Is there a way to Include() all with dbcontext?

Question

When querying a DbContext with eager loading, it is required to Include("Navigation") in order to populate Navigation Properties. However on some occasions I would like to simply Include all navigation properties for an entity. Is there a method for this, or a way to do it? I'm assuming you could with reflection, but I would prefer to avoid that.

What I know:

var entity = db.Table.Include("Navigation1").Include("Navigation2").First();

What I want:

var entity = db.Table.IncludeAll().First(); 

Prefigure

I worked on an EF4 project where we created a method to do this, but I recommend against it. It used reflection to walk through the entity properties, and then call .Include() on ones that implemented IObjectWithChangeTracker or ObservableCollection. It was very convenient, but it caused some odd side-effects that resulted in inefficient queries. – Subaudition

Answer 1

No. There is not. Entity Framework intentionally makes you be explicit about what you want to eager-load because adding joins makes your query heavier and slower. This is to protect you from yourself. If you need the joins, fine, but at least you'll know exactly how many you're incurring and why, when you specify them explicitly.

Parentage

Thanks for the response. It just seems weird to me, all of these things that essentially say: We didn't make this a feature because we don't trust you to not screw yourself over. P.S. Thanks again for the earlier answer, I'm loving Knockout! – Prefigure

It's actually very common in frameworks. They're opinionated things by nature. It's written to do things as the developers think it should be done. However, the sad truth is that end-users as a rule, will shoot themselves in the foot of you give them a gun. Eager- Loading everything is a big gun. – Parentage

@Prefigure Its not even that. Its almost too easy to create a database where you end up with cycles or hierarchies. At which point..what do you want EF to do? – Thicken

@ChrisPratt I think having the opinion "I don't want to download the entire database" is pretty fair. Since it would defeat the point of an ORM/Database. – Thicken

@Aron: Well, yeah. I would agree. However, I just found out recently that CakePHP actually does let you do this. Of course, what would you expect from PHP ;). – Parentage

Answer 2

No matter what the designers of Entity Framework thought, I found that there is a legitimate use-case for recursively, eagerly loading of all database items: Creating a snapshot of database content that can be easily restored by automated tests. If that is what you are after, you might find this article very interesting as well as this extension method:

public static class EfExtensions
{
    public static IQueryable<TEntity> IncludeAllRecursively<TEntity>(this IQueryable<TEntity> queryable, 
        int maxDepth = int.MaxValue, bool addSeenTypesToIgnoreList = true, HashSet<Type>? ignoreTypes = null)
        where TEntity : class
    {
        var type = typeof(TEntity);
        var includes = new List<string>();
        ignoreTypes ??= new HashSet<Type>();
        GetIncludeTypes(ref includes, prefix: string.Empty, type, ref ignoreTypes, addSeenTypesToIgnoreList, maxDepth);
        foreach (var include in includes)
        {
            queryable = queryable.Include(include);
        }

        return queryable;
    }

    private static void GetIncludeTypes(ref List<string> includes, string prefix, Type type, ref HashSet<Type> ignoreSubTypes, 
        bool addSeenTypesToIgnoreList = true, int maxDepth = int.MaxValue)
    {
        var properties = type.GetProperties();
        foreach (var property in properties)
        {
            var getter = property.GetGetMethod();
            if (getter != null)
            {
                var isVirtual = getter.IsVirtual;
                if (isVirtual)
                {
                    var propPath = (prefix + "." + property.Name).TrimStart('.');
                    if (maxDepth <= propPath.Count(c => c == '.')) { break; }

                    includes.Add(propPath);
                    
                    var subType = property.PropertyType;
                    if (ignoreSubTypes.Contains(subType))
                    {
                        continue;
                    }
                    else if (addSeenTypesToIgnoreList)
                    {
                        // add each type that we have processed to ignore list to prevent recursions
                        ignoreSubTypes.Add(type);
                    }

                    var isEnumerableType = subType.GetInterface(nameof(IEnumerable)) != null;
                    var genericArgs = subType.GetGenericArguments();
                    if (isEnumerableType && genericArgs.Length == 1)
                    {
                        // sub property is collection, use collection type and drill down
                        var subTypeCollection = genericArgs[0];
                        if (subTypeCollection != null)
                        {
                            GetIncludeTypes(ref includes, propPath, subTypeCollection, ref ignoreSubTypes, addSeenTypesToIgnoreList, maxDepth);
                        }
                    }
                    else
                    {
                        // sub property is no collection, drill down directly
                        GetIncludeTypes(ref includes, propPath, subType, ref ignoreSubTypes, addSeenTypesToIgnoreList, maxDepth);
                    }
                }
            }
        }
    }
}

Notes: Avoiding loops while walking through database items is essential. By default it is done using ignore list ignoreSubTypes: Each seen type is added. This might not work always (e.g. when an item "Letter" contains "Sender" and "Recipient" both of type Person). In this case you can try using maxDepth. Good luck, but don't shoot yourself!

Hyperkinesia

Answer 3

A simple option would be to use reflection to check for properties that are virtual.

public static IQueryable<T> IncludeAlla<T>(this IQueryable<T> queryable) where T : class
{
    var type = typeof(T);
    var properties = type.GetProperties();
    foreach (var property in properties)
    {
        var isVirtual = property.GetGetMethod().IsVirtual;
        if (isVirtual)
        {
            queryable = queryable.Include(property.Name);
        }
    }
    return queryable;
}

Selfexcited

Actually, this will not include navigation properties of the children, but only eagerly load with depth one. – Idolater