidation.js out of the box.
Here it is. Implement your custom attribute:
public class RequiredIfAttribute : RequiredAttribute
{
public RequiredIfAttribute(/*You can put here pararmeters if You need, as seen in other answers of this topic*/)
{
}
protected override ValidationResult IsValid(object value, ValidationContext context)
{
//You can put your logic here
return ValidationResult.Success;//I don't need its server-side so it always valid on server but you can do what you need
}
}
Then you need to implement your custom provider to use it as an adapter in your global.asax
public class RequreIfValidator : DataAnnotationsModelValidator <RequiredIfAttribute>
{
ControllerContext ccontext;
public RequreIfValidator(ModelMetadata metadata, ControllerContext context, RequiredIfAttribute attribute)
: base(metadata, context, attribute)
{
ccontext = context;// I need only http request
}
//override it for custom client-side validation
public override IEnumerable<ModelClientValidationRule> GetClientValidationRules()
{
//here you can customize it as you want
ModelClientValidationRule rule = new ModelClientValidationRule()
{
ErrorMessage = ErrorMessage,
//and here is what i need on client side - if you want to make field required on client side just make ValidationType "required"
ValidationType =(ccontext.HttpContext.Request["extOperation"] == "2") ? "required" : "none";
};
return new ModelClientValidationRule[] { rule };
}
}
And modify your global.asax with a line
DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(RequiredIfAttribute), typeof(RequreIfValidator));
and here it is
[RequiredIf]
public string NomenclatureId { get; set; }
The main advantage for me is that I don't have to code custom client validator as in case of unobtrusive validation. it works just as [Required], but only in cases that you want.

Check out Simon Ince's Conditional Validation in MVC.
I am working through his example project right now.

Typical usage for conditional removal of error from Model State:
Make conditional first part of controller action
Perform logic to remove error from ModelState
Do the rest of the existing logic (typically Model State validation, then everything else)
Example:
public ActionResult MyAction(MyViewModel vm)
{
// perform conditional test
// if true, then remove from ModelState (e.g. ModelState.Remove("MyKey")
// Do typical model state validation, inside following if:
// if (!ModelState.IsValid)
// Do rest of logic (e.g. fetching, saving
In your example, keep everything as is and add the logic suggested to your Controller's Action. I'm assuming your ViewModel passed to the controller action has the Person and Senior Person objects with data populated in them from the UI.

I'm using MVC 5 but you could try something like this:
public DateTime JobStart { get; set; }
[AssertThat("StartDate >= JobStart", ErrorMessage = "Time Manager may not begin before job start date")]
[DisplayName("Start Date")]
[Required]
public DateTime? StartDate { get; set; }
In your case you would say something like "IsSenior == true".
Then you just need to check the validation on your post action.