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  • T-SQL: Build Nested Set From Parent-Child Relationship

    - by Peder Rice
    I have a table that stores my Customer hierarchy with a nested set (due to the specific design of the application, I wasn't able to leverage just a Customer/Parent Customer mapping table). To simplify maintenance of this table, I've built a couple of stored procedures to handle moving nodes around and creating new nodes, but it's significantly more work than maintaining a Customer/Parent Customer table. Further, these structures are very fragile. So I'm looking for a way to have a Customer/Parent Customer table and then convert that table to a nested set on demand. Does anyone have a link to such an implementation?

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  • PHP object parent/child recursion

    - by Damien
    I've got a parent-child OO relationship. Parent obejcts has many child objects and every child object knows about it's parent by reference. The parent can be a child too (basically its a tree). When i do a var_dump() on the root object it says ["parent"]=RECURSION many times and the generated description will be really long. I'm wondering if i do something wrong. If yes, i'm interested in the "best practice". Thanks for the help!

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  • Complex SQL query, one to many relationship

    - by Ethan
    Hey SO, I have a query such that I need to get A specific dog All comments relating to that dog The user who posted each comment All links to images of the dog the user who posted each link I've tried a several things, and can't figure out quite how to work it. Here's what I have (condensed so you don't have to wade through it all): SELECT s.dog_id, s.name, c.comment, c.date_added AS comment_date_added, u.username AS comment_username, u.user_id AS comment_user_id, l.link AS link, l.date_added AS link_date_added, u2.username AS link_username, u2.user_id AS link_user_id FROM dogs AS d LEFT JOIN comments AS c ON c.dog_id = d.dog_id LEFT JOIN users AS u ON c.user_id = u.user_id LEFT JOIN links AS l ON l.dog_id = d.dog_id LEFT JOIN users AS u2 ON l.user_id = u2.user_id WHERE d.dog_id = '1' It's sorta close to working, but it'll only return me the first comment, and the first link all as one big array with all the info i requested. The are multiple comments and links per dog, so I need it to give me all the comments and all the links. Ideally it'd return an object with dog_id, name, comments(an array of the comments), links(an array of the links) and then comments would have a bunch of comments, date_added, username, and user_id and links would have a bunch of links with link, date_added, username and user_id. It's got to work even if there are no links or comments. I learned the basics of mySQL somewhat recently, but this is pretty far over my head. Any help would be wonderful. Thanks!

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  • NHibernate Session Load vs Get when using Table per Hierarchy. Always use ISession.Get&lt;T&gt; for TPH to work.

    - by Rohit Gupta
    Originally posted on: http://geekswithblogs.net/rgupta/archive/2014/06/01/nhibernate-session-load-vs-get-when-using-table-per-hierarchy.aspxNHibernate ISession has two methods on it : Load and Get. Load allows the entity to be loaded lazily, meaning the actual call to the database is made only when properties on the entity being loaded is first accessed. Additionally, if the entity has already been loaded into NHibernate Cache, then the entity is loaded directly from the cache instead of querying the underlying database. ISession.Get<T> instead makes the call to the database, every time it is invoked. With this background, it is obvious that we would prefer ISession.Load<T> over ISession.Get<T> most of the times for performance reasons to avoid making the expensive call to the database. let us consider the impact of using ISession.Load<T> when we are using the Table per Hierarchy implementation of NHibernate. Thus we have base class/ table Animal, there is a derived class named Snake with the Discriminator column being Type which in this case is “Snake”. If we load This Snake entity using the Repository for Animal, we would have a entity loaded, as shown below: public T GetByKey(object key, bool lazy = false) { if (lazy) return CurrentSession.Load<T>(key); return CurrentSession.Get<T>(key); } var tRepo = new NHibernateReadWriteRepository<TPHAnimal>(); var animal = tRepo.GetByKey(new Guid("602DAB56-D1BD-4ECC-B4BB-1C14BF87F47B"), true); var snake = animal as Snake; snake is null As you can see that the animal entity retrieved from the database cannot be cast to Snake even though the entity is actually a snake. The reason being ISession.Load prevents the entity to be cast to Snake and will throw the following exception: System.InvalidCastException :  Message=Unable to cast object of type 'TPHAnimalProxy' to type 'NHibernateChecker.Model.Snake'. Thus we can see that if we lazy load the entity using ISession.Load<TPHAnimal> then we get a TPHAnimalProxy and not a snake. =============================================================== However if do not lazy load the same cast works perfectly fine, this is since we are loading the entity from database and the entity being loaded is not a proxy. Thus the following code does not throw any exceptions, infact the snake variable is not null: var tRepo = new NHibernateReadWriteRepository<TPHAnimal>(); var animal = tRepo.GetByKey(new Guid("602DAB56-D1BD-4ECC-B4BB-1C14BF87F47B"), false); var snake = animal as Snake; if (snake == null) { var snake22 = (Snake) animal; }

