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• Best practices for sending automated daily emails from web service

  - by Tauren

  I am running a web service that currently sends confirmation emails out to new users via the gmail smtp servers. As I'm only getting a few new users each day, this hasn't been a problem. I've recently added new features to the webapp that will require a customized message to be sent out to each user every day. Think of this as similar to the regular messages LinkedIn sends out that give you a status report on the activity in your network. Every user's message will be different. With thousands of users, this means thousands of unique messages will be sent each day. Edit: I've since found that these types of email are called "transactional or relationship messages". Spamtacular has a good article on differentiating between marketing and transactional email. I don't think using gmail's smtp servers will cut it anymore, but I don't know that for sure. I don't know what gmail's maximum outgoing messages per account is (it might be 100/day), but they limit outgoing mail to 500 recipients per message. I'm not sending a single message to 500 recipients, but I'm going to be sending 1000's of customized messages with each recipient getting one per day. I'm interested to learn any best practices for doing this (especially for Java-based webapps). Here are some of my thoughts and concerns on it: Should I set up my own outgoing mail server? If I do this, it seems like I'll have all sorts of other issues to worry about, such as preventing mail server abuse, monitoring bounces, allowing ways to opt-out of emails, etc. Are there any tools or services to help with this? Maybe something like OpenEMM or a services like MailChimp? But those seem focused more toward email marketing campaigns. I don't think I should have the webapp itself handle sending emails as it currently is for new user signups. I'm thinking I should setup a separate messaging server that can access the same backend/datastore as the webapp. Thoughts on this? Should I consider setting up some sort of message queueing service to help with this, such as JMS, RabbitMQ, ActiveMQ, etc.? Do I need to provide users a way to opt-out? Do I need to flag these as bulk messages? I don't really consider these email marketing messages, but I'm unsure what is considered appropriate or proper netiquette. Any advice is appreciated. I'm also very interested in open source tools or web services that simplify things and could help me to ramp up as quickly as possible. Thanks!

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• Nhibernate One-to-one mapping issue with child object insert error

  - by TalkDotNet

  Hi, i've being banging my head against the desk all day with the following Nhibernate problem. Each bank account has one (and only one) set of rates associated with it. The primary key of the bank account table, BankAccountID is also a foreign key and the primary key in the rates table. public class BankAccount { public virtual int BankAccountId { get; set; } public virtual string AccountName { get; set;} public virtual AccountRate AccountRate {get;set;} } public class AccountRate { public virtual int BankAccountId { get; set; } public virtual decimal Rate1 { get; set; } public virtual decimal Rate2 { get; set; } } I have the following HBM mappings for BankAccount: <class name="BankAccount" table="BankAccount"> <id name ="BankAccountId" column="BankAccountId"> <generator class="foreign"> <param name="property"> AccountRate </param> </generator> </id> <property name ="AccountName" column="AccountName" /> <one-to-one name="AccountRate" class="AccountRate" constrained="true" cascade="save-update"/> </class> and the following for AccountRate: <class name="AccountRate" table="AccountRate"> <id name ="BankAccountId" column="BankAccountId"> <generator class="native" /> </id> <property name ="Rate1" column="Rate1" /> <property name ="Rate2" column="Rate2" /> </class> An existing BankAccount object can be read from the database with no problem. However, when a new BankAccount is created , the insert statement fails with; Cannot insert the value NULL into column 'BankAccountId' The issue appears to be that the child object , AccountRate is created first and since it hasn't yet got an identifier from its uncreated parent , the insert fails. I think i'm correct in saying that if the AccountRate property on BankAccount was a collection i could use the following ? Inverse=True in order to force the parent to be inserted first. Can anyone help me with this? i Really dont want to use a collection as there is only a unidirectional one to one relationship between these tables. Thanks Paul

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• Crazy VS Designer Errors

  - by BlueRaja

  Here's a strange one. After renaming a class, one of my forms began giving me errors in the designer, refusing to open. Funny thing is, the form worked just fine when I ran the program. I began reverting my changes to deduce the problem. I have now reverted completely back to the last commit - in which I know the form was working in the designer - cleaned the solution, and deleted the bin/ and obj/ folders, as well as the *.suo file for good measure. The form still does not display in designer. Here are the errors it gives: Could not find 'MyNamespace.MyControl'. Please make sure that the assembly that contains this type is referenced. If this type is a part of your development project, make sure that the project has been successfully built. The variable 'myControl1' is either undeclared or was never assigned. The variable is both declared and assigned, and MyControl builds fine (again, the form works fine when the program is actually run). Stranger still, if I try to create a new form and drag a MyControl onto it, I get this Entity-Framework error: Failed to create component 'MyControl'. The error message follows: 'System.ArgumentException: The specified named connection is either not found in the configuration, not intended to be used with the EntityClient provider, or not valid. at System.Data.EntityClient.EntityConnection.ChangeConnectionString(String newConnectionString) at System.Data.EntityClient.EntityConnection..ctor(String connectionString) at System.Data.Objects.ObjectContect.CreateEntityConnection(String connectionString) etc. etc. There is nothing wrong with my connection string: it worked before, and, again, it works when I actually run the program (the control already exists on the old form from the previous commit). Any ideas whatsoever? I am completely at a loss. [Edit] The only significant code: MyControl.cs public MyControl() { _entities = new MyEFEntities(); //Entity-framework generated class } MyForm.Designer.cs private void InitializeComponent() { this.myControl1 = new MyNamespace.MyControl(); ... this.Controls.Add(this.myControl1); } MyEFDatabase.Designer.cs public MyEFEntities() : base("name=MyEFEntities", "MyEFEntities") { ... } App.Config <connectionStrings> <add name="MyEFEntities" connectionString="metadata=res://*/MyEFDatabase.csdl|res://*/MyEFDatabase.ssdl|res://*/MyEFDatabase.msl;provider=System.Data.SqlClient;provider connection string=&quot;Data Source=MyDatabaseServer;Initial Catalog=MyDatabase;Integrated Security=True;MultipleActiveResultSets=True&quot;" providerName="System.Data.EntityClient" /> </connectionStrings> I've tried the "replace &quot; with '" trick - didn't help. [Edit2] It is happening to new projects also, but not immediately. Only after fiddling around a bit (it has something to do with adding a many-to-one relationship that EF did not figure out on its own), but I can't figure out the exact steps to reproduce.

