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  • NSPredicate as a constraint solver?

    - by Felixyz
    I'm working on a project which includes some slightly more complex dynamic layout of interface elements than what I'm used to. I always feel stupid writing complex code that checks if so-and-so is close to such-and-such and in that case move it x% in some direction, etc. That's just not how programming should be done. Programming should be as declarative as possible! Precisely because what I'm going to do is fairly simple, I thought it would be a good opportunity to try something new, and I thought of using NSPredicate as a simple constraints solver. I've only used NSPredicate for very simple tasks so far, but I know that it capable of much more. Are there any ideas, experiences, examples, warnings, insights that could be useful here? I'll give a very simple example so there will be something concrete to answer. How could I use NSPredicate to solve the following constraints: viewB.xmid = (viewB.leftEdge + viewB.width) / 2 viewB.xmid = max(300, viewA.rightEdge + 20 + viewB.width/2) ("viewB should be horizontally centered on coordinate 300, unless its left edge gets within 20 pixels of viewB's right edge, in which case viewA's left edge should stay fixed at 20 pixels to the right of viewB's right edge and viewA's horizontal center get pushed to the right.") viewA.rightEdge and viewB.width can vary, and those are the 'input variables'. EDIT: Any solution would probably have to use the NSExpression method -(id)expressionValueWithObject:(id)object context:(NSMutableDictionary *)context. This answer is relevant.

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  • EF problem with entity re-ordering and uniqueness constraint

    - by wpfwannabe
    I am using Entity Framework and I've come to an interesting stumbling block. Let's say there is a db table "Item" with "sequence" column of type int (and others of course). Column "sequence" must be unique and it is used for (re)ordering of items. EF maps this table to "Item" class with "sequence" int property. Now let's say I want to swap position of two items by mutually exchanging each other's sequence number. Upon calling SaveChanges() EF throws an exception complaining about "sequence" uniqueness. It probably generates two UPDATEs and the first one probably fails. I assume that plain SQL solution to this issue is using a third UPDATE to introduce a unique sequence value in the process but I am stuck with EF. Any thoughts?

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  • Violation of PRIMARY KEY constraint 'PK_

    - by abhi
    hi am trying to write a code in which i need to perform a update but on primary keys how do i achieve it i have written the following code: kindly look at it let me know where m wrong Protected Sub rgKMSLoc_UpdateCommand(ByVal source As Object, ByVal e As Telerik.Web.UI.GridCommandEventArgs) Handles rgKMSLoc.UpdateCommand Try KAYAReqConn.Open() If TypeOf e.Item Is GridEditableItem Then Dim strItemID As String = CType(e.Item.FindControl("hdnID"), HiddenField).Value Dim strrcmbLocation As String = CType(e.Item.FindControl("rcmbLocation"), RadComboBox).SelectedValue Dim strKubeLocation As String = CType(e.Item.FindControl("txtKubeLocation"), TextBox).Text Dim strCSVCode As String = CType(e.Item.FindControl("txtCSVCode"), TextBox).Text SQLCmd = New SqlCommand("SELECT * FROM MstKMSLocKubeLocMapping WHERE LocationID= '" & rcmbLocation.SelectedValue & "'", KAYAReqConn) Dim dr As SqlDataReader dr = SQLCmd.ExecuteReader If dr.HasRows Then lblMsgWarning.Text = "<font color=red>""User ID Already Exists" Exit Sub End If dr.Close() SQLCmd = New SqlCommand("UPDATE MstKMSLocKubeLocMapping SET LocationID=@Location,KubeLocation=@KubeLocation,CSVCode=@CSVCode WHERE LocationID = '" & strItemID & "'", KAYAReqConn) SQLCmd.Parameters.AddWithValue("@Location", Replace(strrcmbLocation, "'", "''")) SQLCmd.Parameters.AddWithValue("@KubeLocation", Replace(strKubeLocation, "'", "''")) SQLCmd.Parameters.AddWithValue("@CSVCode", Replace(strCSVCode, "'", "''")) SQLCmd.Parameters.AddWithValue("@Status", "A") SQLCmd.ExecuteNonQuery() lblMessageUpdate.Text = "<font color=blue>""Record Updated SuccessFully" SQLCmd.Dispose() rgKMSLoc.Rebind() End If Catch ex As Exception Response.Write(ex.ToString) Finally KAYAReqConn.Close() End Try End Sub this is my designer page' Location: ' / ' DataSourceID="dsrcmbLocation" DataTextField="Location" DataValueField="LocationID" Height="150px" Kube Location: ' Class="forTextBox" MaxLength="4" onkeypress="return filterInput(2,event);" CSV Code: ' Class="forTextBox" MaxLength="4" onkeypress="return filterInput(2,event);" <tr class="tableRow"> <td colspan="2" align="center" class="tableCell"> <asp:ImageButton ID="btnUpdate" runat="server" CommandName="Update" CausesValidation="true" ValidationGroup="Update" ImageUrl="~/Images/update.gif"></asp:ImageButton> <asp:ImageButton ID="btnCancel" runat="server" CausesValidation="false" CommandName="Cancel" ImageUrl="~/Images/No.gif"></asp:ImageButton> </td> </tr> </table> </FormTemplate> </EditFormSettings> Locationid is my primary key