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  • Get all related products based on their full-text search relationship

    - by MikeJ
    I have a Product table with the fields Id, Title, Description, Keywords (just comma separated list of keywords). Table is full-text indexed. When I view one product, I do a query and search the full-text catalog for any related products based on the Keywords field. select * from Products where Contains(Products.*, @keywordsFromOneProduct) Works like a charm. Now I would like to list all products and all their related products in a big list and I want to avoid calling this method for each item. Any ideas how could I do it? I was thinking about a job that would go through products one by one and build a one-many mapping table (fields ProductId, RelatedProductId), but I wonder is there a better way?

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  • IQueryable and lazy loading

    - by Nelson
    I'm having a hard time determining the best way to handle this... With Entity Framework (and L2S), LINQ queries return IQueryable. I have read various opinions on whether the DAL/BLL should return IQueryable, IEnumerable or IList. Assuming we go with IList, then the query is run immediately and that control is not passed on to the next layer. This makes it easier to unit test, etc. You lose the ability to refine the query at higher levels, but you could simply create another method that allows you to refine the query and still return IList. And there are many more pros/cons. So far so good. Now comes Entity Framework and lazy loading. I am using POCO objects with proxies in .NET 4/VS 2010. In the presentation layer I do: foreach (Order order in bll.GetOrders()) { foreach (OrderLine orderLine in order.OrderLines) { // Do something } } In this case, GetOrders() returns IList so it executes immediately before returning to the PL. But in the next foreach, you have lazy loading which executes multiple SQL queries as it gets all the OrderLines. So basically, the PL is running SQL queries "on demand" in the wrong layer. Is there any sensible way to avoid this? I could turn lazy loading off, but then what's the point of having this "feature" that everyone was complaining EF1 didn't have? And I'll admit it is very useful in many scenarios. So I see several options: Somehow remove all associations in the entities and add methods to return them. This goes against the default EF behavior/code generation and makes it harder to do some composite (multiple entity) LINQ queries. It seems like a step backwards. I vote no. If we have lazy loading anyway which makes it hard to unit test, then go all the way and return IQueryable. You'll have more control farther up the layers. I still don't think this is a good option because IQueryable ties you to L2S, L2E, or your own full implementation of IQueryable. Lazy loading may run queries "on demand", but doesn't tie you to any specific interface. I vote no. Turn off lazy loading. You'll have to handle your associations manually. This could be with eager loading's .Include(). I vote yes in some specific cases. Keep IList and lazy loading. I vote yes in many cases, only due to the troubles with the others. Any other options or suggestions? I haven't found an option that really convinces me.

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  • Edit the opposite side of a many to many relationship with django generic form

    - by Ed
    I have two models: class Actor(models.Model): name = models.CharField(max_length=30, unique = True) event = models.ManyToManyField(Event, blank=True, null=True) class Event(models.Model): name = models.CharField(max_length=30, unique = True) long_description = models.TextField(blank=True, null=True) In a previous question: http://stackoverflow.com/questions/2503243/django-form-linking-2-models-by-many-to-many-field, I created an EventForm with a save function: class EventForm(forms.ModelForm): class Meta: model = Event def save(self, commit=True): instance = forms.ModelForm.save(self) instance.actors_set.clear() for actor in self.cleaned_data['actors']: instance.actors_set.add(actors) return instance This allowed me to add m2m links from the other side of the defined m2m connection. Now I want to edit the entry. I've been using a generic function: def generic_edit(request, modelname, object_id): modelname = modelname.lower() form_class = form_dict[modelname] return update_object(request, form_class = form_class, object_id = object_id, template_name = 'createdit.html' ) but this pulls in all the info except the many-to-many selections saved to this object. I think I need to do something similar to this: http://stackoverflow.com/questions/1700202/editing-both-sides-of-m2m-in-admin-page, but I haven't figured it out. How do I use the generic update_object to edit the other side of many-to-many link?

