Perform a shortest copy through the attribute and perform a shortest copy on the attribute.

Perform a shortest copy through the attribute and perform a shortest copy on the attribute.

In the past two days, I have read a code to be handed over by a departing colleague. The method of copying a copy is quite good. I will record it here.

I. Method body

Is a static method CopyHelper, which contains the following three parts

1. Add an extension method to the PropertyInfo [] type to check whether fields of the same type and name exist.

/// <Summary> // PropertyInfo [] extension method, obtain attributes by name /// </summary> /// <param name = "P"> </param> /// <param name = "pro"> </param >/// <returns> </returns> private static PropertyInfo GetPropertyByName (this PropertyInfo [] P, propertyInfo pro) {if (P = null) throw new NullReferenceException ("the parameter PropertyInfo [] of the GetPropertyByName () method in the CopyHelper class is Null"); var item = P. toList (). find (x => x. name. equals (pro. name) & (pro. propertyType. isSubclassOf (x. propertyType) | pro. propertyType. fullName. equals (x. propertyType. fullName); return item ;}

2. The shortest object method, that is, the SetValue method is used to assign values if it is not empty and can be written based on the above method.

/// <Summary> /// shallow copy /// </summary> /// <typeparam name = "T"> </typeparam> /// <param name = "vo"> original VO </param> /// <param name = "viewModel"> vo under VM </param> /// <returns> </returns> private static T O2M <T> (object vo, T viewModel) {// obtains the attribute set PropertyInfo [] VmPInfos = viewmodel. getType (). getProperties (); // obtain the attribute set of the original vo PropertyInfo [] VoPInfos = vo. getType (). getProperties (); for (int I = 0; I <VoPI Nfos. length; I ++) {// find the var pro = VmPInfos attribute corresponding to VO from the VM. getPropertyByName (VoPInfos [I]); // if it is not empty and can be written, assign if (pro! = Null & pro. canWrite) pro. setValue (viewModel, VoPInfos [I]. getValue (vo, null), null);} return viewModel;} private static T O2M <T> (object vo) where T: new () {if (vo = null) return default (T); T viewModel = new T (); return O2M <T> (vo, viewModel );}

3. expose an extended Copy method to the outside and run the call

/// <Summary> /// assign values for attributes with the same field name and type (used for conversion between ViewModel and Vo) /// </summary> /// <typeparam name = "T"> </typeparam> /// <param name = "vo"> </param> /// <returns> </returns> // <remarks> note that the value is a shortest copy, the Model will re-create new () </remarks> public static T CopyTo <T> (this object vo) where T: new () {return O2M <T> (vo );} /// <summary> /// assign values for attributes with the same field name and type (used for conversion between ViewModel and Vo) /// </summary> /// <typeparam name = "T"> </typeparam> /// <Param name = "vo"> </param> /// <returns> </returns> /// <remarks> note that the value is a shortest copy, model will re-create new () </remarks> public static bool CopyTo <T> (this object vo, T model) where T: new () {if (model = null) model = new T (); return O2M <T> (vo, model )! = Null ;}

Ii. Test

1. Create two entity classes, HumanVo and StudentVo.

public class HumanVo    {        private string _name;        private int _age;        private bool _sex;        public string Name        {            get            {                return _name;            }            set            {                _name = value;            }        }        public int Age        {            get            {                return _age;            }            set            {                _age = value;            }        }        public bool Sex        {            get            {                return _sex;            }            set            {                _sex = value;            }        }    }

public class StudentVo    {        private string _name;        private int _age;        private bool _sex;        private string _class;        private string _school;        public string Name        {            get            {                return _name;            }            set            {                _name = value;            }        }        public int Age        {            get            {                return _age;            }            set            {                _age = value;            }        }        public bool Sex        {            get            {                return _sex;            }            set            {                _sex = value;            }        }        public string Class        {            get            {                return _class;            }            set            {                _class = value;            }        }        public string School        {            get            {                return _school;            }            set            {                _school = value;            }        }    }

2. assign a value to HumanVo

Private void AddInfo () {HumanVo. Name = "Li Lei"; HumanVo. Age = 16; HumanVo. Sex = true ;}

3. Call the CopyTo Method

HumanVo.CopyTo(StudentVo);

4. view results

Before calling a method, track the code and view the values of the two VO

After calling the method, view the value of StudentVO