The line dataContext.Entry(this).Property(property).IsModified = true; is causing this error below. This doesn't happen with non foreign key properties. Any clue why?
The property 'RankingId' on entity type 'TeamOrganizationSeason'
cannot be used for objects of type Nullable1 because it is a
property for objects of type Nullable1.
public class TeamOrganizationSeason
{
public int? RankingId { get; set; }
[ForeignKey("RankingId")]
public Ranking Ranking { get; set; }
public void IsUpdated(TeamOrganizationSeason teamOrganizationSeason, DataContext dataContext)
{
Update(RankingId, teamOrganizationSeason.RankingId, dataContext, t => t.RankingId);
}
private void Update(double? current, double? original, DataContext dataContext, Expression<Func<TeamOrganizationSeason, double?>> property)
{
if (current != original)
{
var state = dataContext.Entry(this).State;
dataContext.TeamOrganizationSeasons.Attach(this);
dataContext.Entry(this).Property(property).IsModified = true;
};
}
}
This had to do not with nullable issues but with different types. An int being sent instead of a double was causing this error. So we made it generic and all is well.
Causing Code Error
if (!requestedType.IsAssignableFrom(propertyType))
{
throw Error.DbEntityEntry_WrongGenericForProp(
propertyName, declaringType.Name, requestedType.Name, propertyType.Name);
}
Generic
private void Update<T>(double? current, double? original, DataContext dataContext, Expression<Func<TeamOrganizationSeason, T>> property)
{
if (current != original)
{
if (dataContext.Entry(this).State == EntityState.Detached)
{
dataContext.TeamOrganizationSeasons.Attach(this);
}
dataContext.Entry(this).Property(property).IsModified = true;
};
}
I'm overriding the ValidateEntity method to check for unique validation and I've hit a stumbling block.
protected override DbEntityValidationResult ValidateEntity(DbEntityEntry entityEntry, IDictionary<object, object> items)
{
var result = new DbEntityValidationResult(entityEntry, new List<DbValidationError>());
if (entityEntry.Entity is ReferenceType && entityEntry.State == EntityState.Added)
{
var entity = entityEntry.Entity as ReferenceType;
var pluralService = PluralizationService.CreateService(CultureInfo.GetCultureInfo("en-gb"));
var pluralEntity = pluralService.Pluralize(entity.GetType().Name);
// I would like Courses to be replaced with the property name of pluralEntity
if (Courses.Where(x => x.Title == entity.Title).Count() > 0)
{
result.ValidationErrors.Add(new DbValidationError(nameof(entity.Title), nameof(entity.Title) + " must be unique."));
}
}
if (result.ValidationErrors.Count > 0)
{
return result;
}
else
{
return base.ValidateEntity(entityEntry, items);
}
}
In my SchoolContext class I have the property DbSet<Course> Courses which is a ReferenceType (a custom abstract class type).
The value of pluralEntity is Courses, but I want to put in the if-statement something similar to:
if (Property(pluralEntity).Where(x => x.Title == entity.Title).Count() > 0)
{
// validate
}
Is there a way to do this?
Update
I've got this:
var prop = (DbSet<ReferenceType>) GetType().GetProperty(pluralEntity).GetValue(this, null);
if (prop.Where(x => x.Title == entity.Title).Count() > 0)
{
result.ValidationErrors.Add(new DbValidationError(nameof(entity.Title), nameof(entity.Title) + " must be unique."));
}
But because ReferenceType is an abstract class it cannot cast it at runtime.
I'd like to do something like this
var prop = (DbSet<typeof(entityEntry.Entity.GetType().Name)>)
But of course that's a variable and can't be passed in as a generic type
The only thing I can think of at the moment is writing a custom validation method, using the repository pattern.
First, create an interface which all your entities will implement
public interface IEntity
{
public string Title {get; set; }
}
Then create the repository:
public class Repository<TEntity> where TEntity: class, IEntity
{
private YourContext context = new YourContext();
private DbSet<TEntity> AppDbSet;
public Repository()
{
AppDbSet = context.Set<TEntity>();
}
//a couple of method to retrieve data...
public List<TEntity> GetAll()
{
return AppDbSet.ToList();
}
public IEnumerable<TEntity> Find(Func<TEntity, bool> predicate)
{
return AppDbSet.Where<TEntity>(predicate);
}
public TEntity Single(Func<TEntity, bool> predicate)
{
return AppDbSet.FirstOrDefault(predicate);
}
//Lastly, implement a validation method
public bool IsValid(TEntity entity)
{
if (AppDbSet.SingleOrDefault(x => x.Title == entity.Title) != null)
return false;
else
return true;
}
}
Use the repository as follow:
Repository<Course> courseRepository = new Repository<Course>();
Course course = new Course();
course.Title = "Boring course";
Console.WriteLine(courseRepository.IsValid(course));
Hope it helps.
