Until now I don't find any simple working solution for a dynamic include in Entity Framwework Core 2.1. Below is a simple case where I put the Include in another line that doesn't work.
string[] includes = new[] { "navigationprop" };
var query = _dbContext.Set<T>();
query.Include(includes[0]);
This work:
var query = _dbContext.Set<T>().Include(includes[0]);
In this answer is a similar issue but i think it's too over.
Related
Background
I got a page where I’m showing two list views from two separate lists which both have Custom List as their ListTemplate. They got their separate jslink file cause I don’t want them to look alike.
Problem
The js link file targets both listviews since they use the same Template.
Code
(function () {
var listContext = {};
listContext.Templates = {};
listContext.ListTemplateType = 100;
listContext.Templates.Header = "<div><ul>";
listContext.Templates.Footer = "</ul></div>";
listContext.Templates.Item = LinkTemplate;
SPClientTemplates.TemplateManager.RegisterTemplateOverrides(listContext);
})();
Question
Is there any way to make the js only target a specific list?
Ended up going with Paul Hunts solution that he writes about on myfatblog.co.uk. http://www.myfatblog.co.uk/index.php/2013/09/listview-web-part-issues-with-jslink-and-display-templates-a-solution/
The script ended up looking like this and I pasted it into the jslink function where I define what listContext to override.
// Override the RenderListView once the ClientTemplates.JS has been called
ExecuteOrDelayUntilScriptLoaded(function(){
// Copy and override the existing RenderListView
var oldRenderListView = RenderListView;
RenderListView = function(ctx,webPartID)
{
// Check the title and set the BaseViewId
if (ctx.ListTitle == "List")
ctx.BaseViewID = "list";
//now call the original RenderListView
oldRenderListView(ctx,webPartID);
}
},"ClientTemplates.js");
I am using Entity Framework 5 (DBContext) and I am trying to find the best way to deep copy an entity (i.e. copy the entity and all related objects) and then save the new entities in the database. How can I do this? I have looked into using extension methods such as CloneHelper but I am not sure if it applies to DBContext.
One cheap easy way of cloning an entity is to do something like this:
var originalEntity = Context.MySet.AsNoTracking()
.FirstOrDefault(e => e.Id == 1);
Context.MySet.Add(originalEntity);
Context.SaveChanges();
the trick here is AsNoTracking() - when you load an entity like this, your context do not know about it and when you call SaveChanges, it will treat it like a new entity.
If MySet has a reference to MyProperty and you want a copy of it too, just use an Include:
var originalEntity = Context.MySet.Include("MyProperty")
.AsNoTracking()
.FirstOrDefault(e => e.Id == 1);
Here's another option.
I prefer it in some cases because it does not require you to run a query specifically to get data to be cloned. You can use this method to create clones of entities you've already obtained from the database.
//Get entity to be cloned
var source = Context.ExampleRows.FirstOrDefault();
//Create and add clone object to context before setting its values
var clone = new ExampleRow();
Context.ExampleRows.Add(clone);
//Copy values from source to clone
var sourceValues = Context.Entry(source).CurrentValues;
Context.Entry(clone).CurrentValues.SetValues(sourceValues);
//Change values of the copied entity
clone.ExampleProperty = "New Value";
//Insert clone with changes into database
Context.SaveChanges();
This method copies the current values from the source to a new row that has been added.
This is a generic extension method which allows generic cloning.
You have to fetch System.Linq.Dynamic from nuget.
public TEntity Clone<TEntity>(this DbContext context, TEntity entity) where TEntity : class
{
var keyName = GetKeyName<TEntity>();
var keyValue = context.Entry(entity).Property(keyName).CurrentValue;
var keyType = typeof(TEntity).GetProperty(keyName, System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance).PropertyType;
var dbSet = context.Set<TEntity>();
var newEntity = dbSet
.Where(keyName + " = #0", keyValue)
.AsNoTracking()
.Single();
context.Entry(newEntity).Property(keyName).CurrentValue = keyType.GetDefault();
context.Add(newEntity);
return newEntity;
}
The only thing you have to implement yourself is the GetKeyName method. This could be anything from return typeof(TEntity).Name + "Id" to return the first guid property or return the first property marked with DatabaseGenerated(DatabaseGeneratedOption.Identity)].
