public void ParameterReplaceVisitorTest()
{
var p1 = Expression.Parameter(typeof(int));
var param = new Builder.ParameterReplaceVisitor(p1, p1);
Expression <Func <int, object> > p = (a) => null;
param.Visit(p);
param.Visit(p1);
Assert.AreNotEqual(param, null);
}
public static Expression <Func <T, object> > CombineSelectorsToNewObject <T>(List <FieldDefinition <T> > selectors, Type createdType)
{
var param = Expression.Parameter(typeof(T), "x");
var arguments = new List <Expression>();
foreach (var selector in selectors)
{
var replace = new ParameterReplaceVisitor(selector.Selector.Parameters[0], param);
var fieldName = SanitizeCSharpIdentifier(selector.Name);
var property = createdType.GetField(fieldName);
if (property == null)
{
throw new ApplicationException($"Could not find field {fieldName} for type {createdType}.");
}
var replacedParamExpression = replace.Visit(selector.Selector.Body);
if (replacedParamExpression == null)
{
throw new ApplicationException($"Could Visit and Convert expression: {selector.Selector}");
}
replacedParamExpression = Expression.Convert(replacedParamExpression, GetNullableType(selector.Type));
arguments.Add(replacedParamExpression);
}
var ctor = createdType.GetConstructor(selectors.Select(a => a.Type).ToArray());
if (ctor == null)
{
throw new ApplicationException(
$"Could not get ctor for created type: {createdType}, with args: {string.Join<Type>(",", selectors.Select(a => a.Type).ToArray())}");
}
var ctorExpr = Expression.New(ctor, arguments.ToArray());
return(Expression.Lambda <Func <T, object> >(ctorExpr, param));
}