I have a generic Update method for Entity Framework in an abstract DatabaseOperations<T,U> class:
public virtual void Update(T updatedObject, int key)
{
if (updatedObject == null)
{
return;
}
using (var databaseContext = new U())
{
databaseContext.Database.Log = Console.Write;
T foundEntity = databaseContext.Set<T>().Find(key);
databaseContext.Entry(foundEntity).CurrentValues.SetValues(updatedObject);
databaseContext.SaveChanges();
}
}
However, this does not handle many-to-many relationships.
This many-to-many update problem can be overcome by overriding the Update method in TrussSetDatabaseOperations : DatabaseOperations<TrussSet, TrussManagementDatabaseContext> to read as follows:
public override void Update(TrussSet updatedTrussSet, int key)
{
if (updatedTrussSet == null)
{
return;
}
using (var databaseContext = new TrussManagementDatabaseContext())
{
databaseContext.Database.Log = Console.Write;
TrussSet foundTrussSet = databaseContext.TrussSets.Find(key);
databaseContext.Entry(foundTrussSet).CurrentValues.SetValues(updatedTrussSet)
// Update the many-to-many relationship of TrussSets to Seals
databaseContext.Entry(foundTrussSet).Collection(trussSet => trussSet.Seals).Load();
databaseContext.Entry(foundTrussSet).Collection(trussSet => trussSet.Seals).CurrentValue = updatedTrussSet.Seals;
databaseContext.SaveChanges();
}
}
However, this overriding would proliferate through all the classes that inherit from DatabaseOperations and have a TrussSet object. Can I somehow inject the added two lines into the generic update method, so that the update method is given the collection properties, loads them, and applies the respective updated collection to that entity? Thanks in advance.
Looking at your code, the following comes to mind:
public virtual void Update(T updatedObject, int key, params string[] navigationProperties) {
if (updatedObject == null) {
return;
}
using (var databaseContext = new U()) {
databaseContext.Database.Log = Console.Write;
T foundEntity = databaseContext.Set<T>().Find(key);
var entry = databaseContext.Entry(foundEntity);
entry.CurrentValues.SetValues(updatedObject);
foreach (var prop in navigationProperties) {
var collection = entry.Collection(prop);
collection.Load();
collection.CurrentValue = typeof(T).GetProperty(prop).GetValue(updatedObject);
}
databaseContext.SaveChanges();
}
}
You can also use Expressions instead of strings (and then extract property names from those expressions) if you want more type-safety.
Update: here is what I mean by "use Expressions" in this case:
public virtual void Update(T updatedObject, int key, params Expression<Func<T, IEnumerable>>[] navigationProperties) {
if (updatedObject == null) {
return;
}
using (var databaseContext = new U()) {
databaseContext.Database.Log = Console.Write;
T foundEntity = databaseContext.Set<T>().Find(key);
var entry = databaseContext.Entry(foundEntity);
entry.CurrentValues.SetValues(updatedObject);
foreach (var prop in navigationProperties) {
string memberName;
var member = prop.Body as MemberExpression;
if (member != null)
memberName = member.Member.Name;
else throw new Exception("One of the navigationProperties is not a member access expression");
var collection = entry.Collection(memberName);
collection.Load();
collection.CurrentValue = typeof (T).GetProperty(memberName).GetValue(updatedObject);
}
databaseContext.SaveChanges();
}
}
I have a detached entity that has a navigation property as such:
public class ClassA
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<ClassB> ClassB
{
get
{
if (_classB == null)
{
var newCollection = new FixupCollection<ClassB>();
newCollection.CollectionChanged += FixupClassB;
_classB = newCollection;
}
return _classB;
}
set
{
if (!ReferenceEquals(_classB, value))
{
var previousValue = _classB as FixupCollection<ClassB>;
if (previousValue != null)
{
previousValue.CollectionChanged -= FixupClassB;
}
_classB = value;
var newValue = value as FixupCollection<ClassB>;
if (newValue != null)
{
newValue.CollectionChanged += ClassB;
}
}
}
}
private ICollection<ClassB> _classB;
private void FixupClassB(object sender, NotifyCollectionChangedEventArgs e)
{
if (e.NewItems != null)
{
foreach (ClassB item in e.NewItems)
{
item.ClassA = this;
}
}
if (e.OldItems != null)
{
foreach (ClassB item in e.OldItems)
{
if (ReferenceEquals(item.ClassA, this))
{
item.ClassA = null;
}
}
}
}
}
My create method works perfectly. It inserts the instance of ObjectA in the database and then inserts instances of ClassB from the collection into the database. The method simply does:
context.ClassA.AddObject(classA);
However, my update method does not insert/update/delete instances of ClassB when I call it. The method is as such:
public virtual void Update(List<ClassA> entities, TrialsContext context)
{
foreach (ClassA entity in entities)
{
ClassA original = context.ObjectA.First(x => x.Id == entity.Id)
if (original != null)
{
context.ObjectA.ApplyOriginalValues(original);
context.ObjectA.ApplyCurrentValues(entity);
}
}
}
Is there any reason why this would fail? It works perfectly when I turn lazy loading off and fully hydrate my entities, however, this is a performance hit. What options do I have?