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  • Managing EntityConnection lifetime

    - by kervin
    There have been many question on managing EntityContext lifetime, e.g. http://stackoverflow.com/questions/813457/instantiating-a-context-in-linq-to-entities I've come to the conclusion that the entity context should be considered a unit-of-work and therefore not reused. Great. But while doing some research for speeding up my database access, I ran into this blog post... Improving Entity Framework Performance The post argues that EFs poor performance compared to other frameworks is often due to the EntityConnection object being created each time a new EntityContext object is needed. To test this I manually created a static EntityConnection in Global.asax.cs Application_Start(). I then converted all my context using statements to using( MyObjContext currContext = new MyObjeContext(globalStaticEFConnection) { .... } This seems to have sped things up a bit without any errors so far as far as I can tell. But is this safe? Does using a applicationwide static EntityConnection introduce race conditions? Best regards, Kervin

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  • Parent child class relationship design pattern

    - by Jeremy
    I have a class which has a list of child items. Is there a design pattern I can copy that I can apply to these classes so that I can access the parent instance from the child, and it enforces rules such as not being able to add the child to multiple parents, etc?

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  • I would like to make a field part of a many to many relationship

    - by jona
    I have the following table called stores id store zip 1 Market 1 01569 2 Market 2 01551 3 Market 3 10468 4 Market 4 10435 Zip code table INSERT INTO `zip_codes` (`restaurants_locations_id`, `zip`, `state`, `latitude`, `longitude`, `city`, `full_state`) VALUES (1, '06001', 'CT', ' 41.789698', ' -72.86431', 'Avon', 'Connecticut'), (2, '06002', 'CT', ' 41.832798', ' -72.72642', 'Bloomfield', 'Connecticut'), (3, '06010', 'CT', ' 41.682249', ' -72.93365', 'Bristol', 'Connecticut'), (4, '06013', 'CT', ' 41.758415', ' -72.94642', 'Burlington', 'Connecticut'), (5, '06016', 'CT', ' 41.909097', ' -72.54393', 'Windsorville', 'Connecticut'), (6, '06018', 'CT', ' 42.023510', ' -73.31103', 'Canaan', 'Connecticut'), (7, '06019', 'CT', ' 41.834247', ' -72.89174', 'Canton', 'Connecticut'), etc.... what I want is to create a table which will connect the zip field in the stores tables where one store will be found in several zicodes... How would that table would look like? Thanks

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  • Classes to Entities; Like-class inheritence problems

    - by Stacey
    Beyond work, some friends and I are trying to build a game of sorts; The way we structure some of it works pretty well for a normal object oriented approach, but as most developers will attest this does not always translate itself well into a database persistent approach. This is not the absolute layout of what we have, it is just a sample model given for sake of representation. The whole project is being done in C# 4.0, and we have every intention of using Entity Framework 4.0 (unless Fluent nHibernate can really offer us something we outright cannot do in EF). One of the problems we keep running across is inheriting things in database models. Using the Entity Framework designer, I can draw the same code I have below; but I'm sure it is pretty obvious that it doesn't work like it is expected to. To clarify a little bit; 'Items' have bonuses, which can be of anything. Therefore, every part of the game must derive from something similar so that no matter what is 'changed' it is all at a basic enough level to be hooked into. Sounds fairly simple and straightforward, right? So then, we inherit everything that pertains to the game from 'Unit'. Weights, Measures, Random (think like dice, maybe?), and there will be other such entities. Some of them are similar, but in code they will each react differently. We're having a really big problem with abstracting this kind of thing into a database model. Without 'Enum' support, it is proving difficult to translate into multiple tables that still share a common listing. One solution we've depicted is to use a 'key ring' type approach, where everything that attaches to a character is stored on a 'Ring' with a 'Key', where each Key has a Value that represents a type. This works functionally but we've discovered it becomes very sluggish and performs poorly. We also dislike this approach because it begins to feel as if everything is 'dumped' into one class; which makes management and logical structure difficult to adhere to. I was hoping someone else might have some ideas on what I could do with this problem. It's really driving me up the wall; To summarize; the goal is to build a type (Unit) that can be used as a base type (Table per Type) for generic reference across a relatively global scope, without having to dump everything into a single collection. I can use an Interface to determine actual behavior so that isn't too big of an issue. This is 'roughly' the same idea expressed in the Entity Framework.

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  • What is the relationship between domNode and htmlelement?

    - by Turtle
    Hello, I am confused about the two terms. What is the difference in browser-side javascript programming? I use dojo as framework. And there is only the concept of domNode. But browser debugger always told me something as htmlelement. Are they just the same thing with different names, or with some subtle differences? Thanks.

