When it comes to users entering data, it's important to always validate the integrity before storing the information. The earlier you can do that the better, so why validate server-side when you can validate client-side before submitting the postback?
You'll need to follow the steps I blogged about here to configure your single page app (SPA) setup to run with ReactJS + Redux + C# ASP.Net Core.
Assuming you've setup your local repository as per the aforementioned blog, the first thing to code is a component to hold our dynamic label. Everything in this example will be based on Bootstrap 4. Validation icons are cool, so let's add one of those which can be dynamically change as and when necessary.
Next is the label component itself, which will need to import our validation icon to be used as and when necessary.
Now that our label component is coded, let's add a further component to hold our validation error messages.
Next we need to construct an input field component which imports our label and field error components.
Now that our input field component is constructed, we need a button component which will remain disabled until all input components are valid.
We now need a data model for our server-side code, written in C# .Net Core.
Next, some more server-side code (our api controller and a static list to store the data in C# ASP.Net Core).
Now for the part where Redux comes in to facilitate our connection between the client-side and the server-side. We'll expose a "submitForm" function within our action creators, to dispatch and receive our request and response.
...accompanied by some simple reducer statements.
Next we need to code the client-side validation, starting with some constants in our SignUpForm component -
Following this, we'll need a constructor and some properties to manipulate when the user interacts with the form.
Now we can render our form component, using the input field component we coded at the beginning.
You'll note that each input field has a function attached to its onChange method, specifically for handling user input -
Now to validate the inputs with a glorious switch statement, depending on the field name.
Let's run our build and see what we've got -
...and to test the validation as we type in our name -
Followed by our email address, which validates differently based on our switch statement.
Here we can clearly see the valid fields vs. the invalid fields -
Eventually our end result enables our form submission button -
Clicking submit now shows us our received response from our C# ASP.Net Core api.
Download Github Code Sample
Feel free to DOWNLOAD the sample code of the aforementioned implementation from my Github account.