I'm getting the Instance ID of an object from collision_line()
Now that I have this instance, I want to get it's image_angle, but I get an 'unknown variable' message when I try that.
What should I do?
what is the value of this collision_line()? The collision_line() function returns an instance id - however when nothing is found it returns noone (-4).. So you'll have to test for that first:
var inst, imgangle;
inst = collision_line(...);
if (inst != noone) {
imgangle = inst.image_angle;
//etc etc
}
or alternativelly (more cleanly in GM), we can "abuse" the with statement. With executes all following code from the perspective of the given instance id (or for all instances of a certain object when given the object id).
However the value noone will automatically prevent any execution.
var inst, imgangle;
inst = collision_line(...);
with (inst) {
imgangle = image_angle;
//note that we do no longer have to put "inst." before getting a variable
//etc etc
}
Related
I have a field in my database with duplicates. I want to use it in a dropdown list, which has to return distinct data.
Here is the method that I created to do this:
public IEnumerable<SelectListItem> GetBranches(string username)
{
using (var objData = new BranchEntities())
{
IEnumerable<SelectListItem> objdataresult = objData.ABC_USER.Select(c => new SelectListItem
{
Value = c.BRANCH_CODE.ToString(),
Text = c.BRANCH_CODE
}).Distinct(new Reuseablecomp.SelectListItemComparer());
return objdataresult;
}
}
Here is the class I am using:
public static class Reuseablecomp
{
public class SelectListItemComparer : IEqualityComparer<SelectListItem>
{
public bool Equals(SelectListItem x, SelectListItem y)
{
return x.Text == y.Text && x.Value == y.Value;
}
public int GetHashCode(SelectListItem item)
{
int hashText = item.Text == null ? 0 : item.Text.GetHashCode();
int hashValue = item.Value == null ? 0 : item.Value.GetHashCode();
return hashText ^ hashValue;
}
}
}
Nothing is returned and I get the error below. When I try a basic query without Distinct, everything works fine.
{"The operation cannot be completed because the DbContext has been disposed."}
System.Exception {System.InvalidOperationException}
Inner exception = null
How can I return distinct data for my dropdown?
Technically, your problem can be solved simply by appending .ToList() after your Distinct(...) call. The problem is that queries are evaluated JIT (just in time). In other words, until the actual data the query represents is needed, the query is not actually sent to the database. Calling ToList is one such thing that requires the actual data, and therefore will cause the query to be evaluated immediately.
However, the root cause of your problem is that you are doing this within a using statement. When the method exits, the query has not yet been evaluated, but you have now disposed of your context. Therefore, when it comes time to actually evaluate that query, there's no context to do it with and you get that exception. You should really never use a database context in conjuction with using. It's just a recipe for disaster. Your context should ideally be request-scoped and you should use dependency injection to feed it to whatever objects or methods need it.
Also, for what it's worth, you can simply move your Distinct call to before your Select and you won't need a custom IEqualityComparer any more. For example:
var objdataresult = objData.ABC_USER.Distinct().Select(c => new SelectListItem
{
Value = c.BRANCH_CODE.ToString(),
Text = c.BRANCH_CODE
});
Order of ops does matter here. Calling Distinct first includes it as part of the query to the database, but calling it after, as you're doing, runs it on the in-memory collection, once evaluated. The latter requires, then, custom logic to determine what constitutes distinct items in an IEnumerable<SelectListItem>, which is obviously not necessary for the database query version.
I am trying to duplicate an object every time I click it in Verold. I have attached the Object Picker to the scene and successfully triggered a function which prints to the console.
I've tried this code but I get a Type Error - can't read property of undefined.
var xxx = this.getEntity().clone();
var threeDataxxx = xxx.getThreeData();
threeDataxxx.position.x += Math.random() * 5;
The clone() method is asynchronous (because the same method would be used if you were creating persistent copies of your objects on the server). This function, like many functions in the Verold API, takes an 'options' object as a parameter. In here, you need to specify the 'success' callback method like in the following example. Once you have the clone, you then need to add it to the scene hierarchy using the addChild() method. This will automatically trigger the cloned object to load.
var parent = this.getEntity().getParentObject();
this.getEntity().clone( {
success: function( newEntity ) {
parent.addChild( newEntity );
var position = newEntity.getPosition();
position.x += Math.random() * 10;
newEntity.setPosition( position.x, position.y, position.z );
}
});
The multiple steps are useful because you may want to clone several objects and have them ready to add to the scene at a later time.
And, of course, if you don't require the cloned object to have components or any of the other functionality of a VeroldObject, you can always just get the threeData and then use Three.JS's clone() method.
Hope that helps.
My adapter uses findHasMany to load child records for a hasMany relationship.
My findHasMany adapter method is directly based on the test case for findHasMany. It retrieves the contents of the hasMany on demand, and eventually does the following two operations:
store.loadMany(type, hashes);
// ...
store.loadHasMany(record, relationship.key, ids);
(The full code for the findHasMany is below, in case the issue is there, but I don't think so.)
