c# - Expression.Convert: Object of type 'System.Int64' cannot be converted to type 'System.Int32' -

i asked question yesterday here reading properties anonymous object , writing them private fields of class. problem solved. here short story:

i have data in json format. deserialize them expandoobject, , pass them idictionary<string, object> method. works fine, except int32 properties. seems change int64, where? don't know.

here method again:

    private func<idictionary<string, object>, dynamic> makecreator(         type type, expression ctor,         ienumerable<propertytofieldmapper> maps) {          var list = new list<expression>();         var vlist = new list<parameterexpression>();          // creating new target         var targetvariable = expression.variable(type, "targetvariable");         vlist.add(targetvariable);         list.add(expression.assign(targetvariable, expression.convert(ctor, type)));          // accessing source         var sourcetype = typeof(idictionary<string, object>);         var sourceparameter = expression.parameter(sourcetype, "sourceparameter");          // calling source containskey(string) method         var containskeymethodinfo = sourcetype.getmethod("containskey", new[] { typeof(string) });          var accesssourceindexerprop = sourcetype.getproperty("item");         var accesssourceindexerinfo = accesssourceindexerprop.getgetmethod();          // itrate on writers , add call block         var containskeymethodargument = expression.variable(typeof(string), "containskeymethodargument");         vlist.add(containskeymethodargument);         foreach (var map in maps) {             list.add(expression.assign(containskeymethodargument, expression.constant(map.property.name)));             var containskeymethodcall = expression.call(sourceparameter, containskeymethodinfo,                                                         new expression[] { containskeymethodargument });              // creating writer             var sourcevalue = expression.call(sourceparameter, accesssourceindexerinfo,                                               new expression[] { containskeymethodargument });             var setterinfo = map.field.gettype().getmethod("setvalue", new[] { typeof(object), typeof(object) });             var settercall = expression.call(expression.constant(map.field), setterinfo,                 new expression[] {                                      expression.convert(targetvariable, typeof(object)),                                      expression.convert(sourcevalue, typeof(object))                                  });             console.writeline(expression.lambda(settercall));             list.add(expression.ifthen(containskeymethodcall, settercall));         }         list.add(targetvariable);          var block = expression.block(vlist, list);          var lambda = expression.lambda<func<idictionary<string, object>, dynamic>>(             block, new[] { sourceparameter }             );          return lambda.compile();     } 

if have this

public class person {     public int age { get; set; }     public string name { get; set; } } 

class, , use object

var data = new { name = "amiry", age = 20 }; 

to initialize instance of person using above method, error occurs:

object of type 'system.int64' cannot converted type 'system.int32'.

but if change age property to:

public long age { get; set; } 

every thing looks fine , method works perfectly. confused why happens. have idea?

so input dictionary contains long (based on discussion in comments).

the easiest fix add convert.changetype before setvalue.
(passing in sourcevalue , constant(map.field.fieldtype))
however, may have unintended consequence of allowing string -> int conversion.

alternative add own converttype method, decide how types converted.