Comparer les propriétés de deux objets pour trouver des différences?

J'ai deux objets du même type et je veux parcourir les propriétés publiques de chacun d'eux et alerter l'utilisateur sur les propriétés qui ne correspondent pas.

Est-il possible de faire cela sans connaître les propriétés que contient l'objet?

Oui, avec réflexion - en supposant que chaque type de propriété est Equalscorrectement implémenté . Une alternative serait d'utiliser ReflectiveEqualsrécursivement pour tous sauf certains types connus, mais cela devient délicat.

public bool ReflectiveEquals(object first, object second)
{
    if (first == null && second == null)
    {
        return true;
    }
    if (first == null || second == null)
    {
        return false;
    }
    Type firstType = first.GetType();
    if (second.GetType() != firstType)
    {
        return false; // Or throw an exception
    }
    // This will only use public properties. Is that enough?
    foreach (PropertyInfo propertyInfo in firstType.GetProperties())
    {
        if (propertyInfo.CanRead)
        {
            object firstValue = propertyInfo.GetValue(first, null);
            object secondValue = propertyInfo.GetValue(second, null);
            if (!object.Equals(firstValue, secondValue))
            {
                return false;
            }
        }
    }
    return true;
}

Bien sûr, vous pouvez avec réflexion. Voici le code pour récupérer les propriétés d'un type donné.

var info = typeof(SomeType).GetProperties();

Si vous pouvez donner plus d'informations sur ce que vous comparez sur les propriétés, nous pouvons rassembler un algorithme de base différent. Ce code pour l'instance diffère sur les noms

public bool AreDifferent(Type t1, Type t2) {
  var list1 = t1.GetProperties().OrderBy(x => x.Name).Select(x => x.Name);
  var list2 = t2.GetProperties().OrderBy(x => x.Name).Select(x => x.Name);
  return list1.SequenceEqual(list2);
}

Je sais que c'est probablement exagéré, mais voici ma classe ObjectComparer que j'utilise dans ce but précis:

/// <summary>
/// Utility class for comparing objects.
/// </summary>
public static class ObjectComparer
{
    /// <summary>
    /// Compares the public properties of any 2 objects and determines if the properties of each
    /// all contain the same value.
    /// <para> 
    /// In cases where object1 and object2 are of different Types (both being derived from Type T) 
    /// we will cast both objects down to the base Type T to ensure the property comparison is only 
    /// completed on COMMON properties.
    /// (ex. Type T is Foo, object1 is GoodFoo and object2 is BadFoo -- both being inherited from Foo --
    /// both objects will be cast to Foo for comparison)
    /// </para>
    /// </summary>
    /// <typeparam name="T">Any class with public properties.</typeparam>
    /// <param name="object1">Object to compare to object2.</param>
    /// <param name="object2">Object to compare to object1.</param>
    /// <param name="propertyInfoList">A List of <see cref="PropertyInfo"/> objects that contain data on the properties
    /// from object1 that are not equal to the corresponding properties of object2.</param>
    /// <returns>A boolean value indicating whether or not the properties of each object match.</returns>
    public static bool GetDifferentProperties<T> ( T object1 , T object2 , out List<PropertyInfo> propertyInfoList )
        where T : class
    {
        return GetDifferentProperties<T>( object1 , object2 , null , out propertyInfoList );
    }

    /// <summary>
    /// Compares the public properties of any 2 objects and determines if the properties of each
    /// all contain the same value.
    /// <para> 
    /// In cases where object1 and object2 are of different Types (both being derived from Type T) 
    /// we will cast both objects down to the base Type T to ensure the property comparison is only 
    /// completed on COMMON properties.
    /// (ex. Type T is Foo, object1 is GoodFoo and object2 is BadFoo -- both being inherited from Foo --
    /// both objects will be cast to Foo for comparison)
    /// </para>
    /// </summary>
    /// <typeparam name="T">Any class with public properties.</typeparam>
    /// <param name="object1">Object to compare to object2.</param>
    /// <param name="object2">Object to compare to object1.</param>
    /// <param name="ignoredProperties">A list of <see cref="PropertyInfo"/> objects
    /// to ignore when completing the comparison.</param>
    /// <param name="propertyInfoList">A List of <see cref="PropertyInfo"/> objects that contain data on the properties
    /// from object1 that are not equal to the corresponding properties of object2.</param>
    /// <returns>A boolean value indicating whether or not the properties of each object match.</returns>
    public static bool GetDifferentProperties<T> ( T object1 , T object2 , List<PropertyInfo> ignoredProperties , out List<PropertyInfo> propertyInfoList )
        where T : class
    {
        propertyInfoList = new List<PropertyInfo>();