Must use Self Tracking Entities to accomplish goal.
Given the following objects:
public class Customer {
public String Name { get; set; }
public String Address { get; set; }
}
public class Invoice {
public String ID { get; set; }
public DateTime Date { get; set; }
public Customer BillTo { get; set; }
}
I'd like to use reflection to go through the Invoice to get the Name property of a Customer. Here's what I'm after, assuming this code would work:
Invoice inv = GetDesiredInvoice(); // magic method to get an invoice
PropertyInfo info = inv.GetType().GetProperty("BillTo.Address");
Object val = info.GetValue(inv, null);
Of course, this fails since "BillTo.Address" is not a valid property of the Invoice class.
So, I tried writing a method to split the string into pieces on the period, and walk the objects looking for the final value I was interested in. It works okay, but I'm not entirely comfortable with it:
public Object GetPropValue(String name, Object obj) {
foreach (String part in name.Split('.')) {
if (obj == null) { return null; }
Type type = obj.GetType();
PropertyInfo info = type.GetProperty(part);
if (info == null) { return null; }
obj = info.GetValue(obj, null);
}
return obj;
}
Any ideas on how to improve this method, or a better way to solve this problem?
EDIT after posting, I saw a few related posts... There doesn't seem to be an answer that specifically addresses this question, however. Also, I'd still like the feedback on my implementation.
I use following method to get the values from (nested classes) properties like
"Property"
"Address.Street"
"Address.Country.Name"
public static object GetPropertyValue(object src, string propName)
{
if (src == null) throw new ArgumentException("Value cannot be null.", "src");
if (propName == null) throw new ArgumentException("Value cannot be null.", "propName");
if(propName.Contains("."))//complex type nested
{
var temp = propName.Split(new char[] { '.' }, 2);
return GetPropertyValue(GetPropertyValue(src, temp[0]), temp[1]);
}
else
{
var prop = src.GetType().GetProperty(propName);
return prop != null ? prop.GetValue(src, null) : null;
}
}
Here is the Fiddle: https://dotnetfiddle.net/PvKRH0
I know I'm a bit late to the party, and as others said, your implementation is fine
...for simple use cases.
However, I've developed a library that solves exactly that use case, Pather.CSharp.
It is also available as Nuget Package.
Its main class is Resolver with its Resolve method.
You pass it an object and the property path, and it will return the desired value.
Invoice inv = GetDesiredInvoice(); // magic method to get an invoice
var resolver = new Resolver();
object result = resolver.Resolve(inv, "BillTo.Address");
But it can also resolve more complex property paths, including array and dictionary access.
So, for example, if your Customer had multiple addresses
public class Customer {
public String Name { get; set; }
public IEnumerable<String> Addresses { get; set; }
}
you could access the second one using Addresses[1].
Invoice inv = GetDesiredInvoice(); // magic method to get an invoice
var resolver = new Resolver();
object result = resolver.Resolve(inv, "BillTo.Addresses[1]");
I actually think your logic is fine. Personally, I would probably change it around so you pass the object as the first parameter (which is more inline with PropertyInfo.GetValue, so less surprising).
I also would probably call it something more like GetNestedPropertyValue, to make it obvious that it searches down the property stack.