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  • java: relationship of the Runnable and Thread interfaces

    - by Karl Patrick
    I realize that the method run() must be declared because its declared in the Runnable interface. But my question comes when this class runs how is the Thread object allowed if there is no import call to a particular package? how does runnable know anything about Thread or its methods? does the Runnable interface extend the Thread class? Obviously I don't understand interfaces very well. thanks in advance. class PrimeFinder implements Runnable{ public long target; public long prime; public boolean finished = false; public Thread runner; PrimeFinder(long inTarget){ target = inTarget; if(runner == null){ runner = new Thread(this); runner.start() } } public void run(){ } }

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  • getting hasMany records of a HABTM relationship

    - by charliefarley321
    I have tables: categories HABTM sculptures hasMany images from the CategoriesController#find() produces an array like so: array( 'Category' => array( 'id' => '3', 'name' => 'Modern', ), 'Sculpture' => array( (int) 0 => array( 'id' => '25', 'name' => 'Ami', 'material' => 'Bronze', 'CategoriesSculpture' => array( 'id' => '18', 'category_id' => '3', 'sculpture_id' => '25' ) ), (int) 1 => array( 'id' => '26', 'name' => 'Charis', 'material' => 'Bronze', 'CategoriesSculpture' => array( 'id' => '19', 'category_id' => '3', 'sculpture_id' => '26' ) ) ) ) I'd like to be able to get the images related to sculpture in the array as well if this is possible?

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  • JDO in Google App Engine: order of keys in unowned one-to-many relationship

    - by Kel
    I'm implementing web application with JDO in Google App Engine. According to documentation, in owned one-to-many relationships, order of elements in "owner" object collection is determined either by automatically created index field, or by information given in explicit ordering clause. For example: @PersistenceCapable public class Person { // ... @Order(extensions = @Extension(vendorName="datanucleus", key="list-ordering", value="country asc, city asc")) private List<ContactInfo> contacts = new List<ContactInfo>(); In unowned relationships, "owner" object contains collection of keys of "nested" objects, for example: @PersistenceCapable public class Author { // ... @Persistent private List<Key> books; Is order of keys preserved, if I use List<Key> collection in "owner" object for storing keys of "nested" elements? I could not find answer neither in JDO relationships article, nor in Data Classes article :(

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  • Bound a treeview control to user-defined complex type using EF 4

    - by GIbboK
    Hi, I use Asp.net, SQL 2008 and EF 4. I need display hierarchy data in a treeview control, Data is stored in a DB that use HierarchyId. Unfortunately, EF4 doesn't support HierarchyId. So in this case, I thought to have a stored procedure that deals with my hierarchy and return a result set back to EF that EF4 can turn into a collection of user-defined complex type that can then be bound directly to the treeview control. I imported a SPROC in EF 4 using Import Function and now I have a Complex DataType called: CategoryHierarchy_Result An image of my Model: Here some data from the Complex Type (in a GridView for example GridView1.DataSource = context.CategoryHierarchy(1);): My questions is: How to display my data from my Complex Type in a TreeView Control, showing a Tree structure that respect CategoryNodeString? I am a beginner an I never use TreeView before, any help or resource would be appreciated! Thanks!. Here some useful resource: http://www.robbagby.com/entity-framework/entity-framework-modeling-action-stored-procedures/

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  • 'Locale' configuration and its relationship with Windows API

    - by The Kaykay
    Can the locale configuration of a system OR the keyboard type configuration of that system in anyway affect which API is called at the Kernel level? To be specific, if a program is invoking 'CreateFile()' API then the windows API documentation says that the call gets delegated to either CreateFileA or CreateFileW. If that program is being run on a system present in China with a Chinese Keyboard then which of the two functions will be called?

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  • How to model a mutually exclusive relationship in sql server

    - by littlechris
    Hi, I have to add functionality to an existing application and I've run into a data situation that I'm not sure how to model. I am being restricted to the creation of new tables and code. If I need to alter the existing structure I think my client may reject the proposal..although if its the only way to get it right this is what I will have to do. I have an Item table that can me link to any number of tables, and these tables may increase over time. The Item can only me linked to one other table, but the record in the other table may have many items linked to it. Examples of the tables/entities being linked to are "Person", "Vehicle", "Building", "Office". These are all separate tables. Example of Items are "Pen", "Stapler", "Cushion", "Tyre", "A4 Paper", "Plastic Bag", "Poster", "Decoration" For instance a "Poster" may be allocated to a "Person" or "Office" or "Building". In the future if they add a "Conference Room" table it may also be added to that. My intital thoughts are: Item { ID, Name } LinkedItem { ItemID, LinkedToTableName, LinkedToID } The LinkedToTableName field will then allow me to identify the correct table to link to in my code. I'm not overly happy with this solution, but I can't quite think of anything else. Please help! :) Thanks!