In my case I already marked my classes with [DataServiceKeyAttribute("EntityId")]
private string GetKeyName<TEntity>() where TEntity : class
{
return ((DataServiceKeyAttribute)typeof(TEntity)
.GetCustomAttributes(typeof(DataServiceKeyAttribute), true).First())
.KeyNames.Single();
}
I had the same issue in Entity Framework Core where deep clone involves multiple steps when children entities are lazy loaded. One way to clone the whole structure is the following:
var clonedItem = Context.Parent.AsNoTracking()
.Include(u => u.Child1)
.Include(u => u.Child2)
// deep includes might go here (see ThenInclude)
.FirstOrDefault(u => u.ParentId == parentId);
// remove old id from parent
clonedItem.ParentId = 0;
// remove old ids from children
clonedItem.Parent1.ForEach(x =>
{
x.Child1Id = 0;
x.ParentId= 0;
});
clonedItem.Parent2.ForEach(x =>
{
x.Child2Id = 0;
x.ParentId= 0;
});
// customize entities before inserting it
// mark everything for insert
Context.Parent.Add(clonedItem);
// save everything in one single transaction
Context.SaveChanges();
Of course, there are ways to make generic functions to eager load everything and/or reset values for all keys, but this should make all the steps much clear and customizable (e.g. all for some children to not be cloned at all, by skipping their Include).
I'm trying to retrieve a list of entities from CRM, but I'd like to get each one with the related entities. So far, I've the following code:
FilterExpression filterExpression = new FilterExpression();
ConditionExpression condition = new ConditionExpression(Constants.ModifiedOnAttribute, ConditionOperator.GreaterEqual, lastSync);
filterExpression.AddCondition(condition);
QueryExpression query = new QueryExpression()
{
EntityName = entityName,
ColumnSet = new ColumnSet(attributesMetadata.Select(att => att.Name).ToArray<string>()),
Criteria = filterExpression,
Distinct = false,
NoLock = true
};
RetrieveMultipleRequest multipleRequest = new RetrieveMultipleRequest();
multipleRequest.Query = queryExpression;
RetrieveMultipleResponse response = (RetrieveMultipleResponse)proxy.Execute(multipleRequest);
In the variable response, I can see the EntityCollection attribute, but inside, Related entities always come empty.
I'd like to know if it is possible to retrieve the set of a given entities, with the related entities, using RetrieveMultipleRequest, rather than go one by one using RetrieveRequest.
One approach to retreive related entities data - adding LinkEntities to your query. Example below will make you an idea how to make this:
LinkEntity linkEntity = new LinkEntity("email", "new_emails", "activityid", "new_relatedemail", JoinOperator.Inner);
linkEntity.Columns.AddColumn("versionnumber");
linkEntity.Columns.AddColumn("new_emailsid");
linkEntity.EntityAlias = "related";
query = new QueryExpression("email");
query.ColumnSet.AddColumn("activityid");
query.ColumnSet.AddColumn("versionnumber");
query.Criteria.AddCondition("modifiedon", ConditionOperator.NotNull);
query.LinkEntities.Add(linkEntity);
And then you can access attributes from related entities using EntityAlias you specified above:
foreach (Entity entity in entities.Entities)
{
if ((long)(entity["related.versionnumber"] as AliasedValue).Value > 0)
{
stop = false;
}
}
The RetrieveMultipleRequest is for returning multiple instances of a particular type of entity. I have spent a year using the CRM SDK from C# and I have found no way of populating those related entity collections in a single query. This basically leaves you with two options:
Use the AliasedValue as SergeyS recommends. Remember when querying 1:Many relationships, be aware that you could be returning multiple results for the same parent entity. This is what I use most of the time.
Perform a second query for each relationship you want access to. You'll probably get better performance if you can use an IN statement in your second query, based on the results of the first, rather than performing a separate query for each result of the first.