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• Fluent NHibernate Self Referencing Many To Many

  - by Jeremy

  I have an entity called Books that can have a list of more books called RelatedBooks. The abbreviated Book entity looks something likes this: public class Book { public virtual long Id { get; private set; } public virtual IList<Book> RelatedBooks { get; set; } } Here is what the mapping looks like for this relationship HasManyToMany(x => x.RelatedBooks) .ParentKeyColumn("BookId") .ChildKeyColumn("RelatedBookId") .Table("RelatedBooks") .Cascade.SaveUpdate(); Here is a sample of the data that is then generated in the RelatedBooks table: BookId RelatedBookId 1 2 1 3 The problem happens when I Try to delete a book. If I delete the book that has an ID of 1, everything works ok and the RelatedBooks table has the two corresponding records removed. However if I try to delete the book with an ID of 3, I get the error "The DELETE statement conflicted with the REFERENCE constraint "FK5B54405174BAB605". The conflict occurred in database "Test", table "dbo.RelatedBooks", column 'RelatedBookId'". Basically what is happening is the Book cannot be deleted because the record in the RelatedBooks table that has a RelatedBookId of 3 is never deleted. How do I get that record to be deleted when I delete a book? EDIT After changing the Cascade from SaveUpdate() to All(), the same problem still exists if I try to delete the Book with an ID of 3. Also with Cascade set to All(), if delete the Book with and ID of 1, then all 3 books (ID's: 1, 2 and 3) are deleted so that won't work either. Looking at the SQL that is executed when the Book.Delete() method is called when I delete the Book with an ID of 3, it looks like the SELECT statement is looking at the wrong column (which I assume means that the SQL DELETE statment would make the same mistake, therefore never removing that record). Here is the SQL for the RelatedBook SELECT relatedboo0_.BookId as BookId3_ , relatedboo0_.RelatedBookId as RelatedB2_3_ , book1_.Id as Id14_0_ FROM RelatedBooks relatedboo0_ left outer join [Book] book1_ on relatedboo0_.RelatedBookId=book1_.Id WHERE relatedboo0_.BookId=3 The WHERE statment should look something like this for thie particular case: WHERE relatedboo0_.RelatedBookId = 3 SOLUTION Here is what I had to do to get it working for all cases Mapping: HasManyToMany(x => x.RelatedBooks) .ParentKeyColumn("BookId") .ChildKeyColumn("RelatedBookId") .Table("RelatedBooks"); Code: var book = currentSession.Get<Book>(bookId); if (book != null) { //Remove all of the Related Books book.RelatedBooks.Clear(); //Get all other books that have this book as a related book var booksWithRelated = currentSession.CreateCriteria<Book>() .CreateAlias("RelatedBooks", "br") .Add(Restrictions.Eq("br.Id", book.Id)) .List<Book>(); //Remove this book as a Related Book for all other Books foreach (var tempBook in booksWithRelated) { tempBook.RelatedBooks.Remove(book); tempBook.Save(); } //Delete the book book.Delete(); }

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• In MySQL, what is the most effective query design for joining large tables with many to many relatio

  - by lighthouse65

  In our application, we collect data on automotive engine performance -- basically source data on engine performance based on the engine type, the vehicle running it and the engine design. Currently, the basis for new row inserts is an engine on-off period; we monitor performance variables based on a change in engine state from active to inactive and vice versa. The related engineState table looks like this: +---------+-----------+---------------+---------------------+---------------------+-----------------+ | vehicle | engine | engine_state | state_start_time | state_end_time | engine_variable | +---------+-----------+---------------+---------------------+---------------------+-----------------+ | 080025 | E01 | active | 2008-01-24 16:19:15 | 2008-01-24 16:24:45 | 720 | | 080028 | E02 | inactive | 2008-01-24 16:19:25 | 2008-01-24 16:22:17 | 304 | +---------+-----------+---------------+---------------------+---------------------+-----------------+ For a specific analysis, we would like to analyze table content based on a row granularity of minutes, rather than the current basis of active / inactive engine state. For this, we are thinking of creating a simple productionMinute table with a row for each minute in the period we are analyzing and joining the productionMinute and engineEvent tables on the date-time columns in each table. So if our period of analysis is from 2009-12-01 to 2010-02-28, we would create a new table with 129,600 rows, one for each minute of each day for that three-month period. The first few rows of the productionMinute table: +---------------------+ | production_minute | +---------------------+ | 2009-12-01 00:00 | | 2009-12-01 00:01 | | 2009-12-01 00:02 | | 2009-12-01 00:03 | +---------------------+ The join between the tables would be engineState AS es LEFT JOIN productionMinute AS pm ON es.state_start_time <= pm.production_minute AND pm.production_minute <= es.event_end_time. This join, however, brings up multiple environmental issues: The engineState table has 5 million rows and the productionMinute table has 130,000 rows When an engineState row spans more than one minute (i.e. the difference between es.state_start_time and es.state_end_time is greater than one minute), as is the case in the example above, there are multiple productionMinute table rows that join to a single engineState table row When there is more than one engine in operation during any given minute, also as per the example above, multiple engineState table rows join to a single productionMinute row In testing our logic and using only a small table extract (one day rather than 3 months, for the productionMinute table) the query takes over an hour to generate. In researching this item in order to improve performance so that it would be feasible to query three months of data, our thoughts were to create a temporary table from the engineEvent one, eliminating any table data that is not critical for the analysis, and joining the temporary table to the productionMinute table. We are also planning on experimenting with different joins -- specifically an inner join -- to see if that would improve performance. What is the best query design for joining tables with the many:many relationship between the join predicates as outlined above? What is the best join type (left / right, inner)?

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• Flex barChart and XML Data

  - by theband

  <Projectlist> <Project> <ProjectName>Alcoswitch - ToggleSwitches </ProjectName> <ProjectStatusname>Planning</ProjectStatusname> </Project> <Project> <ProjectName> Transverse Wedge</ProjectName> <ProjectStatusname>Canceled</ProjectStatusname> </Project> <Project> <ProjectName>High Speed Pluggable I/O</ProjectName> <ProjectStatusname>In-Progress</ProjectStatusname> </Project> <Project> <ProjectName>"High Speed Pluggable I/O - Product Breakouts:</ProjectName> <ProjectStatusname>In-Progress</ProjectStatusname> </Project> <Project> <ProjectName>Circular Plastic Connector (CPC)</ProjectName> <ProjectStatusname>In-Progress</ProjectStatusname> </Project> </Projectlist> This is my XML data i am recieving, how can i show this in a bar chart. <mx:BarChart id="barChart" showDataTips="true" dataProvider="{ProjectStateInfo}" width="100%" height="100%"> <mx:horizontalAxis> <mx:CategoryAxis categoryField="ProjectStatusname"/> </mx:horizontalAxis> <mx:verticalAxis> <mx:CategoryAxis categoryField="ProjectName"/> </mx:verticalAxis> <mx:series> <mx:BarSeries id="barSeries" visible="true" yField="ProjectName" xField="ProjectStatusname" displayName="ProjectStatusname" /> </mx:series> </mx:BarChart> My X-Axis shows muliple values of In-Progress, but i just need one. Is it possible to represent such relationship using BarChart. Any other Flex chart is Advisable.

