Simple C# MVC ModelState Error List

There are situations where you need to add an error to the state of the model. 

Add Error To Model
In these situations it is as easy as

ModelState.AddModelError("EmailAddress","Duplicate email.");

Model Errors
Then you may want to inspect the ModelState to determine if you have any errors before continuing processing. 

If (ModelState.IsValid == true)  { //Perform actions}

Specific Model Error
But what if you just want to inspect a particular error to perform another action?

int errorCount = ModelState["EmailAddr"].Errors;

List of Model Errors
You can also get a list of errors from the model

List<ModelError> modelErrorList = ModelState.Keys.SelectMany(x => this.ModelState[x].Errors).ToList();