ASP.NET MVC 5 and AngularJs (1.8.2) – Solving the Mysterious Data Update Issue

Are you tired of dealing with unexpected data updates in your ASP.NET MVC 5 and AngularJs application? You’re not alone! In this article, we’ll dive into a peculiar issue where a certain field from one data is being updated by another data that has a different Id. Buckle up, folks, as we embark on a troubleshooting adventure to resolve this enigmatic problem!

Understanding the Problem

Before we dive into the solution, let’s first understand the issue at hand. Imagine you have two entities: `Order` and `Product`. Each order has a unique `Id` and a `ProductId` that references the corresponding product. In your AngularJs application, you’re displaying a list of orders along with their respective product details.

// Order entity
public class Order
{
    public int Id { get; set; }
    public int ProductId { get; set; }
    public string OrderName { get; set; }
    public decimal Total { get; set; }
}

// Product entity
public class Product
{
    public int Id { get; set; }
    public string ProductName { get; set; }
    public decimal Price { get; set; }
}

Now, let’s say you have an update functionality that allows users to modify the `OrderName` and `Total` fields of an order. However, when you update an order, you notice that the `ProductName` and `Price` fields of a different order (with a different `Id`) are being updated as well. This is not only confusing but also incorrect!

Debugging the Issue

To troubleshoot this issue, let’s first examine the AngularJs code that’s responsible for updating the order data.

// AngularJs controller
app.controller('OrderController', function ($scope, OrderService) {
    $scope.updateOrder = function (order) {
        OrderService.updateOrder(order)
            .then(function (response) {
                // Update the order list
                $scope.orders = response.data;
            }, function (error) {
                console.log(error);
            });
    };
});

// AngularJs service
app.factory('OrderService', function ($http) {
    return {
        updateOrder: function (order) {
            return $http.put('/api/orders/' + order.Id, order);
        }
    };
});

At first glance, the code looks fine. However, let’s take a closer look at the `updateOrder` function in the `OrderService`. Notice how we’re sending the entire `order` object in the PUT request? This might be the culprit behind the mysterious data update issue.

The Culprit: AngularJs’ $httpPUT Method

The issue lies in the way AngularJs’ `$http` service handles PUT requests. When you send a JSON object in a PUT request, AngularJs will automatically convert it into a URL-encoded string using the `$.param()` method. This method includes all properties of the object, regardless of whether they’re part of the original data or not.

In our case, when we send the `order` object in the PUT request, AngularJs includes all properties, including the `ProductName` and `Price` fields that are being updated incorrectly. This is because these fields are part of the `order` object, even though they’re not supposed to be updated.

The Solution: Using ASP.NET MVC 5’s JsonConverter

To resolve this issue, we need to ensure that only the intended fields are updated in the PUT request. One way to achieve this is by using ASP.NET MVC 5’s `JsonConverter` to customize the serialization of our data.

// ASP.NET MVC 5 controller
public class OrdersController : Controller
{
    [HttpPut]
    public IHttpActionResult UpdateOrder(int id, [FromBody]Order order)
    {
        // Use JsonConverter to serialize only the intended fields
        var serializerSettings = new JsonSerializerSettings();
        serializerSettings.ContractResolver = new OnlyRequiredPropertiesResolver();
        var json = JsonConvert.SerializeObject(order, serializerSettings);

        // Update the order data
        // ...

        return Ok();
    }
}

// Custom JsonConverter
public class OnlyRequiredPropertiesResolver : DefaultContractResolver
{
    protected override IList CreateProperties(Type type, MemberSerialization memberSerialization)
    {
        IList properties = base.CreateProperties(type, memberSerialization);

        // Filter out properties that are not required
        return properties.Where(p => p.PropertyType.IsPrimitive || p.PropertyType.IsValueType || p.PropertyType.Name.StartsWith("String")).ToList();
    }
}

In the above code, we’re using the `JsonSerializerSettings` to specify a custom `ContractResolver`. This resolver, `OnlyRequiredPropertiesResolver`, filters out properties that are not required for updating the order data.

AngularJs Modifications

Now that we’ve customized the serialization on the server-side, let’s modify our AngularJs code to send only the required fields in the PUT request.

// AngularJs service
app.factory('OrderService', function ($http) {
    return {
        updateOrder: function (order) {
            // Create a new object with only the required fields
            var updateOrder = {
                Id: order.Id,
                OrderName: order.OrderName,
                Total: order.Total
            };

            return $http.put('/api/orders/' + order.Id, updateOrder);
        }
    };
});

By creating a new object with only the required fields, we ensure that the PUT request sends only the intended data to the server.

Conclusion

In this article, we’ve tackled a peculiar issue where a certain field from one data was being updated by another data with a different Id. By understanding the problem, debugging the issue, and applying a custom solution using ASP.NET MVC 5’s `JsonConverter` and modifying our AngularJs code, we’ve successfully resolved the mysterious data update issue.

Remember, when working with complex data structures and APIs, it’s essential to pay attention to the subtleties of data serialization and deserialization. By doing so, you’ll avoid unexpected data updates and ensure the integrity of your application’s data.

Takeaway

• Use a custom `JsonConverter` to control data serialization on the server-side.
• Send only the required fields in the PUT request from the AngularJs side.
• Debug your code thoroughly to identify unexpected data updates.

With these lessons learned, you’ll be better equipped to tackle similar issues in your ASP.NET MVC 5 and AngularJs applications. Happy coding!

Keyword	Description
ASP.NET MVC 5	A web application framework developed by Microsoft
AngularJs
JsonConverter	A .NET library for converting JSON data to .NET objects and vice versa
$httpPUT	An AngularJs method for sending a PUT request to a server

By following the instructions outlined in this article, you should be able to resolve the issue of a certain field from one data being updated by another data with a different Id in your ASP.NET MVC 5 and AngularJs application.

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