        // If either object is null, we can't compare anything
        if ( object1 == null || object2 == null )
        {
            return false;
        }

        Type object1Type = object1.GetType();
        Type object2Type = object2.GetType();

        // In cases where object1 and object2 are of different Types (both being derived from Type T) 
        // we will cast both objects down to the base Type T to ensure the property comparison is only 
        // completed on COMMON properties.
        // (ex. Type T is Foo, object1 is GoodFoo and object2 is BadFoo -- both being inherited from Foo --
        // both objects will be cast to Foo for comparison)
        if ( object1Type != object2Type )
        {
            object1Type = typeof ( T );
            object2Type = typeof ( T );
        }

        // Remove any properties to be ignored
        List<PropertyInfo> comparisonProps =
            RemoveProperties( object1Type.GetProperties() , ignoredProperties );

        foreach ( PropertyInfo object1Prop in comparisonProps )
        {
            Type propertyType = null;
            object object1PropValue = null;
            object object2PropValue = null;

            // Rule out an attempt to check against a property which requires
            // an index, such as one accessed via this[]
            if ( object1Prop.GetIndexParameters().GetLength( 0 ) == 0 )
            {
                // Get the value of each property
                object1PropValue = object1Prop.GetValue( object1 , null );
                object2PropValue = object2Type.GetProperty( object1Prop.Name ).GetValue( object2 , null );

                // As we are comparing 2 objects of the same type we know
                // that they both have the same properties, so grab the
                // first non-null value
                if ( object1PropValue != null )
                    propertyType = object1PropValue.GetType().GetInterface( "IComparable" );

                if ( propertyType == null )
                    if ( object2PropValue != null )
                        propertyType = object2PropValue.GetType().GetInterface( "IComparable" );
            }

            // If both objects have null values or were indexed properties, don't continue
            if ( propertyType != null )
            {
                // If one property value is null and the other is not null, 
                // they aren't equal; this is done here as a native CompareTo
                // won't work with a null value as the target
                if ( object1PropValue == null || object2PropValue == null )
                {
                    propertyInfoList.Add( object1Prop );
                }
                else
                {
                    // Use the native CompareTo method
                    MethodInfo nativeCompare = propertyType.GetMethod( "CompareTo" );

                    // Sanity Check:
                    // If we don't have a native CompareTo OR both values are null, we can't compare;
                    // hence, we can't confirm the values differ... just go to the next property
                    if ( nativeCompare != null )
                    {
                        // Return the native CompareTo result
                        bool equal = ( 0 == (int) ( nativeCompare.Invoke( object1PropValue , new object[] {object2PropValue} ) ) );

                        if ( !equal )
                        {
                            propertyInfoList.Add( object1Prop );
                        }
                    }
                }
            }
        }
        return propertyInfoList.Count == 0;
    }

    /// <summary>
    /// Compares the public properties of any 2 objects and determines if the properties of each
    /// all contain the same value.
    /// <para> 
    /// In cases where object1 and object2 are of different Types (both being derived from Type T) 
    /// we will cast both objects down to the base Type T to ensure the property comparison is only 
    /// completed on COMMON properties.
    /// (ex. Type T is Foo, object1 is GoodFoo and object2 is BadFoo -- both being inherited from Foo --
    /// both objects will be cast to Foo for comparison)
    /// </para>
    /// </summary>
    /// <typeparam name="T">Any class with public properties.</typeparam>
    /// <param name="object1">Object to compare to object2.</param>
    /// <param name="object2">Object to compare to object1.</param>
    /// <returns>A boolean value indicating whether or not the properties of each object match.</returns>
    public static bool HasSamePropertyValues<T> ( T object1 , T object2 )
        where T : class
    {
        return HasSamePropertyValues<T>( object1 , object2 , null );
    }

