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  • Database Modelling - Conceptually different entities but with near identical fields

    - by Andrew Shepherd
    Suppose you have two sets of conceptual entities: MarketPriceDataSet which has multiple ForwardPriceEntries PoolPriceForecastDataSet which has multiple PoolPriceForecastEntry Both different child objects have near identical fields: ForwardPriceEntry has MarketPriceDataSetId (foreign key to parent table) StartDate EndDate SimulationItemId ForwardPrice PoolPriceForecastEntry has PoolPriceForecastDataSetId (foreign key to parent table) StartDate EndDate SimulationItemId ForecastPoolPrice If I modelled them as separate tables, the only difference would be the foreign key, and the name of the price field. There has been a debate as to whether the two near identical tables should be merged into one. Options I've thought of to model this is: Just keep them as two independent, separate tables Have both sets in the one table with an additional "type" field, and a parent_id equalling a foreign key to either parent table. This would sacrifice referential integrity checks. Have both sets in the one table with an additional "type" field, and create a complicated sequence of joining tables to maintain referential integrity. What do you think I should do, and why?

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  • C#: Get a list of every value for a given key in a set of dictionaries?

    - by Rosarch
    How can I write this code more cleanly/concisely? /// <summary> /// Creates a set of valid URIs. /// </summary> /// <param name="levelVariantURIDicts">A collection of dictionaries of the form: /// dict["filePath"] == theFilePath </param> /// <returns></returns> private ICollection<string> URIsOfDicts(ICollection<IDictionary<string, string>> levelVariantURIDicts) { ICollection<string> result = new HashSet<string>(); foreach (IDictionary<string, string> dict in levelVariantURIDicts) { result.Add(dict["filePath"]); } return result; }

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  • Is this more suited for key value storage or a tree?

    - by JC
    I'm trying to figure out the best way to represent some data. It basically follows the form Manufacturer.Product.Attribute = Value. Something like: Acme.*.MinimumPrice = 100 Acme.ProductA.MinimumPrice = 50 Acme.ProductB.MinimumPrice = 60 Acme.ProductC.DefaultColor = Blue So the minimum price across all Acme products is 100 except in the case of product A and B. I want to store this data in C# and have some function where GetValue("Acme.ProductC.MinimumPrice") returns 100 but GetValue("Acme.ProductA.MinimumPrice") return 50. I'm not sure how to best represent the data. Is there a clean way to code this in C#?

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  • Why does sorted list have to have a key value pair?

    - by clawson
    If I just want a sorted list of just dates, integers, or doubles is it really necessary to have to define a SortedList(of Integer, Integer)? Seems intriguing to me, but may just be trival. I'd prefer just to use a SortedList(of Integer). (This question is in relation to the .Net generic collections)

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  • Android ListView clears when hard BACK key is pressed.

    - by Rpond
    In my android app I have a Tabhost with a ListView as one of the tabs. By clicking on an item in the ListView (an address) I start an Intent to Google Maps for directions and the choice dialog pops up for google maps, web browser etc. Problem is if I press the hard back button then the launch dialog goes away but also the ListView is cleared. Any idea why?

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  • ISBNs are used as primary key, now I want to add non-book things to the DB - should I migrate to EAN

    - by fish2000
    I built an inventory database where ISBN numbers are the primary keys for the items. This worked great for a while as the items were books. Now I want to add non-books. some of the non-books have EANs or ISSNs, some do not. It's in PostgreSQL with django apps for the frontend and JSON api, plus a few supporting python command-line tools for management. the items in question are mostly books and artist prints, some of which are self-published. What is nice about using ISBNs as primary keys is that in on top of relational integrity, you get lots of handy utilities for validating ISBNs, automatically looking up missing or additional information on the book items, etcetera, many of which I've taken advantage. some such tools are off-the-shelf (PyISBN, PyAWS etc) and some are hand-rolled -- I tried to keep all of these parts nice and decoupled, but you know how things can get. I couldn't find anything online about 'private ISBNs' or 'self-assigned ISBNs' but that's the sort of thing I was interested in doing. I doubt that's what I'll settle on, since there is already an apparent run on ISBN numbers. should I retool everything for EAN numbers, or migrate off ISBNs as primary keys in general? if anyone has any experience with working with these systems, I'd love to hear about it, your advice is most welcome.

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  • Nhibernate multilevel hierarchy save error?