You have to access the ACTUAL object that you need to use reflection on. Here is what I mean:
Instead of this:
Invoice inv = GetDesiredInvoice(); // magic method to get an invoice
PropertyInfo info = inv.GetType().GetProperty("BillTo.Address");
Object val = info.GetValue(inv, null);
Do this (edited based on comment):
Invoice inv = GetDesiredInvoice(); // magic method to get an invoice
PropertyInfo info = inv.GetType().GetProperty("BillTo");
Customer cust = (Customer)info.GetValue(inv, null);
PropertyInfo info2 = cust.GetType().GetProperty("Address");
Object val = info2.GetValue(cust, null);
Look at this post for more information:
Using reflection to set a property of a property of an object
In hopes of not sounding too late to the party, I would like to add my solution:
Definitely use recursion in this situation
public static Object GetPropValue(String name, object obj, Type type)
{
var parts = name.Split('.').ToList();
var currentPart = parts[0];
PropertyInfo info = type.GetProperty(currentPart);
if (info == null) { return null; }
if (name.IndexOf(".") > -1)
{
parts.Remove(currentPart);
return GetPropValue(String.Join(".", parts), info.GetValue(obj, null), info.PropertyType);
} else
{
return info.GetValue(obj, null).ToString();
}
}
You don't explain the source of your "discomfort," but your code basically looks sound to me.
The only thing I'd question is the error handling. You return null if the code tries to traverse through a null reference or if the property name doesn't exist. This hides errors: it's hard to know whether it returned null because there's no BillTo customer, or because you misspelled it "BilTo.Address"... or because there is a BillTo customer, and its Address is null! I'd let the method crash and burn in these cases -- just let the exception escape (or maybe wrap it in a friendlier one).
Here is another implementation that will skip a nested property if it is an enumerator and continue deeper. Properties of type string are not affected by the Enumeration Check.
public static class ReflectionMethods
{
public static bool IsNonStringEnumerable(this PropertyInfo pi)
{
return pi != null && pi.PropertyType.IsNonStringEnumerable();
}
public static bool IsNonStringEnumerable(this object instance)
{
return instance != null && instance.GetType().IsNonStringEnumerable();
}
public static bool IsNonStringEnumerable(this Type type)
{
if (type == null || type == typeof(string))
return false;
return typeof(IEnumerable).IsAssignableFrom(type);
}
public static Object GetPropValue(String name, Object obj)
{
foreach (String part in name.Split('.'))
{
if (obj == null) { return null; }
if (obj.IsNonStringEnumerable())
{
var toEnumerable = (IEnumerable)obj;
var iterator = toEnumerable.GetEnumerator();
if (!iterator.MoveNext())
{
return null;
}
obj = iterator.Current;
}
Type type = obj.GetType();
PropertyInfo info = type.GetProperty(part);
if (info == null) { return null; }
obj = info.GetValue(obj, null);
}
return obj;
}
}
based on this question and on
How to know if a PropertyInfo is a collection
by Berryl
I use this in a MVC project to dynamically Order my data by simply passing the Property to sort by
Example:
result = result.OrderBy((s) =>
{
return ReflectionMethods.GetPropValue("BookingItems.EventId", s);
}).ToList();
where BookingItems is a list of objects.
> Get Nest properties e.g., Developer.Project.Name
private static System.Reflection.PropertyInfo GetProperty(object t, string PropertName)
{
if (t.GetType().GetProperties().Count(p => p.Name == PropertName.Split('.')[0]) == 0)
throw new ArgumentNullException(string.Format("Property {0}, is not exists in object {1}", PropertName, t.ToString()));
if (PropertName.Split('.').Length == 1)
return t.GetType().GetProperty(PropertName);
else
return GetProperty(t.GetType().GetProperty(PropertName.Split('.')[0]).GetValue(t, null), PropertName.Split('.')[1]);
}
if (info == null) { /* throw exception instead*/ }
I would actually throw an exception if they request a property that doesn't exist. The way you have it coded, if I call GetPropValue and it returns null, I don't know if that means the property didn't exist, or the property did exist but it's value was null.
public static string GetObjectPropertyValue(object obj, string propertyName)
{
bool propertyHasDot = propertyName.IndexOf(".") > -1;
string firstPartBeforeDot;
string nextParts = "";
if (!propertyHasDot)
firstPartBeforeDot = propertyName.ToLower();
else
{
firstPartBeforeDot = propertyName.Substring(0, propertyName.IndexOf(".")).ToLower();
nextParts = propertyName.Substring(propertyName.IndexOf(".") + 1);
}
foreach (var property in obj.GetType().GetProperties())
if (property.Name.ToLower() == firstPartBeforeDot)
if (!propertyHasDot)
if (property.GetValue(obj, null) != null)
return property.GetValue(obj, null).ToString();
else
return DefaultValue(property.GetValue(obj, null), propertyName).ToString();
else
return GetObjectPropertyValue(property.GetValue(obj, null), nextParts);
throw new Exception("Property '" + propertyName.ToString() + "' not found in object '" + obj.ToString() + "'");
}
I wanted to share my solution although it may be too late. This solution is primarily to check if the nested property exists. But it can be easily tweaked to return the property value if needed.
private static PropertyInfo _GetPropertyInfo(Type type, string propertyName)
{
//***
//*** Check if the property name is a complex nested type
//***
if (propertyName.Contains("."))