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  • Error in Using Dynamic Data Entities WebSite in VS2012

    - by amin behzadi
    I decided to use Dynamic Data Entities website in vs2012. So, I created this website,then added App_Code directory and added a new edmx to it and named it myDB.edmx. After that I uncommented the code line in global.asax which registers the entity context : DefaultModel.RegisterContext(typeof(myDBEntities), new ContextConfiguration() { ScaffoldAllTables = true }); But when I run the website this error occurs : The context type 'myDBEntities' is not supported. how can I fix it? p.s: You now there are some differences between using L2S by Dynamic Data L2S website AND using entity framework by Dynamic Data Entities website.

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  • Same data being returned by linq for 2 different executions of a stored procedure?

    - by Paul
    Hello I have a stored procedure that I am calling through Entity Framework. The stored procedure has 2 date parameters. I supply different argument in the 2 times I call the stored procedure. I have verified using SQL Profiler that the stored procedure is being called correctly and returning the correct results. When I call my method the second time with different arguments, even though the stored procedure is bringing back the correct results, the table created contains the same data as the first time I called it. dtStart = 01/08/2009 dtEnd = 31/08/2009 public List<dataRecord> GetData(DateTime dtStart, DateTime dtEnd) { var tbl = from t in db.SP(dtStart, dtEnd) select t; return tbl.ToList(); } GetData((new DateTime(2009, 8, 1), new DateTime(2009, 8, 31)) // tbl.field1 value = 45450 - CORRECT GetData(new DateTime(2009, 7, 1), new DateTime(2009, 7, 31)) // tbl.field1 value = 45450 - WRONG 27456 expected Is this a case of Entity Framework being clever and caching? I can't see why it would cache this though as it has executed the stored procedure twice. Do I have to do something to close tbl? using Visual Studio 2008 + Entity Framework. I also get the message "query cannot be enumerated more than once" a few times every now and then, am not sure if that is relevant? FULL CODE LISTING namespace ProfileDataService { public partial class DataService { public static List<MeterTotalConsumpRecord> GetTotalAllTimesConsumption(DateTime dtStart, DateTime dtEnd, EUtilityGroup ug, int nMeterSelectionType, int nCustomerID, int nUserID, string strSelection, bool bClosedLocations, bool bDisposedLocations) { dbChildDataContext db = DBManager.ChildDataConext(nCustomerID); var tbl = from t in db.GetTotalConsumptionByMeter(dtStart, dtEnd, (int) ug, nMeterSelectionType, nCustomerID, nUserID, strSelection, bClosedLocations, bDisposedLocations, 1) select t; return tbl.ToList(); } } } /// CALLER List<MeterTotalConsumpRecord> _P1Totals; List<MeterTotalConsumpRecord> _P2Totals; public void LoadData(int nUserID, int nCustomerID, ELocationSelectionMethod locationSelectionMethod, string strLocations, bool bIncludeClosedLocations, bool bIncludeDisposedLocations, DateTime dtStart, DateTime dtEnd, ReportsBusinessLogic.Lists.EPeriodType durMainPeriodType, ReportsBusinessLogic.Lists.EPeriodType durCompareToPeriodType, ReportsBusinessLogic.Lists.EIncreaseReportType rptType, bool bIncludeDecreases) { ///Code for setting properties using parameters.. _P2Totals = ProfileDataService.DataService.GetTotalAllTimesConsumption(_P2StartDate, _P2EndDate, EUtilityGroup.Electricity, 1, nCustomerID, nUserID, strLocations, bIncludeClosedLocations, bIncludeDisposedLocations); _P1Totals = ProfileDataService.DataService.GetTotalAllTimesConsumption(_StartDate, _EndDate, EUtilityGroup.Electricity, 1, nCustomerID, nUserID, strLocations, bIncludeClosedLocations, bIncludeDisposedLocations); PopulateLines() //This fills up a list of objects with information for my report ready for the totals to be added PopulateTotals(_P1Totals, 1); PopulateTotals(_P2Totals, 2); } void PopulateTotals(List<MeterTotalConsumpRecord> objTotals, int nPeriod) { MeterTotalConsumpRecord objMeterConsumption = null; foreach (IncreaseReportDataRecord objLine in _Lines) { objMeterConsumption = objTotals.Find(delegate(MeterTotalConsumpRecord t) { return t.MeterID == objLine.MeterID; }); if (objMeterConsumption != null) { if (nPeriod == 1) { objLine.P1Consumption = (double)objMeterConsumption.Consumption; } else { objLine.P2Consumption = (double)objMeterConsumption.Consumption; } objMeterConsumption = null; } } } }

