Assigning to an array field through reflection in c#

Question

I use reflection to get FieldInfos in a class and assign to them with FieldInfo.SetValue. It works fine when i assign primitive types (i use Convert.ChangeType to convert from object to type) but doesn't work if the field is an array. It works if i use Array.Cast but the type is only known at runtime so i cant cast. I saw lots of topics on this but none of them worked so far.

I get this exception:

ArgumentException: Object type System.Object[] cannot be converted to target type: System.Single[]

I know why it happens i just can't find a way to convert the data. Any ideas?

EDIT: relevant code:

 public static object Deserialize (string path){
        string[] lines = File.ReadAllLines(path);
        ConstructorInfo ci = type.GetConstructor(Type.EmptyTypes);
        object newObj = ci.Invoke(new object[] {});
        Type type = Type.GetType(lines[0], true);
        FieldInfo[] fields = type.GetFields(BindingFlags.Public);



        for (int i = 1; i < lines.Length; i++){
            FieldInfo thisField = currentType.GetField(lines[i]);
                if (thisField != null) {
                    if (line != "") {
                        if (fieldType == typeof(string)) {
                            thisField.SetValue(currentObject, line);
                            thisField = null;
                        }
                        else if (fieldType.IsPrimitive) {
                            val = Convert.ChangeType(line, fieldType);
                            thisField.SetValue(currentObject, val);
                            thisField = null;
                        }
                        else if (fieldType.IsArray){
                            string[] values = ReadUntil(']');
                            //ReadUntil just returns the values as string[] as read from text file
                            object[] newValues = Convert.ChangeType(values, fieldType);

                            thisField.SetValue(newObj, newValues);
                        }
                    }
                }
            }
        }
        return newObj;
    }

checkout this possible duplicate posting - http://stackoverflow.com/questions/13270183/type-conversion-issue-when-setting-property-through-reflection — MethodMan, Nov 28 '15 at 20:08
thanks but as i've said: i can assign primitives just fine - the only problem is with arrays — Jed, Nov 28 '15 at 20:27

Ivan Stoev · Accepted Answer · 2015-11-28T22:27:29.933

You can use something like this

else if (fieldType.IsArray)
{
    string[] values = ReadUntil(']');
    var elementType = fieldType.GetElementType();
    if (elementType == typeof(string))
        thisField.SetValue(newObj, values);
    else
    {
        var actualValues = Array.CreateInstance(elementType, values.Length);
        for (int i = 0; i < values.Length; i++)
            actualValues.SetValue(Convert.ChangeType(values[i], elementType), i);
        thisField.SetValue(newObj, actualValues);
    }
}

Type.GetElementType method is used to retrieve the type of the array elements, then Array.CreateInstance method to create an array of the desired type, and finally Array.SetValue method to populate the new array elements with the converted values.

Thanks! That was exactly what i was looking for :) – Jed Nov 28 '15 at 22:30 — Jed, Nov 28 '15 at 22:30

Assigning to an array field through reflection in c#

1 Answers1