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• Rails scalar query

  - by Craig

  I need to display a UI element (e.g. a star or checkmark) for employees that are 'favorites' of the current user (another employee). The Employee model has the following relationship defined to support this: has_and_belongs_to_many :favorites, :class_name => "Employee", :join_table => "favorites", :association_foreign_key => "favorite_id", :foreign_key => "employee_id" The favorites has two fields: employee_id, favorite_id. If I were to write SQL, the following query would give me the results that I want: SELECT id, account, IF( ( SELECT favorite_id FROM favorites WHERE favorite_id=p.id AND employee_id = ? ) IS NULL, FALSE, TRUE) isFavorite FROM employees Where the '?' would be replaced by the session[:user_id]. How do I represent the isFavorite scalar query in Rails? Another approach would use a query like this: SELECT id, account, IF(favorite_id IS NULL, FALSE, TRUE) isFavorite FROM employees e LEFT OUTER JOIN favorites f ON e.id=f.favorite_id AND employee_id = ? Again, the '?' is replaced by the session[:user_id] value. I've had some success writing this in Rails: ee=Employee.find(:all, :joins=>"LEFT OUTER JOIN favorites ON employees.id=favorites.favorite_id AND favorites.employee_id=1", :select=>"employees.*,favorites.favorite_id") Unfortunately, when I try to make this query 'dynamic' by replacing the '1' with a '?', I get errors. ee=Employee.find(:all, :joins=>["LEFT OUTER JOIN favorites ON employees.id=favorites.favorite_id AND favorites.employee_id=?",1], :select=>"employees.*,favorites.favorite_id") Obviously, I have the syntax wrong, but can :joins expressions be 'dynamic'? Is this a case for a Lambda expression? I do hope to add other filters to this query and use it with will_paginate and acts_as_taggable_on, if that makes a difference. edit errors from trying to make :joins dynamic: ActiveRecord::ConfigurationError: Association named 'LEFT OUTER JOIN favorites ON employees.id=favorites.favorite_id AND favorites.employee_id=?' was not found; perhaps you misspelled it? from /Users/craibuc/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/associations.rb:1906:in `build' from /Users/craibuc/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/associations.rb:1911:in `build' from /Users/craibuc/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/associations.rb:1910:in `each' from /Users/craibuc/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/associations.rb:1910:in `build' from /Users/craibuc/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/associations.rb:1830:in `initialize' from /Users/craibuc/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:1789:in `new' from /Users/craibuc/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:1789:in `add_joins!' from /Users/craibuc/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:1686:in `construct_finder_sql' from /Users/craibuc/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:1548:in `find_every' from /Users/craibuc/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:615:in `find'

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• Dynamic Linq help, different errors depending on object passed as parameter?

  - by sah302

  I have an entityDao that is inherbited by everyone of my objectDaos. I am using Dynamic Linq and trying to get some generic queries to work. I have the following code in my generic method in my EntityDao : public abstract class EntityDao<ImplementationType> where ImplementationType : Entity { public ImplementationType getOneByValueOfProperty(string getProperty, object getValue){ ImplementationType entity = null; if (getProperty != null && getValue != null) { LCFDataContext lcfdatacontext = new LCFDataContext(); //Generic LINQ Query Here entity = lcfdatacontext.GetTable<ImplementationType>().Where(getProperty + " =@0", getValue).FirstOrDefault(); //.Where(getProperty & "==" & CStr(getValue)) } //lcfdatacontext.SubmitChanges() //lcfdatacontext.Dispose() return entity; } }         Then I do the following method call in a unit test (all my objectDaos inherit entityDao): [Test] public void getOneByValueOfProperty() { Accomplishment result = accomplishmentDao.getOneByValueOfProperty("AccomplishmentType.Name", "Publication"); Assert.IsNotNull(result); } The above passes (AccomplishmentType has a relationship to accomplishment) Accomplishment result = accomplishmentDao.getOneByValueOfProperty("Description", "Can you hear me now?"); Accomplishment result = accomplishmentDao.getOneByValueOfProperty("LocalId", 4); Both of the above work Accomplishment result = accomplishmentDao.getOneByValueOfProperty("Id", New Guid("95457751-97d9-44b5-8f80-59fc2d170a4c"))       Does not work and says the following: Operator '=' incompatible with operand types 'Guid' and 'Guid Why is this happening? Guid's can't be compared? I tried == as well but same error. What's even moreso confusing is that every example of Dynamic Linq I have seen simply usings strings whether using the parameterized where predicate or this one I have commented out: //.Where(getProperty & "==" & CStr(getValue)) With or without the Cstr, many datatypes don't work with this format. I tried setting the getValue to a string instead of an object as well, but then I just get different errors (such as a multiword string would stop comparison after the first word). What am I missing to make this work with GUIDs and/or any data type? Ideally I would like to be able to just pass in a string for getValue (as I have seen for every other dynamic LINQ example) instead of the object and have it work regardless of the data Type of the column.

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• LINQ to SQL Could not find key member. Only fails on server.

  - by Adam Carr

  I have a scenario where I am inheriting from an abstract class in my partial linq to sql auto generated class implementation. My base abstract class has an abstract property called ID which I have flagged inside my LINQ to SQL model with the instance modifier override. This works fine locally without any issues. I have also done some development on another machine and it works fine there too (both in VS2008 and using Subversion). I am running CI with TeamCity and the build succeeds and deploys as desired. The problem is when the server tries to hit the database for the first time via the LINQ to SQL data context, it generates the following error. "Could not find key member 'Id' of key 'Id' on type 'CustomType'. The key may be wrong or the field or property on 'CustomType' has changed names." I have tried changing my configuration by not implementing the Id field in my base class but this still fails. Why does it work on both of my DEV machines but not on the server? I am using LINQ to SQL in another project that runs on this server just fine. FYI: LINQ to SQL, SQL 2008, .NET 3.5, SERVER 2008, IIS 7.0 UPDATE I have gone back and added the same table a second time in the same data model but without a base class and have then displayed the results from that table and got no errors. This tells me it has something to do with my base abstract class and the need to flag a property on one of my linq to sql model classes (that belongs to a key relationship) with the instance modifier of override. No answer to this yet but am getting closer. UPDATE I have fixed my issue by simply changing my approach to my problem but I am still interested in why this doesn't work. I created a new WinSrv2008 VPC and patched it, deployed a pre-built version of my site to it and still got the same error. I now assume the issue is like what the person said here, a dependency issue with VS2008. My question is what or what? Will install VS2008 on the VPC to see if it works after that.

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• Evaluating points in time by months, but without referencing years in Rails

  - by MikeH

  FYI, There is some overlap in the initial description of this question with a question I asked yesterday, but the question is different. My app has users who have seasonal products. When a user selects a product, we allow him to also select the product's season. We accomplish this by letting him select a start date and an end date for each product. We're using date_select to generate two sets of drop-downs: one for the start date and one for the end date. Including years doesn't make sense for our model. So we're using the option: discard_year => true When you use discard_year => true, Rails sets a year in the database, it just doesn't appear in the views. Rails sets all the years to either 0001 or 0002 in our app. Yes, we could make it 2009 and 2010 or any other pair. But the point is that we want the months and days to function independent of a particular year. If we used 2009 and 2010, then those dates would be wrong next year because we don't expect these records to be updated every year. My problem is that we need to dynamically evaluate the availability of products based on their relationship to the current month. For example, assume it's March 15. Regardless of the year, I need a method that can tell me that a product available from October to January is not available right now. If we were using actual years, this would be pretty easy. For example, in the products model, I can do this: def is_available? (season_start.past? && season_end.future?) end I can also evaluate a start_date and an end_date against current_date However, in setup I've described above where we have arbitrary years that only make sense relative to each other, these methods don't work. For example, is_available? would return false for all my products because their end date is in the year 0001 or 0002. What I need is a method just like the ones I used as examples above, except that they evaluate against current_month instead of current_date, and past? and future months instead of years. I have no idea how to do this or whether Rails has any built in functionality that could help. I've gone through all the date and time methods/helpers in the API docs, but I'm not seeing anything equivalent to what I'm describing. Thanks.