{
//***
//*** Get the first property name of the complex type
//***
var tempPropertyName = propertyName.Split(".", 2);
//***
//*** Check if the property exists in the type
//***
var prop = _GetPropertyInfo(type, tempPropertyName[0]);
if (prop != null)
{
//***
//*** Drill down to check if the nested property exists in the complex type
//***
return _GetPropertyInfo(prop.PropertyType, tempPropertyName[1]);
}
else
{
return null;
}
}
else
{
return type.GetProperty(propertyName, BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.Instance);
}
}
I had to refer to few posts to come up with this solution. I think this will work for multiple nested property types.
My internet connection was down when I need to solve the same problem, so I had to 're-invent the wheel':
static object GetPropertyValue(Object fromObject, string propertyName)
{
Type objectType = fromObject.GetType();
PropertyInfo propInfo = objectType.GetProperty(propertyName);
if (propInfo == null && propertyName.Contains('.'))
{
string firstProp = propertyName.Substring(0, propertyName.IndexOf('.'));
propInfo = objectType.GetProperty(firstProp);
if (propInfo == null)//property name is invalid
{
throw new ArgumentException(String.Format("Property {0} is not a valid property of {1}.", firstProp, fromObject.GetType().ToString()));
}
return GetPropertyValue(propInfo.GetValue(fromObject, null), propertyName.Substring(propertyName.IndexOf('.') + 1));
}
else
{
return propInfo.GetValue(fromObject, null);
}
}
Pretty sure this solves the problem for any string you use for property name, regardless of extent of nesting, as long as everything's a property.
Based on the original code from #jheddings, I have created a extension method version with generic type and verifications:
public static T GetPropertyValue<T>(this object sourceObject, string propertyName)
{
if (sourceObject == null) throw new ArgumentNullException(nameof(sourceObject));
if (string.IsNullOrWhiteSpace(propertyName)) throw new ArgumentException(nameof(propertyName));
foreach (string currentPropertyName in propertyName.Split('.'))
{
if (string.IsNullOrWhiteSpace(currentPropertyName)) throw new InvalidOperationException($"Invalid property '{propertyName}'");
PropertyInfo propertyInfo = sourceObject.GetType().GetProperty(currentPropertyName);
if (propertyInfo == null) throw new InvalidOperationException($"Property '{currentPropertyName}' not found");
sourceObject = propertyInfo.GetValue(sourceObject);
}
return sourceObject is T result ? result : default;
}
I wrote a method that received one object type as the argument from the input and returns dictionary<string,string>
public static Dictionary<string, string> GetProperties(Type placeHolderType)
{
var result = new Dictionary<string, string>();
var properties = placeHolderType.GetProperties();
foreach (var propertyInfo in properties)
{
string name = propertyInfo.Name;
string description = GetDescriptionTitle(propertyInfo);
if (IsNonString(propertyInfo.PropertyType))
{
var list = GetProperties(propertyInfo.PropertyType);
foreach (var item in list)
{
result.Add($"{propertyInfo.PropertyType.Name}_{item.Key}", item.Value);
}
}
else
{
result.Add(name, description);
}
}
return result;
}
public static bool IsNonString(Type type)
{
if (type == null || type == typeof(string))
return false;
return typeof(IPlaceHolder).IsAssignableFrom(type);
}
private static string GetDescriptionTitle(MemberInfo memberInfo)
{
if (Attribute.GetCustomAttribute(memberInfo, typeof(DescriptionAttribute)) is DescriptionAttribute descriptionAttribute)
{
return descriptionAttribute.Description;
}
return memberInfo.Name;
}
public static object GetPropertyValue(object src, string propName)
{
if (src == null) throw new ArgumentException("Value cannot be null.", "src");
if (propName == null) throw new ArgumentException("Value cannot be null.", "propName");
var prop = src.GetType().GetProperty(propName);
if (prop != null)
{
return prop.GetValue(src, null);
}
else
{
var props = src.GetType().GetProperties();
foreach (var property in props)
{
var propInfo = src.GetType().GetProperty(property.Name);
if (propInfo != null)
{
var propVal = propInfo.GetValue(src, null);
if (src.GetType().GetProperty(property.Name).PropertyType.IsClass)
{
return GetPropertyValue(propVal, propName);
}
return propVal;
}
}
return null;
}
usage: calling part
var emp = new Employee() { Person = new Person() { FirstName = "Ashwani" } };
var val = GetPropertyValue(emp, "FirstName");
above can search the property value at any level
Try inv.GetType().GetProperty("BillTo+Address");