C# copy list of objects without reference

Question

1.00/5 (1 vote)

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Hello,

My problem is about the copy of object without reference.

What I have tried:

I try to copy a list of object like this :

C#

List<MyObject> myNewList = new List<MyObject>(myOldList);

The problem is that my new list reference the older list.

Here is my object "MyObject" :

C#

/// <summary>
    /// Model to represent a trip.
    /// </summary>
    [Serializable]
    public class TripModel : BaseModel, IEquatable<TripModel>, IComparableModel
    {
        /// <summary>
        /// Initialises a new instance of the <see cref="TripModel" /> class.
        /// </summary>
        public TripModel()
        {
            this.PropertyBags = new SimpleSerializableDictionary<string, string>();
            this.TripPlans = new SimpleSerializableDictionary<TripEnums.TripPlanType, TripPlanModel>();
            this.PreviewMode = GeneralEnums.PreviewMode.Unchanged;
        }

        /// <summary>
        /// Gets or sets the direction of the trip.
        /// </summary>
        public TripEnums.TripDirection Direction
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets the instantiation mode of the trip.
        /// </summary>
        public TripEnums.TripInstantiationMode InstantiationMode
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets the number of the next trip.
        /// </summary>
        public int NextTripNumber
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets the number of the previous trip.
        /// </summary>
        public int PreviousTripNumber
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets the property bags of the trip.
        /// </summary>
        public SimpleSerializableDictionary<string, string> PropertyBags
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets the service ID of the trip.
        /// </summary>
        public string ServiceId
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets the state of the trip.
        /// </summary>
        public TripEnums.TripState State
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets the ID of the trip.
        /// </summary>
        public string TripId
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets the number of the trip.
        /// </summary>
        public int TripNumber
        {
            get;
            set;
        }

        public GeneralEnums.PreviewMode PreviewMode
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets the trip plans of the trip.
        /// </summary>
        public SimpleSerializableDictionary<TripEnums.TripPlanType, TripPlanModel> TripPlans
        {
            get;
            set;
        }

        /// <summary>
        /// Indicates whether the current object is equal to another object of the same type.
        /// </summary>
        /// <param name="other">An object to compare with this object.</param>
        /// <returns>Returns true if the two objects are equal false otherwise.</returns>
        public bool Equals(TripModel other)
        {
            if (other == null)
            {
                return false;
            }

            return this.TripNumber == other.TripNumber
                   && this.ServiceId == other.ServiceId
                   && this.TripId == other.TripId
                   && this.Direction == other.Direction
                   && this.State == other.State
                   && this.InstantiationMode == other.InstantiationMode
                   && this.PreviousTripNumber == other.PreviousTripNumber
                   && this.NextTripNumber == other.NextTripNumber
                   && object.Equals(this.PropertyBags, other.PropertyBags)
                   && object.Equals(this.TripPlans, other.TripPlans);
        }

        /// <summary>
        /// Determines whether the specified System.Object is equal to the current System.Object.
        /// </summary>
        /// <param name="obj">The System.Object to compare with the current System.Object.</param>
        /// <returns>Returns true if the two objects are equal false otherwise.</returns>
        public override bool Equals(object obj)
        {
            return obj != null && this.Equals(obj as TripModel);
        }

        /// <summary>
        /// Serves as a hash function for <see cref="TripModel" />.
        /// </summary>
        /// <returns>A hash code for the current <see cref="TripModel" />.</returns>
        public override int GetHashCode()
        {
            return
                new
                {
                    this.TripNumber,
                    this.ServiceId,
                    this.TripId,
                    this.Direction,
                    this.State,
                    this.InstantiationMode,
                    this.PreviousTripNumber,
                    this.NextTripNumber,
                    this.PropertyBags,
                    this.TripPlans
                }.GetHashCode();
        }

        /// <summary>
        /// Adds an information to the object indicating 
        /// if the object has been updated, deleted, inserted
        /// or unchanged.
        /// </summary>
        /// <param name="previewMode"></param>
        public void AddModification(GeneralEnums.PreviewMode previewMode)
        {
            this.PreviewMode = previewMode;
        }


    }

Thank you for your help...

Posted 11-Apr-18 4:40am

yaluobth

Updated 11-Feb-22 20:41pm

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Comments

BillWoodruff 11-Apr-18 14:30pm

Looking at your code: why are you using PropertyBags when what you are working with are really simple POCO classes ?

3 solutions

Solution 4

Make it a structure instead of a class or Create a clone method within your class and Return this.MemeberwiseClone;

Posted 11-Feb-22 20:41pm

David Rizzo

Comments

Richard Deeming 14-Feb-22 11:09am

A structure wouldn't be able to inherit from the BaseModel class. And the copy constructor was already suggested four years ago in solution 2.

If you're going to post a new answer to such an old question, make sure you're adding something new to the discussion.

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F-ES Sitecore · Accepted Answer · 2018-04-11T04:54:00

Solution 1

You probably want to clone your original list instead

How do I clone a generic list in C#? - Stack Overflow[^]

Posted 11-Apr-18 4:54am

F-ES Sitecore

Comments

yaluobth 11-Apr-18 11:27am

It works... Thank you very much

#realJSOP · Accepted Answer · 2018-04-11T04:56:00

You could create a copy constructor in your object that accepts an object of the same type:

public MyObject(MyObject obj)
{
    this.Property1 = obj.Property1;
    this.Property2 = obj.Property2;
    ...
}

And then do this when you want to copy it:

List<MyObject> list2 = list1.ConvertAll(x => new MyObject(x));

OR inherit ICloneable, and

C#

public class MyObject : ICloneable<MyObject>
{
    public MyObject Clone()
    {
        return new MyObject{ /* set properties */ };
    }
}

And do this:

List<MyObject> list2 = list1.ConvertAll(x => x.Clone());

OR

You could serialize the existing objects into a stream and deserialize them back into a new list of objects.

C# copy list of objects without reference

3 solutions

Solution 1

Solution 2

Solution 4

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