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  • CakePHP hasMany relationship with multiple columns

    - by Muhammad Yasir
    Hi, I am using CakePHP framework to build a web application. The simplest form of my problem is this: I have a users table and a messages table with corresponding models. Messages are sent from a user to another user. So messages table has columns from_id and to_id in it, both referencing to id of users. I am able to link Message model to User model by using $belongsTo but I am unable to link User model with Message model (in reverse direction) by using $hasMany in the same manner. var $hasMany = array( 'From' => array( 'className' => 'Message', 'foreignKey' => 'from_id', 'dependent' => false, 'conditions' => '', 'fields' => '', 'order' => '', 'limit' => '', 'offset' => '', 'exclusive' => '', 'finderQuery' => '', 'counterQuery' => '' ), 'To' => array( 'className' => 'Message', 'foreignKey' => 'to_id', 'dependent' => false, 'conditions' => '', 'fields' => '', 'order' => '', 'limit' => '', 'offset' => '', 'exclusive' => '', 'finderQuery' => '', 'counterQuery' => '' ) ); What can do here? Any ideas? Thanks for any help.

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  • Inverse relationship of two variables

    - by Jam
    this one is maybe pretty stupid.. Or I am just exhausted or something, but I just cant seem to solve it.. Problem : two variables X and Y, value of Y is dependent on value of X. X can have values ranging from some value to some value (lets say from 0 to 250) and y can have different values (lets say from 0.1 to 1.0 or something..) - but it is inverse relatonship (what I mean is: if value of X is e.g. 250, then value of Y would be 0.1 and when X decreases up to 0, value of Y raises up to 1.0.. So how should I do it? lets say I have function: -- double computeValue (double X) { /computation/ return Y; } Also, is there some easy way to somehow make the scaling of the function not so linear? - For example when X raises, Y decreases slower at first but then more rapidly in the end.. (rly dont know how to say it but I hope you guys got it) Thanks in advance for this stupid question :/

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  • Exception while trying to deserialize JSON into EntityFramework using JavaScriptSerializer

    - by Barak
    I'm trying to deserialize JSON which I'm getting from an external source into an Entity Framework entity class using the following code: var serializer = new JavaScriptSerializer(); IList<Feature> obj = serializer.Deserialize<IList<Feature>>(json); The following exception is thrown: Object of type 'System.Collections.Generic.List1[JustTime.Task]' cannot be converted to type 'System.Data.Objects.DataClasses.EntityCollection1[JustTime.Task]'. My model is simple: The Feature class has a one-to-many relation to the Tasks class. The problem appears to be the deserializer is trying to create a generic List to hold the collection of tasks instead of an EntityCollection. I've tried implementing a JavaScriptConverted which would handle System.Collections.Generic.List but it didn't get called by the deserializer.

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  • Preventing EF4 ConstraintException when invoking TryUpdateModel

    - by twk
    Given following ASP.NET MVC controller code: [HttpPost] public ActionResult Create(FormCollection collection) { string[] whitelist = new []{ "CompanyName", "Address1", "Address2", ... }; Partner newPartner = new Partner(); if (TryUpdateModel(newPartner, whitelist, collection)) { var db = new mainEntities(); db.Partners.AddObject(newPartner); db.SaveChanges(); return RedirectToAction("Details/" + newPartner.ID); } else { return View(); } } The problem is with the Entity Framework 4: the example Partner entity is mapped to a database table with it's fields NOT ALLOWED to be NULL (which is ok by design - they're required). Unfortunately, invoking TryUpdateModel when some of the properties are nulls produces ConstraintException which is not expected! I do expect that TryUpdateModel return false in this case. It is ok that EF wouldn't allow set a property value to null if it should not be, but the TryUpdateMethod should handle that, and add the error to ModelState errors collection. I am wrong, or somebody screwed the implementation of TryUpdateModel method?

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