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• How to create Query syntax for multiple DataTable for implementing IN operator of Sql Server

  - by Shantanu Gupta

  I have fetched 3-4 tables by executing my stored procedure. Now they resides on my dataset. I have to maintain this dataset for multiple forms and I am not doing any DML operation on this dataset. Now this dataset contains 4 tables out of which i have to fetch some records to display data. Data stored in tables are in form of one to many relationship. i.e. In case of transactions. N records per record. Then these N records are further mapped to M records of 3rd table. Table 1 MAP_ID GUEST_ID DEPARTMENT_ID PARENT_ID PREFERENCE_ID -------------------- -------------------- -------------------- -------------------- -------------------- 19 61 1 1 5 14 61 1 5 15 15 61 2 4 10 18 61 2 13 23 17 61 2 20 26 16 61 40 40 41 20 62 1 5 14 21 62 1 5 15 22 62 1 6 16 24 62 2 3 4 23 62 2 4 9 27 62 2 13 23 25 62 2 20 24 26 62 2 20 25 28 63 1 1 5 29 63 1 1 8 34 63 1 5 15 30 63 2 4 10 33 63 2 4 11 31 63 2 13 23 32 63 40 40 41 35 65 1 NULL 1 36 65 1 NULL 1 38 68 2 13 22 37 68 2 20 25 39 68 2 23 27 40 92 1 NULL 1 Table 2 Department_ID Department_Name Parent_Id Parent_Name -------------------- ----------------------- --------------- ---------------------------------------------------------------------------------- 1 Food 1, 5, 6 Food, North Indian, South Indian 2 Lodging 3, 4, 13, 20, 23 Room, Floor, Non Air Conditioned, With Balcony, Without Balcony 40 New 40 SubNew TABLE 3 Parent_Id Parent_Name Preference_ID Preference_Name -------------------- ----------------------------------------------- ----------------------- ------------------- NULL NULL NULL NULL 1 Food 5, 8 North Indian, Italian 3 Room 4 Floor 4 Floor 9, 10, 11 First, Second, Third 5 North Indian 14, 15 X, Y 6 South Indian 16 Dosa 13 Non Air Conditioned 22, 23 With Balcony, Without Balcony 20 With Balcony 24, 25, 26 Mountain View, Ocean View, Garden View 23 Without Balcony 27 Mountain View 40 New 41 SubNew I have these 3 tables that are related in some fashion like this. Table 1 will be the master for these 2 tables i.e. table 2 and table 3. I need to query on them as SELECT Department_Id, Department_Name, Parent_Name FROM Table2 WHERE Department_Id in ( SELECT Department_Id FROM Table1 WHERE guest_id=65 ) SELECT Parent_Id, Parent_Name, Preference_Name FROM Table3 WHERE PARENT_ID in ( SELECT parent_id FROM Table1 WHERE guest_id=65 ) Now I need to use these queries on DataTables. So I am using Query Syntax for this and reached up to this point. var dept_list= from dept in DtMapGuestDepartment.AsEnumerable() where dept.Field<long>("PK_GUEST_ID")==long.Parse(63) select dept; This should give me the list of all departments that has guest id =63 Now I want to select all departments_name and parent_name from Table 2 where guest_id=63 i.e. departments that i fetched above. This same case will be followed for Table3. Please suggest how to do this. Thanks for keeping up patience for reading my question.

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• Any way to speed up this hierarchical query?

  - by RenderIn

  I've got a serious performance problem with a hierarchical query that I can't seem to fix. I am modeling several organization charts in my database, each representing a virtual organization within our company. For example, we have several temporary committees that are created from time to time and there may be a Committee Organizer role at the top of this virtual hierarchy, with several people assigned to the Committee Member role beneath the organizer. Some of our virtual organizations have many levels and several branches at each level. I have a single table in which I represent all the role assignments. i.e. a ROLE_ID column and a PARENT_ROLE_ID column which is a foreign key to the ROLE_ID column. For each assignment we also store as a column the location in the company where this person has the assignment. For example, the Committee Organizer would have a company-level/ CEO assignment, while the committee members would have department-level assignments such as ACCOUNTING, MARKETING, etc. So to model the organizer/member relationship for two individuals we would have: ROLE_ID = 4 PARENT_ROLE_ID = NULL EMPLOYEE_NUMBER = 213423 COMPANY_LOCATION = CEO ROLE_ID = 5 PARENT_ROLE_ID = 4 EMPLOYEE_NUMBER = 838221 COMPANY_LOCATION = ACCOUNTING Here's where things get tricky. I have an application that every person in the organization can log in to. When they log in they should be able to view all the virtual organizations in our company. e.g. the committee members should be able to see the committee organizer and vice-versa. However, only the committee organizer should be able to edit the committee members. The difficulty is in determining whether an individual (who can have multiple role assignments) has edit access for each other assignment. While this seems simple in the example, consider a virtual organization in which we have President at the top, 5 departments directly beneath him, 2 subdepartments below each department. We only want people in the Accounting department to be able to edit individuals in the subdepartments belonging to the Accounting department. They should not have edit access to anybody in the Marketing department or its subdepartments. To determine edit access when a user views a virtual organization in our company I run a query that executes two inline views: A) Hierarchically query for all assignments in this virtual organization and using SYS_CONNECT_BY_PATH to store the entire path to each user/role/company_location and B) Hierarchically retrieve all the assignments the individual logged in has and using the SYS_CONNECT_BY_PATH to store the entire path to each of these assignments. The result of the query is all the records from A) plus a boolean determined by joining with B) which flags whether the logged in user has edit access for each record. Indexes don't seem to be helping... it simply appears that there is too much processing going on to separate all the records and then determine edit access. One issue is that I can't store the SYS_CONNECT_BY_PATH and index it... determining whether an individual record has edit access consists of comparing if: test_record_sys_path LIKE individual_record_sys_path || '%' Is a materialized view the answer?