    /// <summary>
    /// Compares the public properties of any 2 objects and determines if the properties of each
    /// all contain the same value.
    /// <para> 
    /// In cases where object1 and object2 are of different Types (both being derived from Type T) 
    /// we will cast both objects down to the base Type T to ensure the property comparison is only 
    /// completed on COMMON properties.
    /// (ex. Type T is Foo, object1 is GoodFoo and object2 is BadFoo -- both being inherited from Foo --
    /// both objects will be cast to Foo for comparison)
    /// </para>
    /// </summary>
    /// <typeparam name="T">Any class with public properties.</typeparam>
    /// <param name="object1">Object to compare to object2.</param>
    /// <param name="object2">Object to compare to object1.</param>
    /// <param name="ignoredProperties">A list of <see cref="PropertyInfo"/> objects
    /// to ignore when completing the comparison.</param>
    /// <returns>A boolean value indicating whether or not the properties of each object match.</returns>
    public static bool HasSamePropertyValues<T> ( T object1 , T object2 , List<PropertyInfo> ignoredProperties )
        where T : class
    {

        // If either object is null, we can't compare anything
        if ( object1 == null || object2 == null )
        {
            return false;
        }

        Type object1Type = object1.GetType();
        Type object2Type = object2.GetType();

        // In cases where object1 and object2 are of different Types (both being derived from Type T) 
        // we will cast both objects down to the base Type T to ensure the property comparison is only 
        // completed on COMMON properties.
        // (ex. Type T is Foo, object1 is GoodFoo and object2 is BadFoo -- both being inherited from Foo --
        // both objects will be cast to Foo for comparison)
        if ( object1Type != object2Type )
        {
            object1Type = typeof ( T );
            object2Type = typeof ( T );
        }

        // Remove any properties to be ignored
        List<PropertyInfo> comparisonProps =
            RemoveProperties( object1Type.GetProperties() , ignoredProperties );

        foreach ( PropertyInfo object1Prop in comparisonProps )
        {
            Type propertyType = null;
            object object1PropValue = null;
            object object2PropValue = null;

            // Rule out an attempt to check against a property which requires
            // an index, such as one accessed via this[]
            if ( object1Prop.GetIndexParameters().GetLength( 0 ) == 0 )
            {
                // Get the value of each property
                object1PropValue = object1Prop.GetValue( object1 , null );
                object2PropValue = object2Type.GetProperty( object1Prop.Name ).GetValue( object2 , null );

                // As we are comparing 2 objects of the same type we know
                // that they both have the same properties, so grab the
                // first non-null value
                if ( object1PropValue != null )
                    propertyType = object1PropValue.GetType().GetInterface( "IComparable" );

                if ( propertyType == null )
                    if ( object2PropValue != null )
                        propertyType = object2PropValue.GetType().GetInterface( "IComparable" );
            }

            // If both objects have null values or were indexed properties, don't continue
            if ( propertyType != null )
            {
                // If one property value is null and the other is not null, 
                // they aren't equal; this is done here as a native CompareTo
                // won't work with a null value as the target
                if ( object1PropValue == null || object2PropValue == null )
                {
                    return false;
                }

                // Use the native CompareTo method
                MethodInfo nativeCompare = propertyType.GetMethod( "CompareTo" );

                // Sanity Check:
                // If we don't have a native CompareTo OR both values are null, we can't compare;
                // hence, we can't confirm the values differ... just go to the next property
                if ( nativeCompare != null )
                {
                    // Return the native CompareTo result
                    bool equal = ( 0 == (int) ( nativeCompare.Invoke( object1PropValue , new object[] {object2PropValue} ) ) );

                    if ( !equal )
                    {
                        return false;
                    }
                }
            }
        }
        return true;
    }

