Validating view data before its set into the model - validation

Question

My model object superficially is quite simple I don't think its worth describing my model, but a good analogy would be a SQL connection string, its just a string, but the rules for constructing it are quite complex, requiring a number of conditional UI elements depending on the DB, and other options.
Some of the data I have in the view can not be written to back to the Model if its invalid (imagine the database name is a quoted string, if a quote character is entered by the user, this can’t be written into the connection string without making the connection string unreadable).
The blazor validation API requires a model object to work from, so how do I create a validator for my blazor control that reports the errors against the invalid view fields. In this case the model is just the ConnectionString string field, and although I could write a custom validator for that, the data in it may not represent the data in the view, as the view can't always be written to the model.
UPDATED With Code
The following code shows the concept, I can't find a way for the validation rules in ConnectionStringViewModel to be run within the DatabaseInfoEditor.
class DatabaseInfoModel
{
[MaxLength(10)]
public string Name {get;set;}
[ValidateComplexType] // used to cause validation of child objects - but there is no child object to validate, what we want to validate is the ConnectionStringViewModel
public string ConnectionString {get;set;}
}
DatabaseInfoEditor.razor
<EditForm Model="MyDatabaseInfoModel">
<ObjectGraphDataAnnotationsValidator />
Name:<TextEditor #bind-Text="MyDatabaseInfoModel.Name"/>
<ConnectionStringEditor ConnectionString="MyDatabaseInfoModel.ConnectionString "/>
</EditForm>
ConnectionStringEditor.razor
Database:<TextEditor #bind-Text="MyConnectionStringViewModel.Database"/>
Username:<TextEditor #bind-Text="MyConnectionStringViewModel.Username"/>
#code
{
[Parameter]
public string ConnectionString {get;set;}
ConnectionStringViewModel MyConnectionStringViewModel;
override OnParameterSet()
{
base.OnParameterSet();
MyConnectionStringViewModel = PickApartConnectionString(ConnectionString);
}
class ConnectionStringViewModel
{
[MaxLength(10)]
public string Database {get;set;}
[MaxLength(10)]
public string Username {get;set;}
}
}