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  • MySQL ignores the NOT NULL constraint

    - by Marga Keuvelaar
    I have created a table with NOT NULL constraints on some columns in MySQL. Then in PHP I wrote a script to insert data, with an insert query. When I omit one of the NOT NULL columns in this insert statement I would expect an error message from MySQL, and I would expect my script to fail. Instead, MySQL inserts empty strings in the NOT NULL fields. In other omitted fields the data is NULL, which is fine. Could someone tell me what I did wrong here? I'm using this table: CREATE TABLE IF NOT EXISTS tblCustomers ( cust_id int(11) NOT NULL AUTO_INCREMENT, custname varchar(50) NOT NULL, company varchar(50), phone varchar(50), email varchar(50) NOT NULL, country varchar(50) NOT NULL, ... date_added timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, PRIMARY KEY (cust_id) ) ; And this insert statement: $sql = "INSERT INTO tblCustomers (custname,company) VALUES ('".$customerName."','".$_POST["CustomerCompany"]."')"; $res = mysqli_query($mysqli, $sql);

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  • declaring constraint to consider prog logic

    - by shantanuo
    I can open a trip only once but can close it multiple times. I can not declare the Trip_no + status as primary key since there can be multiple entries while closing the trip. Is there any way that will assure me that a trip number is opened only once? For e.g. there should not be the second row with "Open" status for trip No. 3 since it is already there in the following table. Trip No | Status 1 Open 1 Close 1 Close 2 Open 2 Close 3 Open 3 Close 3 Close 3 Close 3 Close

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  • i need a query to retrieve the following constraint

    - by ANITHA
    I have the following tables and fields: +------------------+ +-------------------+ +---------------+ | Request | | RequestItem | | Item | +------------------+ +-------------------+ +---------------+ | + Requester_Name | | + Request_No | | + Item | +------------------+ +-------------------+ +---------------+ | + Request_No | | + Item | +------------------+ +-------------------+ I would like to filter the items which are selected under a particular request number, along with a specific requester name. How might I go about doing this?

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  • Enforcing a Uniqueness Constraint in a Nested Form

    - by Euwyn
    I'm trying not to fight the defaults here and use Rails built-in support for nested attributes (from http://ryandaigle.com/articles/2009/2/1/what-s-new-in-edge-rails-nested-attributes). I'm labeling Things with Tags, and all works swell, and for each Thing I have a form with a nested field that creates a new Tag by a name. Trouble is, I need to make sure that each Tag has a unique name. Instead of creating a new Tag, if a user enters the name of one that already exists, I need to create the associate with that pre-existing Tag. How do I do this?

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  • Best practices for handling unique constraint violation

    - by umesh awasthi
    Hi All, While working in my application i came across a situation in which there are likely chances to Unque Constraints Violation.I have following options Catch the exception and throw it back to UI At UI check for the exception and show approrpriate Error Message This is something different idea is to Check in advance about the existance of the given Unique value before starting the whole operation. My Question is what might be the best practice to handle such situation.Currently we are using combo of Struts2+Spring 3.x+Hibernate 3.x Thanks in advance

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  • Problem in inferring instances that have integer cardinality constraint