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• Entity Framework Update Entity along with child entities (add/update as necessary)

  - by Jorin

  I have a many-to-many relationship between Issues and Scopes in my EF Context. In ASP.NET MVC, I bring up an Edit form that allows the user to edit a particular Issue. At the bottom of the form, is a list of checkboxes that allow them to select which scopes apply to this issue. When editing an issue, it likely will always have some Scopes associated with it already--these boxes will be checked already. However, the user has the opportunity to check more scopes or remove some of the currently checked scopes. My code looked something like this to save just the Issue: using (var edmx = new MayflyEntities()) { Issue issue = new Issue { IssueID = id, TSColumn = formIssue.TSColumn }; edmx.Issues.Attach(issue); UpdateModel(issue); if (ModelState.IsValid) { //if (edmx.SaveChanges() != 1) throw new Exception("Unknown error. Please try again."); edmx.SaveChanges(); TempData["message"] = string.Format("Issue #{0} successfully modified.", id); } } So, when I try to add in the logic to save the associated scopes, I tried several things, but ultimately, this is what made the most sense to me: using (var edmx = new MayflyEntities()) { Issue issue = new Issue { IssueID = id, TSColumn = formIssue.TSColumn }; edmx.Issues.Attach(issue); UpdateModel(issue); foreach (int scopeID in formIssue.ScopeIDs) { var thisScope = new Scope { ID = scopeID }; edmx.Scopes.Attach(thisScope); thisScope.ProjectID = formIssue.ProjectID; if (issue.Scopes.Contains(thisScope)) { issue.Scopes.Attach(thisScope); //the scope already exists } else { issue.Scopes.Add(thisScope); // the scope needs to be added } } if (ModelState.IsValid) { //if (edmx.SaveChanges() != 1) throw new Exception("Unknown error. Please try again."); edmx.SaveChanges(); TempData["message"] = string.Format("Issue #{0} successfully modified.", id); } } But, unfortunately, that just throws the following exception: An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key. What am I doing wrong?

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• Performance Optimization for Matrix Rotation

  - by Summer_More_More_Tea

  Hello everyone: I'm now trapped by a performance optimization lab in the book "Computer System from a Programmer's Perspective" described as following: In a N*N matrix M, where N is multiple of 32, the rotate operation can be represented as: Transpose: interchange elements M(i,j) and M(j,i) Exchange rows: Row i is exchanged with row N-1-i A example for matrix rotation(N is 3 instead of 32 for simplicity): ------- ------- |1|2|3| |3|6|9| ------- ------- |4|5|6| after rotate is |2|5|8| ------- ------- |7|8|9| |1|4|7| ------- ------- A naive implementation is: #define RIDX(i,j,n) ((i)*(n)+(j)) void naive_rotate(int dim, pixel *src, pixel *dst) { int i, j; for (i = 0; i < dim; i++) for (j = 0; j < dim; j++) dst[RIDX(dim-1-j, i, dim)] = src[RIDX(i, j, dim)]; } I come up with an idea by inner-loop-unroll. The result is: Code Version Speed Up original 1x unrolled by 2 1.33x unrolled by 4 1.33x unrolled by 8 1.55x unrolled by 16 1.67x unrolled by 32 1.61x I also get a code snippet from pastebin.com that seems can solve this problem: void rotate(int dim, pixel *src, pixel *dst) { int stride = 32; int count = dim >> 5; src += dim - 1; int a1 = count; do { int a2 = dim; do { int a3 = stride; do { *dst++ = *src; src += dim; } while(--a3); src -= dim * stride + 1; dst += dim - stride; } while(--a2); src += dim * (stride + 1); dst -= dim * dim - stride; } while(--a1); } After carefully read the code, I think main idea of this solution is treat 32 rows as a data zone, and perform the rotating operation respectively. Speed up of this version is 1.85x, overwhelming all the loop-unroll version. Here are the questions: In the inner-loop-unroll version, why does increment slow down if the unrolling factor increase, especially change the unrolling factor from 8 to 16, which does not effect the same when switch from 4 to 8? Does the result have some relationship with depth of the CPU pipeline? If the answer is yes, could the degrade of increment reflect pipeline length? What is the probable reason for the optimization of data-zone version? It seems that there is no too much essential difference from the original naive version. EDIT: My test environment is Intel Centrino Duo processor and the verion of gcc is 4.4 Any advice will be highly appreciated! Kind regards!

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• Under what circumstances is an SqlConnection automatically enlisted in an ambient TransactionScope T

  - by Triynko

  What does it mean for an SqlConnection to be "enlisted" in a transaction? Does it simply mean that commands I execute on the connection will participate in the transaction? If so, under what circumstances is an SqlConnection automatically enlisted in an ambient TransactionScope Transaction? See questions in code comments. My guess to each question's answer follows each question in parenthesis. Scenario 1: Opening connections INSIDE a transaction scope using (TransactionScope scope = new TransactionScope()) using (SqlConnection conn = ConnectToDB()) { // Q1: Is connection automatically enlisted in transaction? (Yes?) // // Q2: If I open (and run commands on) a second connection now, // with an identical connection string, // what, if any, is the relationship of this second connection to the first? // // Q3: Will this second connection's automatic enlistment // in the current transaction scope cause the transaction to be // escalated to a distributed transaction? (Yes?) } Scenario 2: Using connections INSIDE a transaction scope that were opened OUTSIDE of it //Assume no ambient transaction active now SqlConnection new_or_existing_connection = ConnectToDB(); //or passed in as method parameter using (TransactionScope scope = new TransactionScope()) { // Connection was opened before transaction scope was created // Q4: If I start executing commands on the connection now, // will it automatically become enlisted in the current transaction scope? (No?) // // Q5: If not enlisted, will commands I execute on the connection now // participate in the ambient transaction? (No?) // // Q6: If commands on this connection are // not participating in the current transaction, will they be committed // even if rollback the current transaction scope? (Yes?) // // If my thoughts are correct, all of the above is disturbing, // because it would look like I'm executing commands // in a transaction scope, when in fact I'm not at all, // until I do the following... // // Now enlisting existing connection in current transaction conn.EnlistTransaction( Transaction.Current ); // // Q7: Does the above method explicitly enlist the pre-existing connection // in the current ambient transaction, so that commands I // execute on the connection now participate in the // ambient transaction? (Yes?) // // Q8: If the existing connection was already enlisted in a transaction // when I called the above method, what would happen? Might an error be thrown? (Probably?) // // Q9: If the existing connection was already enlisted in a transaction // and I did NOT call the above method to enlist it, would any commands // I execute on it participate in it's existing transaction rather than // the current transaction scope. (Yes?) }

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• Rails / ActiveRecord Modeling Help

  - by JM

  I’m trying to model a relationship in ActiveRecord and I think it’s a little beyond my skill level. Here’s the background. This is a horse racing project and I’m trying to model a horses Connections over time. Connections are defined as the Horse’s Current: Owner, Trainer and Jockey. Over time, a horse’s connections can change for a lot of different reasons: The owner sells the horse in a private sale The horse is claimed (purchase in a public sale) The Trainer switches jockeys The owner switches trainers In my first attempt at modeling this, I created the following tables: Horses, Owners, Trainers, Jockeys and Connections. Essentially, the Connections table was the has-many-through join table and was structured as follows: Connections Table 1 Id Horse_id Owner_id Trainer_id Jockey_id Status_Code Status_Date Change_Code The Horse, Owner, Trainer and Jockey foreign keys are self explanatory. The status code is 1 or 0 (1 active, 0 inactive) and the status date is the date the status changed. Change_code is and integer or string value that represent the reason for the change (private sale, claim, jockey change, etc) The key benefit of this approach is that the Connection is represented as one record in the connections table. The downside is that I have to have a table for Owner (1), Trainer (2) and Jockey (3) when one table could due. In my second attempt at modeling this I created the following tables: Horses, Connections, Entities The Entities tables has the following structure Entities Table id First_name Last_name Role where Role represents if the entity is a Owner, Trainer or Jockey. Under this approach, my Connections table has the following structure Connections Table 2 id Horse_id Entity_id Role Status_Code Status_Date Change_Code 1 1 1 1 1 1/1/2010 2 1 4 2 1 1/1/2010 3 1 10 3 1 1/1/2010 This approach has the benefit of eliminating two tables, but on the other hand the Connection is now comprised of three different records as opposed to one in the first approach. What believe I’m looking for is an approach that allows me to capture the Connection in one record, but also uses an Entities table with roles instead of the Owner, Trainer and Jockey tables. I’m new to ActiveRecord and rails so any and all input would be greatly appreciated. Perhaps there are other ways that would even be better. Thanks!