The really strange behavior is: it seems that somewhere within loadHasMany (or in some subsequent async process) only the first and last child records get their inverse belongsTo property set, even though all the child records are added to the hasMany side. I.e., if posts/1 has 10 comments, this is what I get, after everything has loaded:
var post = App.Posts.find('1');
post.get('comments').objectAt(0).get('post'); // <App.Post:ember123:1>
post.get('comments').objectAt(1).get('post'); // null
post.get('comments').objectAt(2).get('post'); // null
// ...
post.get('comments').objectAt(8).get('post'); // null
post.get('comments').objectAt(9).get('post'); // <App.Post:ember123:1>
My adapter is a subclass of DS.RESTAdapter, and I don't think I'm overloading anything in my adapter or serializer that would cause this behavior.
Has anybody seen something like this before? It's weird enough I though someone might know why it's happening.
Extra
Using findHasMany lets me load the contents of the hasMany only when the property is accessed (valuable in my case because calculating the array of IDs would be expensive). So say I have the classic posts/comments example models, the server returns for posts/1:
{
post: {
id: 1,
text: "Linkbait!"
comments: "/posts/1/comments"
}
}
Then my adapter can retrieve /posts/1/comments on demand, which looks like this:
{
comments: [
{
id: 201,
text: "Nuh uh"
},
{
id: 202,
text: "Yeah huh"
},
{
id: 203,
text: "Nazi Germany"
}
]
}
Here is the code for the findHasMany method in my adapter:
findHasMany: function(store, record, relationship, details) {
var type = relationship.type;
var root = this.rootForType(type);
var url = (typeof(details) == 'string' || details instanceof String) ? details : this.buildURL(root);
var query = relationship.options.query ? relationship.options.query(record) : {};
this.ajax(url, "GET", {
data: query,
success: function(json) {
var serializer = this.get('serializer');
var pluralRoot = serializer.pluralize(root);
var hashes = json[pluralRoot]; //FIXME: Should call some serializer method to get this?
store.loadMany(type, hashes);
// add ids to record...
var ids = [];
var len = hashes.length;
for(var i = 0; i < len; i++){
ids.push(serializer.extractId(type, hashes[i]));
}
store.loadHasMany(record, relationship.key, ids);
}
});
}
Solution
Override the DS.RelationshipChange.getByReference method by inserting the following code into your app:
DS.RelationshipChange.prototype.getByReference = function(reference) {
var store = this.store;
// return null or undefined if the original reference was null or undefined
if (!reference) { return reference; }
if (reference.record) {
return reference.record;
}
return store.materializeRecord(reference);
};
Yes, this is overriding a private, internal method in Ember Data. Yes, it may break at any time with any update. I'm pretty sure this is a bug in Ember Data, but I'm not 100% certain this is the right solution. But it does solve this problem, and possibly other relationship-related problems.
This fix is designed to be applied to Ember Data master as of 29 Apr 2013.
Reason
DS.Store.loadHasMany calls DS.Model.hasManyDidChange, which retrieves references for all the child records and then sets the hasMany's content to the array of references. This kicks off a chain of observers., eventually calling DS.ManyArray.arrayContentDidChange, in which the first line is this._super.apply(this, arguments);, calling the superclass method Ember.Array.arrayContentDidChange. That Ember.Array method includes an optimization that caches the first and last object in the array and calls objectAt on only those two array members. So there's the part that singles out the first and last record.
Next, since DS.RecordArray implements an objectAtContent method (from Ember.ArrayProxy), the objectAtContent implementation calls DS.Store.recordForReference, which in turn calls DS.Store.materializeRecord. This last function adds a record property to the reference that is passed in as a side effect.
Now we get to what I think is a bug. In DS.ManyArray.arrayContentDidChange, after calling the superclass method, it loops through all the new references and creates a DS.RelationshipChangeAdd instance that encapsulates the owner and child record references. But the first line inside the loop is:
var reference = get(this, 'content').objectAt(i);
Unlike what happens above to the first and last record, this calls objectAt directly on the Ember.NativeArray and bypasses the ArrayProxy methods including the objectAtContent hook, which means that DS.Store.materializeRecord--which adds the record property on the reference object--may have never been called on some references.
Next, the relationship changes created in the loop are immediately afterward (in the same run loop) applied with this call tree: DS.RelationshipChangeAdd.sync -> DS.RelationshipChange.getFirstRecord -> DS.RelationshipChange.getByReference. This last method expects the reference object to have a record property. However, the record property is only set on the first and last reference objects, for reasons explained above. Therefore, for all but the first and last records, the relationship fails to be established because it doesn't have access to the child record object!
