Get Data Annotations attributes from model

Question

I want to create custom client-side validator, but I want define validation rules via Data Annotations attributes at business logic layer. How can I access model validation

Answer 1

As commented above - I believe T4 might be worth a shot here. A huge benefit is that it's not executed at runtime (though it can, if that's your requirement) and you can avoid all possible issues with runtime file generation. Hopefully a sufficient starting point:

<#@ template language="C#" debug="True" hostspecific="true" #>
<#@ output extension="js" #>
<#@ assembly name="System.Core" #>
<#@ assembly name="EnvDTE" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="EnvDTE" #>
<#
    var serviceProvider = Host as IServiceProvider;
    if (serviceProvider == null)
    {
        throw new InvalidOperationException("Host is not IServiceProvider");
    }

    var dte = serviceProvider.GetService(typeof(DTE)) as DTE;
    if (dte == null)
    {
        throw new InvalidOperationException("Unable to resolve DTE");
    }

    var project = dte.Solution.Projects
                              .OfType()
                              .Single(p => p.Name == "ConsoleApplication2");

    var model = project.CodeModel
                       .CodeTypeFromFullName("MyApp.LoginModel")
                   as CodeClass;
    //might want to have a list / find all items matching some rule

#>
var <#= Char.ToLowerInvariant(model.Name[0])
        + model.Name.Remove(0, 1).Replace("Model", "ViewModel") #>= {
<#
    foreach (var property in model.Members.OfType())
    {
        var minLength = property.Attributes
                                    .OfType()
                                    .FirstOrDefault(a => a.Name == "MinLength");
        var required = property.Attributes
                               .OfType()
                               .FirstOrDefault(a => a.Name == "Required");

        var koAttributes = new List();
        if (minLength != null)
            koAttributes.Add("minLength: " + minLength.Value);
        if (required != null)
            koAttributes.Add("required: true");
#>
    <#= property.Name #>: ko.observable().extend({<#=
String.Join(", ", koAttributes) #>}),
<#
    }
#>
}