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• JSF: how to update the list after delete an item of that list

  - by Harry Pham

  It will take a moment for me to explain this, so please stay with me. I have table COMMENT that has OneToMany relationship with itself. @Entity public class Comment(){ ... @ManyToOne(optional=true, fetch=FetchType.LAZY) @JoinColumn(name="REPLYTO_ID") private Comment replyTo; @OneToMany(mappedBy="replyTo", cascade=CascadeType.ALL) private List<Comment> replies = new ArrayList<Comment>(); public void addReply(NewsFeed reply){ replies.add(reply); reply.setReplyTo(this); } public void removeReply(NewsFeed reply){ replies.remove(reply); } } So you can think like this. Each comment can have a List of replies which are also type Comment. Now it is very easy for me to delete the original comment and get the updated list back. All I need to do after delete is this. allComments = myEJB.getAllComments(); //This will query the db and return updated list But I am having problem when trying to delete replies and getting the updated list back. So here is how I delete the replies. Inside my managed bean I have //Before invoke this method, I have the value of originalFeed, and deletedFeed set. //These original comments are display inside a p:dataTable X, and the replies are //displayed inside p:dataTable Y which is inside X. So when I click the delete button //I know which comment I want to delete, and if it is the replies, I will know //which one is its original post public void deleteFeed(){ if(this.deletedFeed != null){ scholarEJB.deleteFeeds(this.deletedFeed); if(this.originalFeed != null){ //Since the originalFeed is not null, this is the `replies` //that I want to delete scholarEJB.removeReply(this.originalFeed, this.deletedFeed); } feeds = scholarEJB.findAllFeed(); } } Then inside my EJB scholarEJB, I have public void removeReply(NewsFeed comment, NewsFeed reply){ comment = em.merge(comment); comment.removeReply(reply); em.persist(comment); } public void deleteFeeds(NewsFeed e){ e = em.find(NewsFeed.class, e.getId()); em.remove(e); } When I get out, the entity (the reply) get correctly removed from the database, but inside the feeds List, reference of that reply still there. It only until I log out and log back in that the reply disappear. Please help

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• Custom activity designers in Workflow Foundation 3.5: How do they work?

  - by stakx

  Intent of this post: I realise that Workflow Foundation is not extremely popular on StackOverflow and that there will probably be not many answers, or none at all. This post is intended as a resource to people trying to customise workflow activities' appearance through custom designer classes. Goals: I am attempting to create a custom designer class for Workflow activities to achieve the following: Make activities look less technical. For example, I don't necessarily want to see the internal object name as the activity's "title" -- instead, I'd like to see something more descriptive. Display the values of certain properties beneath the title text. I would like to see some properties' values directly underneath the title so that I don't need to look somewhere else (namely, at the Properties window). Provide custom drop areas and draw custom internal arrows. As an example, I would like to be able to have custom drop areas in very specific places. What I found out so far: I created a custom designer class deriving from SequentialActivityDesigner as follows: [Designer(typeof(SomeDesigner))] public partial class SomeActivity: CompositeActivity { ... } class PlainDesigner : SequentialActivityDesigner { ... } Through overriding some properties and the OnPaint method, I found out about the following correspondences between the properties and how the activity will be displayed: Figure 1. Relationship between some properties of an SequentialActivityDesigner and the displayed activity. Possible solutions for goal #1 (make activities look less technical) and goal #2 (display values of properties beneath title text): The displayed title can be changed through the Title property. If more room is required to display additional information beneath the title, the TitleHeight property can be increased (ie., override the property and make it return base.TitleHeight + n, where n is some positive integer). Override the OnPaint method and draw additional text in the area reserved through TitleHeight. Open questions: What are the connectors, connections, and connection points used for? They seem to be necessary, but for what purpose? While the drop targets can be got through the GetDropTargets method, it seems that this is not necessarily where the designer will actually place dropped activities. When an activity is dragged across a workflow, the designer displays little green plus signs where activities can be dropped; how does it figure out the locations of these plus signs? How does the designer figure out where to draw connector lines and arrows?

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• Foreign Key Relationships and "belongs to many"

  - by jan

  I have the following model: S belongs to T T has many S A,B,C,D,E (etc) have 1 T each, so the T should belong to each of A,B,C,D,E (etc) At first I set up my foreign keys so that in A, fk_a_t would be the foreign key on A.t to T(id), in B it'd be fk_b_t, etc. Everything looks fine in my UML (using MySQLWorkBench), but generating the yii models results in it thinking that T has many A,B,C,D (etc) which to me is the reverse. It sounds to me like either I need to have A_T, B_T, C_T (etc) tables, but this would be a pain as there are a lot of tables that have this relationship. I've also googled that the better way to do this would be some sort of behavior, such that A,B,C,D (etc) can behave as a T, but I'm not clear on exactly how to do this (I will continue to google more on this) What do you think is the better solution? UML: Here's the DDL (auto generated). Just pretend that there is more than 3 tables referencing T. -- ----------------------------------------------------- -- Table `mydb`.`T` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`T` ( `id` INT NOT NULL AUTO_INCREMENT , PRIMARY KEY (`id`) ) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`S` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`S` ( `id` INT NOT NULL AUTO_INCREMENT , `thing` VARCHAR(45) NULL , `t` INT NOT NULL , PRIMARY KEY (`id`) , INDEX `fk_S_T` (`id` ASC) , CONSTRAINT `fk_S_T` FOREIGN KEY (`id` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`A` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`A` ( `id` INT NOT NULL AUTO_INCREMENT , `T` INT NOT NULL , `stuff` VARCHAR(45) NULL , `bar` VARCHAR(45) NULL , `foo` VARCHAR(45) NULL , PRIMARY KEY (`id`) , INDEX `fk_A_T` (`T` ASC) , CONSTRAINT `fk_A_T` FOREIGN KEY (`T` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`B` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`B` ( `id` INT NOT NULL AUTO_INCREMENT , `T` INT NOT NULL , `stuff2` VARCHAR(45) NULL , `foobar` VARCHAR(45) NULL , `other` VARCHAR(45) NULL , PRIMARY KEY (`id`) , INDEX `fk_A_T` (`T` ASC) , CONSTRAINT `fk_A_T` FOREIGN KEY (`T` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`C` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`C` ( `id` INT NOT NULL AUTO_INCREMENT , `T` INT NOT NULL , `stuff3` VARCHAR(45) NULL , `foobar2` VARCHAR(45) NULL , `other4` VARCHAR(45) NULL , PRIMARY KEY (`id`) , INDEX `fk_A_T` (`T` ASC) , CONSTRAINT `fk_A_T` FOREIGN KEY (`T` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB;