    - by nisbus
    Hi, I have a database with a 6 level hierarchy and a domain model on top of that. something like this: Category -SubCategory -Container -DataDescription | Meta data -Data The mapping I'm using follows the following pattern: <class name="Category, Sample" table="Categories"> <id name="Id" column="Id" type="System.Int32" unsaved-value="0"> <generator class="native"/> </id> <property name="Name" access="property" type="String" column="Name"/> <property name="Metadata" access="property" type="String" column="Metadata"/> <bag name="SubCategories" cascade="save-update" lazy="true" inverse="true"> <key column="Id" foreign-key="category_subCategory_fk"/> <one-to-many class="SubCategory, Sample" /> </bag> </class> <class name="SubCategory, Sample" table="SubCategories"> <id name="Id" column="Id" type="System.Int32" unsaved-value="0"> <generator class="native"/> </id> <many-to-one name="Category" class="Category, Sample" foreign-key="subCat_category_fk"/> <property name="Name" access="property" type="String"/> <property name="Metadata" access="property" type="String"/> <bag name="Containers" inverse="true" cascade="save-update" lazy="true"> <key column="Id" foreign-key="subCat_container_fk" /> <one-to-many class="Container, Sample" /> </bag> </class> <class name="Container, Sample" table="Containers"> <id name="Id" column="Id" type="System.Int32" unsaved-value="0"> <generator class="assigned"/> </id> <many-to-one name="SubCategory" class="SubCategory,Sample" foreign-key="container_subCat_fk"/> <property name="Name" access="property" type="String" column="Name"/> <bag name="DataDescription" cascade="all" lazy="true" inverse="true"> <key column="Id" foreign-key="container_ DataDescription_fk"/> <one-to-many class="DataDescription, Sample" /> </bag> <bag name="MetaData" cascade="all" lazy="true" inverse="true"> <key column="Id" foreign-key="container_metadata_cat_fk"/> <one-to-many class="MetaData, Sample" /> </bag> </class> For some reason when I try to save the category (with the subcategory, container etc. attached) I get a foreign key violation from the database. The code is something like this (Pseudo). var category = new Category(); var subCategory = new SubCategory(); var container = new Container(); var dataDescription = new DataDescription(); var metaData = new MetaData(); category.AddSubCategory(subCategory); subCategory.AddContainer(container); container.AddDataDescription(dataDescription); container.AddMetaData(metaData); Session.Save(category); Here is the log from this test : DEBUG NHibernate.SQL - INSERT INTO Categories (Name, Metadata) VALUES (@p0, @p1); select SCOPE_IDENTITY(); @p0 = 'Unit test', @p1 = 'unit test' DEBUG NHibernate.SQL - INSERT INTO SubCategories (Category, Name, Metadata) VALUES (@p0, @p1, @p2); select SCOPE_IDENTITY(); @p0 = '1', @p1 = 'Unit test', @p2 = 'unit test' DEBUG NHibernate.SQL - INSERT INTO Containers (SubCategory, Name, Frequency, Scale, Measurement, Currency, Metadata, Id) VALUES (@p0, @p1, @p2, @p3, @p4, @p5, @p6, @p7); @p0 = '1', @p1 = 'Unit test', @p2 = '15', @p3 = '1', @p4 = '1', @p5 = '1', @p6 = 'unit test', @p7 = '0' ERROR NHibernate.Util.ADOExceptionReporter - The INSERT statement conflicted with the FOREIGN KEY constraint "subCat_container_fk". The conflict occurred in database "Sample", table "dbo.SubCategories", column 'Id'. The methods for adding items to objects is always as follows: public void AddSubCategory(ISubCategory subCategory) { subCategory.Category = this; SubCategories.Add(subCategory); } What am I missing?? Thanks, nisbus

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  • Is there a supplementary guide/answer key for ruby koans?

    - by corroded
    I have recently tried sharpening my rails skills with this tool: http://github.com/edgecase/ruby_koans but I am having trouble passing some tests. Also I am not sure if I'm doing some things correctly since the objective is just to pass the test, there are a lot of ways in passing it and I may be doing something that isn't up to standards. Is there a way to confirm if I'm doing things right? a specific example: in about_nil, def test_nil_is_an_object assert_equal __, nil.is_a?(Object), "Unlike NULL in other languages" end so is it telling me to check if that second clause is equal to an object(so i can say nil is an object) or just put assert_equal true, nil.is_a?(Object) because the statement is true? and the next test: def test_you_dont_get_null_pointer_errors_when_calling_methods_on_nil # What happens when you call a method that doesn't exist. The # following begin/rescue/end code block captures the exception and # make some assertions about it. begin nil.some_method_nil_doesnt_know_about rescue Exception => ex # What exception has been caught? assert_equal __, ex.class # What message was attached to the exception? # (HINT: replace __ with part of the error message.) assert_match(/__/, ex.message) end end Im guessing I should put a "No method error" string in the assert_match, but what about the assert_equal?