    /// <summary>
    /// Removes any <see cref="PropertyInfo"/> object in the supplied List of 
    /// properties from the supplied Array of properties.
    /// </summary>
    /// <param name="allProperties">Array containing master list of 
    /// <see cref="PropertyInfo"/> objects.</param>
    /// <param name="propertiesToRemove">List of <see cref="PropertyInfo"/> objects to
    /// remove from the supplied array of properties.</param>
    /// <returns>A List of <see cref="PropertyInfo"/> objects.</returns>
    private static List<PropertyInfo> RemoveProperties (
        IEnumerable<PropertyInfo> allProperties , IEnumerable<PropertyInfo> propertiesToRemove )
    {
        List<PropertyInfo> innerPropertyList = new List<PropertyInfo>();

        // Add all properties to a list for easy manipulation
        foreach ( PropertyInfo prop in allProperties )
        {
            innerPropertyList.Add( prop );
        }

        // Sanity check
        if ( propertiesToRemove != null )
        {
            // Iterate through the properties to ignore and remove them from the list of 
            // all properties, if they exist
            foreach ( PropertyInfo ignoredProp in propertiesToRemove )
            {
                if ( innerPropertyList.Contains( ignoredProp ) )
                {
                    innerPropertyList.Remove( ignoredProp );
                }
            }
        }

        return innerPropertyList;
    }
}

Le vrai problème: comment faire la différence entre deux ensembles?

Le moyen le plus rapide que j'ai trouvé est de convertir d'abord les ensembles en dictionnaires, puis de les différencier. Voici une approche générique:

static IEnumerable<T> DictionaryDiff<K, T>(Dictionary<K, T> d1, Dictionary<K, T> d2)
{
    return from x in d1 where !d2.ContainsKey(x.Key) select x.Value;
}

Ensuite, vous pouvez faire quelque chose comme ceci:

static public IEnumerable<PropertyInfo> PropertyDiff(Type t1, Type t2)
{
    var d1 = t1.GetProperties().ToDictionary(x => x.Name);
    var d2 = t2.GetProperties().ToDictionary(x => x.Name);
    return DictionaryDiff(d1, d2);
}

Oui. Utilisez la réflexion . Avec Reflection, vous pouvez faire des choses comme:

//given object of some type
object myObjectFromSomewhere;
Type myObjOriginalType = myObjectFromSomewhere.GetType();
PropertyInfo[] myProps = myObjOriginalType.GetProperties();

Et puis vous pouvez utiliser les classes PropertyInfo résultantes pour comparer toutes sortes de choses.

Comparaison de deux objets du même type à l'aide de LINQ et de Reflection. NB! Il s'agit essentiellement d'une réécriture de la solution de Jon Skeet, mais avec une syntaxe plus compacte et moderne. Il devrait également générer une IL légèrement plus efficace.

Ca fait plutot comme ca:

public bool ReflectiveEquals(LocalHdTicket serverTicket, LocalHdTicket localTicket)
  {
     if (serverTicket == null && localTicket == null) return true;
     if (serverTicket == null || localTicket == null) return false;

     var firstType = serverTicket.GetType();
     // Handle type mismatch anyway you please:
     if(localTicket.GetType() != firstType) throw new Exception("Trying to compare two different object types!");

     return !(from propertyInfo in firstType.GetProperties() 
              where propertyInfo.CanRead 
              let serverValue = propertyInfo.GetValue(serverTicket, null) 
              let localValue = propertyInfo.GetValue(localTicket, null) 
              where !Equals(serverValue, localValue) 
              select serverValue).Any();
  }

Type.GetProperties listera chacune des propriétés d'un type donné. Utilisez ensuite PropertyInfo.GetValue pour vérifier les valeurs.

Comme beaucoup l'ont mentionné l'approche récursive, c'est la fonction avec laquelle vous pouvez passer le nom recherché et la propriété pour commencer à:

    public static void loopAttributes(PropertyInfo prop, string targetAttribute, object tempObject)
    {
        foreach (PropertyInfo nestedProp in prop.PropertyType.GetProperties())
        {
            if(nestedProp.Name == targetAttribute)
            {
                //found the matching attribute
            }
            loopAttributes(nestedProp, targetAttribute, prop.GetValue(tempObject);
        }
    }

//in the main function
foreach (PropertyInfo prop in rootObject.GetType().GetProperties())
{
    loopAttributes(prop, targetAttribute, rootObject);
}