The above fix calls DS.Store.materializeRecord whenever the record property doesn't exist on the reference. The last line in the function is the only thing added. On the one hand, it looks like this was the original intention: that var store = this.store; line in the original declares a variable that isn't otherwise used in the function, so what's it there for? Also, without the added line, the function doesn't always return a value, which is a little unusual for a function which is expected to do so. On the other hand, this could lead to mass materialization in some cases where that would be undesirable (but, the relationships just won't work without it in some cases, it seems).
Possibly related
The "chain of observers" I mentioned takes a bit of an odd path. The initiating event was setting the content property on a DS.ManyArray, which extends Ember.ArrayProxy--therefore the content property has a dependent property arrangedContent. Importantly, the observers on arrangedContent are executed before observers on content are executed (see Ember.propertyDidChange). However, the default implementation of Ember.ArrayProxy.arrangedContentArrayDidChange simply calls Ember.Array.arrayContentDidChange, which DS.ManyArray implements! The point being, this looks like a recipe for some code to execute in an unintended order. That is, I think Ember.ManyArray.arrayContentDidChange may getting executed earlier than expected. If this is the case, the above mentioned code that expects the record property to already exist on all references may have been expecting this reasonably, as one of the observers directly on the content property may call DS.Store.materializeRecord on each reference. But I haven't dug deep enough to find out if this is true.
The ExamVersion class has an int? property named SourceSafeVersionNum
When I execute the following code:
var query = from examVersion in db.ExamVersions
where examVersion.ExamVersionID == ExamVersionID
select examVersion;
foreach (ExamVersion examVer in query.ToList())
{
yield return examVer;
}
examVer.SourceSafeVersionNum is set to 1 even though it is NULL in the database.
When I run the SQL code generated by LINQ in SQL Server, the SourceSafeVersionNum column value is NULL (as I'd expect) but in the foreach loop the examVer.SourceSafeVersionNum is 1.
I can't find anywhere in the code where a default value is assigned or any similar logic.
Any ideas why/where this value is being set to 1?
Here is the property declaration (generated by a .dbml file)
[Column(Storage="_SourceSafeVersionNum", DbType="Int", UpdateCheck=UpdateCheck.Never)]
public System.Nullable<int> SourceSafeVersionNum
{
get
{
return this._SourceSafeVersionNum;
}
set
{
if ((this._SourceSafeVersionNum != value))
{
this.OnSourceSafeVersionNumChanging(value);
this.SendPropertyChanging();
this._SourceSafeVersionNum = value;
this.SendPropertyChanged("SourceSafeVersionNum");
this.OnSourceSafeVersionNumChanged();
}
}
}
Have you tried setting a breakpoint in the set{} method of the property to see what else might be populating its value? You might catch the culprit in the act, then look at the Call Stack to see who it is.
As a follow up to this, here is what happened:
The code that retrieved the value from the database was being called twice but through two different code paths. The code path that was assigning the value of 1 was being stepped over by the debugger so I didn't see it.
I'm new to NHibernate and was assigned to a task where I have to change a value of an entity property and then compare if this new value (cached) is different from the actual value stored on the DB. However, every attempt to retrieve this value from the DB resulted in the cached value. As I said, I'm new to NHibernate, maybe this is something easy to do and obviously could be done with plain ADO.NET, but the client demands that we use NHibernate for every access to the DB. In order to make things clearer, those were my "successful" attempts (ie, no errors):
1
DetachedCriteria criteria = DetachedCriteria.For<User>()
.SetProjection(Projections.Distinct(Projections.Property(UserField.JobLoad)))
.Add(Expression.Eq(UserField.Id, userid));
return GetByDetachedCriteria(criteria)[0].Id; //this is the value I want
2
var JobLoadId = DetachedCriteria.For<User>()
.SetProjection(Projections.Distinct(Projections.Property(UserField.JobLoad)))
.Add(Expression.Eq(UserField.Id, userid));
ICriteria criteria = JobLoadId.GetExecutableCriteria(NHibernateSession);
var ids = criteria.List();
return ((JobLoad)ids[0]).Id;
Hope I made myself clear, sometimes is hard to explain a problem when even you don't quite understand the underlying framework.
Edit: Of course, this is a method body.
Edit 2: I found out that it doesn't work properly for the method call is inside a transaction context. If I remove the transaction, it works fine, but I need it to be in this context.
I do that opening a new stateless session for geting the actual object in the database:
User databaseuser;
using (IStatelessSession session = SessionFactory.OpenStatelessSession())
{
databaseuser = db.get<User>("id");
}
//do your checks
Within a session, NHibernate will return the same object from its Level-1 Cache (aka Identity Map). If you need to see the current value in the database, you can open a new session and load the object in that session.
I would do it like this:
public class MyObject : Entity
{
private readonly string myField;
public string MyProperty
{
get { return myField; }
set
{
if (value != myField)
{
myField = value;
DoWhateverYouNeedToDoWhenItIsChanged();
}
}
}
}
googles nhforge
http://nhibernate.info/doc/howto/various/finding-dirty-properties-in-nhibernate.html
This may be able to help you.