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  • Arch Linux: How to handle patches which only you will use?

    - by user12932
    I'm using freerdp together with xmonad and it has been giving me a lot of trouble. The super key (or "windows key") is my mod key in xmonad and it has been interfering with my freerdp usage rather annoyingly. Whenever I switched workspaces (or did anything else in xmonad involving the super key), windows (controlled by the freerdp instance in focus) registered a keypress as well. This event combined with the loss of focus got the super key stuck in windows indefinitely: the press of the keys d and r would first show my desktop, then open the run dialog (as if I was pressing the windows key constantly). I've tried several versions of freerdp, but all exhibited this annoying behavior. So I resorted to patching freerdp myself to just ignore the left super key on my keyboard. I love free software for a lot of reasons (especially the ability to alter things like this myself), however I still find it annoying to patch and rebuild freerdp on all version (and dependency) changes. How do you deal with situations like this? Is there even a "right way" to resolve this issue?

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  • Is there a way to transfrom a list of key/value pairs into a data transfer object

    - by weevie
    ...apart from the obvious looping through the list and a dirty great case statement! I've turned over a few Linq queries in my head but nothing seems to get anywhere close. Here's the an example DTO if it helps: class ClientCompany { public string Title { get; private set; } public string Forenames { get; private set; } public string Surname { get; private set; } public string EmailAddress { get; private set; } public string TelephoneNumber { get; private set; } public string AlternativeTelephoneNumber { get; private set; } public string Address1 { get; private set; } public string Address2 { get; private set; } public string TownOrDistrict { get; private set; } public string CountyOrState { get; private set; } public string PostCode { get; private set; } } We have no control over the fact that we're getting the data in as KV pairs, I'm afraid.

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  • Database Modelling - Conceptually different entities with near identical fields

    - by Andrew Shepherd
    Suppose you have two sets of conceptual entities: MarketPriceDataSet which has multiple ForwardPriceEntries PoolPriceForecastDataSet which has multiple PoolPriceForecastEntry Both different child objects have near identical fields: ForwardPriceEntry has StartDate EndDate SimulationItemId ForwardPrice MarketPriceDataSetId (foreign key to parent table) PoolPriceForecastEntry has StartDate EndDate SimulationItemId ForecastPoolPrice PoolPriceForecastDataSetId (foreign key to parent table) If I modelled them as separate tables, the only difference would be the foreign key, and the name of the price field. There has been a debate as to whether the two near identical tables should be merged into one. Options I've thought of to model this is: Just keep them as two independent, separate tables Have both sets in the one table with an additional "type" field, and a parent_id equalling a foreign key to either parent table. This would sacrifice referential integrity checks. Have both sets in the one table with an additional "type" field, and create a complicated sequence of joining tables to maintain referential integrity. What do you think I should do, and why?

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  • Having some fun - what is a good way to include a secret key functionality and fire the KeyDown event?

    - by Sisyphus
    To keep myself interested, I try to put little Easter Eggs in my projects (mostly to amuse myself). I've seen some websites where you can type a series of letters "aswzaswz" and you get a "secret function" - how would I achieve this in C#? I've assigned a "secret function" in the past by using modifier keys bool showFunThing = (Control.ModifierKeys & Keys.Control) == Keys.Control; but wanted to get a bit more secretive (without the modifier keys) I just wanted the form to detect a certain word typed without any input ... I've built a method that I think should do it: private StringBuilder _pressedKeys = new StringBuilder(); protected override void OnKeyDown(KeyEventArgs e) { const string kWord = "fun"; char letter = (char)e.KeyValue; if (!char.IsLetterOrDigit(letter)) { return; } _pressedKeys.Append(letter); if (_pressedKeys.Length == kWord.Length) { if (_pressedKeys.ToString().ToLower() == kWord) { MessageBox.Show("Fun"); _pressedKeys.Clear(); } } base.OnKeyDown(e); } Now I need to wire it up but I can't figure out how I'm supposed to raise the event in the form designer ... I've tried this: this.KeyDown +=new System.Windows.Forms.KeyEventHandler(OnKeyDown); and a couple of variations on this but I'm missing something because it won't fire (or compile). It tells me that the OnKeyDown method is expecting a certain signature but I've got other methods like this where I haven't specified arguments. I fear that I may have got myself confused so I am turning to SO for help ... anyone?