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• Hibernate can't load Custom SQL collection

  - by Geln Yang

  Hi, There is a table Item like, code,name 01,parent1 02,parent2 0101,child11 0102,child12 0201,child21 0202,child22 Create a java object and hbm xml to map the table.The Item.parent is a Item whose code is equal to the first two characters of its code : class Item{ String code; String name; Item parent; List<Item> children; .... setter/getter.... } <hibernate-mapping> <class name="Item" table="Item"> <id name="code" length="4" type="string"> <generator class="assigned" /> </id> <property name="name" column="name" length="50" not-null="true" /> <many-to-one name="parent" class="Item" not-found="ignore"> <formula> <![CDATA[ (select i.code,r.name from Item i where (case length(code) when 4 then i.code=SUBSTRING(code,1,2) else false end)) ]]> </formula> </many-to-one> <bag name="children"></bag> </class> </hibernate-mapping> I try to use formula to define the many-to-one relationship,but it doesn't work!Is there something wrong?Or is there other method? Thanks! ps,I use mysql database. add 2010/05/23 Pascal's answer is right,but the "false" value must be replaced with other expression,like "1=2".Because the "false" value would be considered to be a column of the table. select i.code from Item i where ( case length(code) when 4 then i.code=SUBSTRING(code,1,2) else 1=2 end) And I have another question about the children "bag" mapping.There isn't formula configuration option for "bag",but we can use "loader" to load a sql-query.I configure the "bag" as following.But it get a list whose size is 0.What's wrong with it? <class> ... ... <bag name="children"> <key /> <one-to-many class="Item"></one-to-many> <loader query-ref="getChildren"></loader> </bag> </class> <sql-query name="getChildren"> <load-collection alias="r" role="Item.children" /> <![CDATA[(select {r.*} from Item r join Item o where o.code=:code and ( case length(o.code) when 2 then (length(r.code)=4 and SUBSTRING(r.code,1,2)=o.code) else 1=2 end ))]]> </sql-query>

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• How do I change a child's parent in NHibernate when cascade is delete-all-orphan?

  - by Daniel T.

  I have two entities in a bi-directional one-to-many relationship: public class Storage { public IList<Box> Boxes { get; set; } } public class Box { public Storage CurrentStorage { get; set; } } And the mapping: <class name="Storage"> <bag name="Boxes" cascade="all-delete-orphan" inverse="true"> <key column="Storage_Id" /> <one-to-many class="Box" /> </bag> </class> <class name="Box"> <many-to-one name="CurrentStorage" column="Storage_Id" /> </class> A Storage can have many Boxes, but a Box can only belong to one Storage. I have them mapped so that the one-to-many has a cascade of all-delete-orphan. My problem arises when I try to change a Box's Storage. Assuming I already ran this code: var storage1 = new Storage(); var storage2 = new Storage(); storage1.Boxes.Add(new Box()); Session.Create(storage1); Session.Create(storage2); The following code will give me an exception: // get the first and only box in the DB var existingBox = Database.GetBox().First(); // remove the box from storage1 existingBox.CurrentStorage.Boxes.Remove(existingBox); // add the box to storage2 after it's been removed from storage1 var storage2 = Database.GetStorage().Second(); storage2.Boxes.Add(existingBox); Session.Flush(); // commit changes to DB I get the following exception: NHibernate.ObjectDeletedException : deleted object would be re-saved by cascade (remove deleted object from associations) This exception occurs because I have the cascade set to all-delete-orphan. The first Storage detected that I removed the Box from its collection and marks it for deletion. However, when I added it to the second Storage (in the same session), it attempts to save the box again and the ObjectDeletedException is thrown. My question is, how do I get the Box to change its parent Storage without encountering this exception? I know one possible solution is to change the cascade to just all, but then I lose the ability to have NHibernate automatically delete a Box by simply removing it from a Storage and not re-associating it with another one. Or is this the only way to do it and I have to manually call Session.Delete on the box in order to remove it?

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• Issues with LINQ (to Entity) [adding records]

  - by Mario

  I am using LINQ to Entity in a project, where I pull a bunch of data (from the database) and organize it into a bunch of objects and save those to the database. I have not had problems writing to the db before using LINQ to Entity, but I have run into a snag with this particular one. Here's the error I get (this is the "InnerException", the exception itself is useless!): New transaction is not allowed because there are other threads running in the session. I have seen that before, when I was trying to save my changes inside a loop. In this case, the loop finishes, and it tries to make that call, only to give me the exception. Here's the current code: try { //finalResult is a list of the keys to match on for the records being pulled foreach (int i in finalResult) { var queryEff = (from eff in dbMRI.MemberEligibility where eff.Member_Key == i && eff.EffDate >= DateTime.Now select eff.EffDate).Min(); if (queryEff != null) { //Add a record to the Process table Process prRecord = new Process(); prRecord.GroupData = qa; prRecord.Member_Key = i; prRecord.ProcessDate = DateTime.Now; prRecord.RecordType = "F"; prRecord.UsernameMarkedBy = "Autocard"; prRecord.GroupsId = qa.GroupsID; prRecord.Quantity = 2; prRecord.EffectiveDate = queryEff; dbMRI.AddObject("Process", prRecord); } } dbMRI.SaveChanges(); //<-- Crashes here foreach (int i in finalResult) { var queryProc = from pro in dbMRI.Process where pro.Member_Key == i && pro.UsernameMarkedBy == "Autocard" select pro; foreach (var qp in queryProc) { Audit aud = new Audit(); aud.Member_Key = i; aud.ProcessId = qp.ProcessId; aud.MarkDate = DateTime.Now; aud.MarkedByUsername = "Autocard"; aud.GroupData = qa; dbMRI.AddObject("Audit", aud); } } dbMRI.SaveChanges(); //<-- AND here (if the first one is commented out) } catch (Exception e) { //Do Something here } Basically, I need it to insert a record, get the identity for that inserted record and insert a record into another table with the identity from the first record. Given some other constraints, it is not possible to create a FK relationship between the two (I've tried, but some other parts of the app won't allow it, AND my DBA team for whatever reason hates FK's, but that's for a different topic :)) Any ideas what might be causing this? Thank!

