Executing linq lamda expression as parameter in System.Reflection Invoke Method calling

Question

I'm trying to execute My GetSingleAsync method which comes with system reflection. But ı need to execute linq query when I'm invoking this method, in my researches ı mostly saw just single parameters,but ı need to execute linq expression in this method call.

Here is what I'm trying to get when ı execute:

var data = await repository.GetSingleAsync(record => record.date == StartDate.ToString("yyyy-MM-dd"));

Here is my current code try, i need to execute record => record.date == StartDate.ToString("yyyy-MM-dd") linq in question mark part:

dynamic repository = Activator.CreateInstance(RepositoryType);
 
MethodInfo GetSingleAsync = RepositoryType.GetMethod("GetSingleAsync");

var model = GetSingleAsync.Invoke(repository, ??);      //need help in question mark?

Answer 1

Basically you need to look at the parameters of GetSingleAsync. Assuming the parameter needs to be of type Func<T,bool> then you need:

Func<T,bool> predicate = rec => rec.Property == someValue;

Your parameter is then

var model = GetSingleAsync.Invoke(repository, new []{ predicate });

Update: If you do not want to depend on some Type T you can construct your predicate using Expression API:

    public static object SomePredicate(Type recordType, string propertyName, Expression comparisonValue) {
            var parameterExpression = Expression.Parameter(recordType);
            var propertyExpression = Expression.PropertyOrField(parameterExpression, propertyName);
            var lambdaExpression = Expression.Lambda(Expression.Equal(propertyExpression, comparisonValue), parameterExpression);
            return lambdaExpression.Compile();
        }

You can then construct your predicates like so (if you have a type Repository with integer Property Record):

var somePredicate = SomePredicate(typeof(Repository), nameof(Repository.Record), Expression.Constant(5));