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  • PHP elseif statement not executed even though initial if statement is false

    - by DarwinIcesurfer
    I am writing a recursive function to print out the differences between 2 multildimensional php arrays. The purpose of this code is to see the difference between jpeg headers to deteremine how adobe bridge cs3 is saving rating information within the jpg file. When I am single-stepping through the code using my eclipse - zend debugger ide, it appears that even though the initial if statement is false (ie both values are arrays), the subsequent elseif statements are never executed. The function is attached below. function array_diff_multi($array1,$array2,$level){ $keys = array_keys($array1); foreach($keys as $key) { $value1 = $array1[$key]; if(array_key_exists($key,$array2) ){ $value2 = $array2[$key]; // Check if they are both arrays, if so recursion is needed if (is_array($value1) && is_array($value2)){ array_diff_multi($value1,$value2,$level . "[ " . $key . " ]"); } // the values aren't both arrays *** THE CODE IN THE ELSEIF BELOW IS NOT EXECUTED *** elseif(is_array($value1) != is_array($value2)){ print "" . $level . $key ."=" . $value1 . "as array, compared to ". $value2 .""; } // the values don't match elseif($value1 != $value2){ print "" . $level . $key ."=" . $value1 ." != " . $value2 .""; } else; } else{ print "" . $level. $key . "does not exist in array2"; } } }

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  • How can I change what happens when "enter" key is pressed on a DataGridView?

    - by SO give me back my rep
    when I am editing a cell and press enter the next row is automatically selected, I want to stay with the current row... I want to happen nothing except the EndEdit. I have this: private void dtgProductos_CellEndEdit(object sender, DataGridViewCellEventArgs e) { dtgProductos[e.ColumnIndex, e.RowIndex].Selected = true; //this line is not working var index = dtgProductos.SelectedRows[0].Cells.IndexOf(dtgProductos.SelectedRows[0].Cells[e.ColumnIndex]); switch (index) { case 2: { dtgProductos.SelectedRows[0].Cells[4].Selected = true; dtgProductos.BeginEdit(true); } break; case 4: { dtgProductos.SelectedRows[0].Cells[5].Selected = true; dtgProductos.BeginEdit(true); } break; case 5: { btnAddProduct.Focus(); } break; default: break; } } so when I edit a row that is not the last one I get this error: Operation is not valid because it results in a reentrant call to the SetCurrentCellAddressCore function.

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  • Type classe, generic memoization

    - by nicolas
    Something quite odd is happening with y types and I quite dont understand if this is justified or not. I would tend to think not. This code works fine : type DictionarySingleton private () = static let mutable instance = Dictionary<string*obj, obj>() static member Instance = instance let memoize (f:'a -> 'b) = fun (x:'a) -> let key = f.ToString(), (x :> obj) if (DictionarySingleton.Instance).ContainsKey(key) then let r = (DictionarySingleton.Instance).[key] r :?> 'b else let res = f x (DictionarySingleton.Instance).[key] <- (res :> obj) res And this ones complains type DictionarySingleton private () = static let mutable instance = Dictionary<string*obj, _>() static member Instance = instance let memoize (f:'a -> 'b) = fun (x:'a) -> let key = f.ToString(), (x :> obj) if (DictionarySingleton.Instance).ContainsKey(key) then let r = (DictionarySingleton.Instance).[key] r :?> 'b else let res = f x (DictionarySingleton.Instance).[key] <- (res :> obj) res The difference is only the underscore in the dictionary definition. The infered types are the same, but the dynamic cast from r to type 'b exhibits an error. 'this runtime coercition ... runtime type tests are not allowed on some types, etc..' Am I missing something or is it a rough edge ?

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  • How to compare dictonary key with xml attribute value in xml using LINQ in c #?