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• Advanced SQL query with lots of joins

  - by lund.mikkel

  Hey fellow programmers Okay, first let me say that this is a hard one. I know the presentation may be a little long. But I how you'll bare with me and help me through anyway :D So I'm developing on an advanced search for bicycles. I've got a lot of tables I need to join to find all, let's say, red and brown bikes. One bike may come in more then one color! I've made this query for now: SELECT DISTINCT p.products_id, #simple product id products_name, #product name products_attributes_id, #color id pov.products_options_values_name #color name FROM products p LEFT JOIN products_description pd ON p.products_id = pd.products_id INNER JOIN products_attributes pa ON pa.products_id = p.products_id LEFT JOIN products_options_values pov ON pov.products_options_values_id = pa.options_values_id LEFT JOIN products_options_search pos ON pov.products_options_values_id = pos.products_options_values_id WHERE pos.products_options_search_id = 4 #code for red OR pos.products_options_search_id = 5 #code for brown My first concern is the many joins. The Products table mainly holds product id and it's image and the Products Description table holds more descriptive info such as name (and product ID of course). I then have the Products Options Values table which holds all the colors and their IDs. Products Options Search is containing the color IDs along with a color group ID (products_options_search_id). Red has the color group code 4 (brown is 5). The products and colors have a many-to-many relationship managed inside Products Attributes. So my question is first of all: Is it okay to make so many joins? Is i hurting the performance? Second: If a bike comes in both red and brown, it'll show up twice even though I use SELECT DISTINCT. Think this is because of the INNER JOIN. Is this possible to avoid and do I have to remove the doubles in my PHP code? Third: Bikes can be double colored (i.e. black and blue). This means that there are two rows for that bike. One where it says the color is black and one where is says its blue. (See second question). But if I replace the OR in the WHERE clause it removes both rows, because none of them fulfill the conditions - only the product. What is the workaround for that? I really hope you will and can help me. I'm a little desperate right now :D Regards Mikkel Lund

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• NSLinguisticTagger on the contents of an NSTextStorage- crashing bug

  - by Remy Porter

  I'm trying to use an NSLinguisticTagger to monitor the contents of an NSTextStorage and provide some contextual information based on what the user types. To that end, I have an OverlayManager object, which wires up this relationship: -(void) setView:(NSTextView*) view { _view = view; _layout = view.layoutManager; _storage = view.layoutManager.textStorage; //get the TextStorage from the view [_tagger setString:_storage.string]; //pull the string out, this grabs the mutable version [self registerForNotificationsOn:self->_storage]; //subscribe to the willProcessEditing notification } When an edit occurs, I make sure to trap it and notify the tagger (and yes, I know I'm being annoyingly inconsistent with member access, I'm rusty on Obj-C, I'll fix it later): - (void) textStorageWillProcessEditing:(NSNotification*) notification{ if ([self->_storage editedMask] & NSTextStorageEditedCharacters) { NSRange editedRange = [self->_storage editedRange]; NSUInteger delta = [self->_storage changeInLength]; [_tagger stringEditedInRange:editedRange changeInLength:delta]; //should notify the tagger of the changes [self highlightEdits:self]; } } The highlightEdits message delegates the job out to a pool of "Overlay" objects. Each contains a block of code similar to this: [tagger enumerateTagsInRange:range scheme:NSLinguisticTagSchemeLexicalClass options:0 usingBlock:^(NSString *tag, NSRange tokenRange, NSRange sentenceRange, BOOL *stop) { if (tag == PartOfSpeech) { [self applyHighlightToRange:tokenRange onStorage:storage]; } }]; And that's where the problem is- the enumerateTagsInRange method crashes out with a message: 2014-06-04 10:07:19.692 WritersEditor[40191:303] NSMutableRLEArray replaceObjectsInRange:withObject:length:: Out of bounds This problem doesn't occur if I don't link to the mutable copy of the underlying string and instead do a [[_storage string] copy], but obviously I don't want to copy the entire backing store every time I want to do tagging. This all should be happening in the main run loop, so I don't think this is a threading issue. The NSRange I'm enumerating tags on exists both in the NSTextStorage and in the NSLinguisticTagger's view of the string. It's not even the fact that the applyHighlightToRange call adds attributes to the string, because it crashes before even reaching that line. I attempted to build a test case around the problem, but can't replicate it in those situations: - (void) testEdit { NSAttributedString* str = [[NSMutableAttributedString alloc] initWithString:@"Quickly, this is a test."]; text = [[NSTextStorage alloc] initWithAttributedString:str]; NSArray* schemes = [NSLinguisticTagger availableTagSchemesForLanguage:@"en"]; tagger = [[NSLinguisticTagger alloc] initWithTagSchemes:schemes options:0]; [tagger setString:[text string]]; [text beginEditing]; [[text mutableString] appendString:@"T"]; NSRange edited = [text editedRange]; NSUInteger length = [text changeInLength]; [text endEditing]; [tagger stringEditedInRange:edited changeInLength:length]; [tagger enumerateTagsInRange:edited scheme:NSLinguisticTagSchemeLexicalClass options:0 usingBlock:^(NSString *tag, NSRange tokenRange, NSRange sentenceRange, BOOL *stop) { //doesn't matter, this should crash }]; } That code doesn't crash.

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• SQLAlchemy unsupported type error - and table design issues?

  - by Az

  Hi there, back again with some more SQLAlchemy shenanigans. Let me step through this. My table is now set up as so: engine = create_engine('sqlite:///:memory:', echo=False) metadata = MetaData() students_table = Table('studs', metadata, Column('sid', Integer, primary_key=True), Column('name', String), Column('preferences', Integer), Column('allocated_rank', Integer), Column('allocated_project', Integer) ) metadata.create_all(engine) mapper(Student, students_table) Fairly simple, and for the most part I've been enjoying the ability to query almost any bit of information I want provided I avoid the error cases below. The class it is mapped from is: class Student(object): def __init__(self, sid, name): self.sid = sid self.name = name self.preferences = collections.defaultdict(set) self.allocated_project = None self.allocated_rank = 0 def __repr__(self): return str(self) def __str__(self): return "%s %s" %(self.sid, self.name) Explanation: preferences is basically a set of all the projects the student would prefer to be assigned. When the allocation algorithm kicks in, a student's allocated_project emerges from this preference set. Now if I try to do this: for student in students.itervalues(): session.add(student) session.commit() It throws two errors, one for the allocated_project column (seen below) and a similar error for the preferences column: sqlalchemy.exc.InterfaceError: (InterfaceError) Error binding parameter 4 - probably unsupported type. u'INSERT INTO studs (sid, name, allocated_rank, allocated_project) VALUES (?, ?, ?, ?, ?, ?, ?)' [1101, 'Muffett,M.', 1, 888 Human-spider relationships (Supervisor id: 123)] If I go back into my code I find that, when I'm copying the preferences from the given text files, it actually refers to the Project class which is mapped to a dictionary, using the unique project id's (pid) as keys. Thus, as I iterate through each student via their rank and to the preferences set, it adds not a project id, but the reference to the project id from the projects dictionary. students[sid].preferences[int(rank)].add(projects[int(pid)]) Now this is very useful to me since I can find out all I want to about a student's preferred projects without having to run another check to pull up information about the project id. The form you see in the error has the object print information passed as: return "%s %s (Supervisor id: %s)" %(self.proj_id, self.proj_name, self.proj_sup) My questions are: I'm trying to store an object in a database field aren't I? Would the correct way then, be copying the project information (project id, name, etc) into its own table, referenced by the unique project id? That way I can just have the project id field for one of the student tables just be an integer id and when I need more information, just join the tables? So and so forth for other tables? If the above makes sense, then how does one maintain the relationship with a column of information in one table which is a key index on another table? Does this boil down into a database design problem? Are there any other elegant ways of accomplishing this? Apologies if this is a very long-winded question. It's rather crucial for me to solve this, so I've tried to explain as much as I can, whilst attempting to show that I'm trying (key word here sadly) to understand what could be going wrong.

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