public static IEnumerable <ParameterExpression> OfType <T>(Expression expression)
{
var finder =
new TypedParameterExpressionFinder(typeof(T));
_ = finder.Visit(expression);
return
(finder.FoundParameters);
}
private static void ResolveLinks <T>(
T obj,
WrapPolicy <T> policy,
Resource resource,
IUrlHelper urlHelper)
{
if (urlHelper == null)
{
return;
}
var applicableRules =
policy
.LinkingRules
.Where(r => r.AddPredicate(obj));
foreach (var rule in applicableRules)
{
var methodExpression =
rule.MethodCall.Body as MethodCallExpression
?? throw new ApplicationException($"Only MethodCallExpression is supported. Given is: '{rule.MethodCall.Body.GetType()}'");
var url =
Uri.UnescapeDataString(
urlHelper.Action(EvaluateActionContext()));
resource.Link(
new NamedLink(
rule.Name,
new Link(url)));
UrlActionContext EvaluateActionContext()
{
return
(new UrlActionContext()
{
Protocol =
urlHelper
.ActionContext
.HttpContext
.Request
.Scheme,
Host =
urlHelper
.ActionContext
.HttpContext
.Request
.Host
.Host,
Controller =
rule.ControllerName,
Action =
methodExpression.Method.Name,
Values =
EvaluateValues(),
});
}
IDictionary <string, object> EvaluateValues()
{
var values =
new Dictionary <string, object>();
foreach (var argument in GetMethodCallArguments())
{
var paramT =
TypedParameterExpressionFinder
.OfType <T>(argument.value)
.SingleOrDefault();
var value =
paramT == null
? Expression
.Lambda(argument.value)
.Compile()
.DynamicInvoke()
: Expression
.Lambda(argument.value, paramT)
.Compile()
.DynamicInvoke(obj);
values.Add(
argument.parameter.Name,
value);
}
foreach (var(name, value) in rule.QueryParameters)
{
values[name] = value;
}
foreach (var(name, value) in rule.GetQueryParametersCallback(obj))
{
values[name] = value;
}
return
(values);
}
IEnumerable <(ParameterInfo parameter, Expression value)> GetMethodCallArguments()
=> methodExpression
.Method
.GetParameters()
.Zip(
methodExpression.Arguments,
(parameter, argument) => (parameter, argument));
}
}