    - by Pramodh
    Dear all, i've a dictonary " dictSample " which contains 1 data1 2 data2 3 data3 4 data4 and an xml file"sample.xml" in the form of: <node> <element id="1" value="val1"/> <element id="2" value="val2"/> <element id="3" value="val3"/> <element id="4" value="val4"/> <element id="5" value="val5"/> <element id="6" value="val6"/> <element id="7" value="val7"/> </node> i need to match the dictonary keys with the xml attribute id and to insert the matching id and the value of attribute"value" into another dictonary now i'm using like: XmlDocument XDOC = new XmlDocument(); XDOC.Load("Sample.xml"); XmlNodeList NodeList = XDOC.SelectNodes("//element"); Dictionary<string, string> dictTwo = new Dictionary<string, string>(); foreach (string l_strIndex in dictSample .Keys) { foreach (XmlNode XNode in NodeList) { XmlElement XEle = (XmlElement)XNode; if (dictSample[l_strIndex] == XEle.GetAttribute("id")) dictTwo.Add(dictSample[l_strIndex], XEle.GetAttribute("value").ToString()); } } please help me to do this in a simple way using LINQ

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  • How can I get an e-mail address out of a string of key=value pairs?

    - by noob
    How can I get some part of string that I need? accountid=xxxxxx type=prem servertime=1256876305 addtime=1185548735 validuntil=1265012019 username=noob directstart=1 protectfiles=0 rsantihack=1 plustrafficmode=1 mirrors= jsconfig=1 [email protected] lots=0 fpoints=6076 ppoints=149 curfiles=38 curspace=3100655714 bodkb=60000000 premkbleft=25000000 ppointrate=116 I want data after email= but up to live.com.?

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  • Fluent nHibernate - How to map a non-key column on an association table?

    - by The Matt
    Taking an example that is provided on the Fluent nHibernate website, I need to extend it slightly: I need to add a 'Quantity' column to the StoreProduct table. How would I map this using nHibernate? An example mapping is provided for the given scenario above, but I'm not sure how I would get the Quantity column to map: public class StoreMap : ClassMap<Store> { public StoreMap() { Id(x => x.Id); Map(x => x.Name); HasMany(x => x.Employee) .Inverse() .Cascade.All(); HasManyToMany(x => x.Products) .Cascade.All() .Table("StoreProduct"); } }

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  • Spring's JdbcDaoSupport (using MySQL Connector/J) fails after executing sql that adds FK

    - by John
    I am using Spring's JdbcDaoSupport class with a DriverManagerDataSource using the MySQL Connector/J 5.0 driver (driverClassName=com.mysql.jdbc.driver). allowMultiQueries is set to true in the url. My application is an in-house tool we recently developed that executes sql scripts in a directory one-by-one (allows us to re-create our schema and reference table data for a given date, etc, but I digress). The sql scripts sometime contain multiple statements (hence allowMultiQueries), so one script can create a table, add indexes for that table, etc. The problem happens when including a statement to add a foreign key constraint in one of these files. If I have a file that looks like... --(column/constraint names are examples) CREATE TABLE myTable ( fk1 BIGINT(19) NOT NULL, fk2 BIGINT(19) NOT NULL, PRIMARY KEY (fk1, fk2) ); ALTER TABLE myTable ADD CONSTRAINT myTable_fk1 FOREIGN KEY (fk1) REFERENCES myOtherTable (id) ; ALTER TABLE myTable ADD CONSTRAINT myTable_fk2 FOREIGN KEY (fk2) REFERENCES myOtherOtherTable (id) ; then JdbcTemplate.execute throws an UncategorizedSqlException with the following error message and stack trace: Exception in thread "main" org.springframework.jdbc.UncategorizedSQLException: StatementCallback; uncategorized SQLException for SQL [ THE SQL YOU SEE ABOVE LISTED HERE ]; SQL state [HY000]; error code [1005]; Can't create table 'myDatabase.myTable' (errno: 150); nested exception is java.sql.SQLException: Can't create table 'myDatabase.myTable' (errno: 150) at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:83) at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:80) at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:80) and the table and foreign keys are not inserted. Also, especially weird: if I take the foreign key statements out of the script I showed above and then place them in their own script that executes after (so I now have 1 script with just the create table statement, and 1 script with the add foreign key statements that executes after that) then what happens is: tool executes create table script, works fine, table is created tool executes add fk script, throws the same exception as seen above (except errno=121 this time), but the FKs actually get added (!!!) In other words, when the create table/FK statements are in the same script then the exception is thrown and nothing is created, but when they are different scripts a nearly identical exception is thrown but both things get created. Any help on this would be greatly appreciated. Please let me know if you'd like me to clarify anything more.

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