Below is some pseudo code to show the difference.
var contacts = GetContacts();
// One Request to get the cars for the contacts
var cars = GetCarsWhereContactIdIn(contacts.Select( c => c.new_ContactId));
foreach(var c in contacts){
c.new_Cars.AddRange(cars.where(car => car.new_contactId = c.ContactId));
}
// Verses
var contacts = GetContacts();
foreach(var c in contacts){
// One Request for each contact
c.new_Cars.AddRange(GetCarsForContact(c.ContactId));
}
I am very confused, i am trying in vain to queue up multiple inserts i have thousands of adds to do so i only want to really do the database once.
I am using .net 4 and entity framework 4 and also added reference to system.data.objects
but i still have no overload available for SaveChanges
here is my code:
using (TransactionScope scope = new TransactionScope())
{
using (myDbContext context = new myDbContext)
{
foreach (var p in model)
{
var tempProduct = new Products();
// set a loopable list of available products
IEnumerable<MerchantProductFeedMerchantProd> prod = p.prod;
foreach (var i in prod)
{
var prodText = i.text.FirstOrDefault();
var prodUri = i.uri.FirstOrDefault();
var prodPrice = i.price.FirstOrDefault();
FillTempProduct(feedId, i, tempProduct, supplierId, feedInfo, prodPrice, prodText,
prodUri);
context.Products.Add(tempProduct);
context.SaveChanges(false); // no overload
}
scope.Complete();
context.AcceptAllChanges(); //acceptallchanges not referenced ??
}
}
this is really battering my head now, so any help would be much appreciated.
thanks
Because you are using DbContext API and these methods are from ObjectContext API. DbContext API is simplified = it is only for simple requirements. If you have more complex requirements you must use ObjectContext API by converting your DbContext to ObjectContext instance:
var objectContext = ((IObjectContextAdapter)myDbContext).ObjectContext;
I'm trying to use:
var viewEngineResult = ViewEngines.Engines.FindView(ControllerContext, myViewName, null);
as part of a process to render the contents of a view to send nice formatted emails. I'm using it inside an Orchard Controller. I have used similar code outside of Orchard in an MVC project and it works fine.
However in Orchard running this code fails to find the view I'm looking for and returns a view engine result that has searched 0 locations.
viewEngineResult has the following values after it is called:
SearchedLocations: Count = 0,
View: null,
ViewEngine: null
Is there a reason this doesn't work in Orchard and is there a way to make it work?
This answer is based on the advise given me by Bertrand, but I wanted to bring it together with what I'd discovered.
To be able to use FindPartialView I needed to inject an instance of IViewEngineProvider into my controller.
I then used the following code to resolve and render a view:
private String RenderView(String viewName, object model)
{
var paths = new List<string>(); // This can just be an empty list and it still finds it.
var viewEngine = _viewEngineProvider.CreateModulesViewEngine(new CreateModulesViewEngineParams {VirtualPaths = paths});
var viewResult = viewEngine.FindPartialView(ControllerContext, viewName, false);
if (viewResult.View == null) {
throw new Exception("Couldn't find view " + viewName);
}
var viewData = new ViewDataDictionary {Model = model};
using (var sw = new StringWriter())
{
var viewContext = new ViewContext(ControllerContext, viewResult.View, viewData, TempData, sw);
viewResult.View.Render(viewContext, sw);
return sw.GetStringBuilder().ToString();
}
}
I think you'll want to take a close look at Orchard.Framework/Mvc/ViewEngines, in particular IViewEngineProvider and ThemeAwareViewEngine. There's a lot more going on when in Orchard, such as themes, multi-tenancy, and a richer environment in general that may be needed to make this work.
What's likely happening here is that the view engines don't have enough information to resolve a view and thus opt out of the chain. You might want to put a breakpoint into ThemeAwareViewEngine.FindView, and then inspect the private dependency fields of that class. I wouldn't be surprised if they were null, because getting to FindView through statics will probably not allow dependency injection to do its stuff properly.
Then again I'm just guessing.