    - by Mikae Combarado
    Hello, I have created an RDF/OWL file using Protege 4.1 alpha. I also created a defined class in Protege called CheapPhone. This class has a restriction which is shown below : (hasPrice some integer[< 350]) Whenever, a price of a phone is below 350, it is inferred as CheapPhone. There is no problem for inferring this in Protege 4.1 alpha. However, I cannot infer this using Jena. I also created a defined class called SmartPhone. This class also has a restriction which is shown below : (has3G value true) and (hasInternet value true) Whenever, a phone has 3G and Internet, it is inferred as SmartPhone. In this situation, there is no problem inferring this in both Protege and Jena. I have started to think that there is a problem in default inference engine of Jena. The code that I use in Java is below : Reasoner reasoner = ReasonerRegistry.getOWLReasoner(); reasoner = reasoner.bindSchema(ontModel); OntModelSpec ontModelSpec = OntModelSpec.OWL_MEM_MINI_RULE_INF; ontModelSpec.setReasoner(reasoner); // Create ontology model with reasoner support // ontModel was created and read before, so I don't share the code in order // not to create garbage here OntModel model = ModelFactory.createOntologyModel(ontModelSpec, ontModel); OntClass sPhone = model.getOntClass(ns + "SmartPhone"); ExtendedIterator s = sPhone.listInstances(); while(s.hasNext()) { OntResource mp = (OntResource)s.next(); System.out.println(mp.getURI()); } This code works perfectly and returns me the instances, but when I change the code below and make it appropriate for CheapPhone, it doesn't return anything. OntClass sPhone = model.getOntClass(ns + "CheapPhone"); Am I doing something wrong ?

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  • Travelling Salesman Problem Constraint Representation

    - by alex25
    Hey! I read a couple of articles and sample code about how to solve TSP with Genetic Algorithms and Ant Colony Optimization etc. But everything I found didn't include time (window) constraints, eg. "I have to be at customer x before 12am)" and assumed symmetry. Can somebody point me into the direction of some sample code or articles that explain how I can add constraints to TSP and how I can represent those in code. Thanks!

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  • mysql ignores not null constraint?

    - by Marga Keuvelaar
    I have created a table with NOT NULL constraints on some columns in MySQL. Then in PHP I wrote a script to insert data, with an insert query. When I omit one of the NOT NULL columns in this insert statement I would expect an error message from MySQL, and I would expect my script to fail. Instead, MySQL inserts empty strings in the NOT NULL fields. In other omitted fields the data is NULL, which is fine. Could someone tell me what I did wrong here? I'm using this table: CREATE TABLE IF NOT EXISTS tblCustomers ( cust_id int(11) NOT NULL AUTO_INCREMENT, custname varchar(50) NOT NULL, company varchar(50), phone varchar(50), email varchar(50) NOT NULL, country varchar(50) NOT NULL, ... date_added timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, PRIMARY KEY (cust_id) ) ; And this insert statement: $sql = "INSERT INTO tblCustomers (custname,company) VALUES ('".$customerName."','".$_POST["CustomerCompany"]."')"; $res = mysqli_query($mysqli, $sql);

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  • Constraint to array dimension in C language

    - by Summer_More_More_Tea
    int KMP( const char *original, int o_len, const char *substring, int s_len ){ if( o_len < s_len ) return -1; int k = 0; int cur = 1; int fail[ s_len ]; fail[ k ] = -1; while( cur < s_len ){ k = cur - 1; do{ if( substring[ cur ] == substring[ k ] ){ fail[ cur ] = k; break; }else{ k = fail[ k ] + 1; } }while( k ); if( !k && ( substring[ cur ] != substring[ 0 ] ) ){ fail[ cur ] = -1; }else if( !k ){ fail[ cur ] = 0; } cur++; } k = 0; cur = 0; while( ( k < s_len ) && ( cur < o_len ) ){ if( original[ cur ] == substring[ k ] ){ cur++; k++; }else{ if( k == 0 ){ cur++; }else{ k = fail[ k - 1 ] + 1; } } } if( k == s_len ) return cur - k; else return -1; } This is a KMP algorithm I once coded. When I reviewed it this morning, I find it strange that an integer array is defined as int fail[ s_len ]. Does the specification requires dimesion of arrays compile-time constant? How can this code pass the compilation? By the way, my gcc version is 4.4.1. Thanks in advance!

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  • Python combinations no repeat by constraint

    - by user2758113
    I have a tuple of tuples (Name, val 1, val 2, Class) tuple = (("Jackson",10,12,"A"), ("Ryan",10,20,"A"), ("Michael",10,12,"B"), ("Andrew",10,20,"B"), ("McKensie",10,12,"C"), ("Alex",10,20,"D")) I need to return all combinations using itertools combinations that do not repeat classes. How can I return combinations that dont repeat classes. For example, the first returned statement would be: tuple0, tuple2, tuple4, tuple5 and so on.

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  • Consolidating values in a junction table

    - by senloe
    I have the following schema: Parcels Segments SegmentsParcels ========= ========== ================= ParcelID SegmentID ParcelID ... Name SegmentID ... id A user of the data wants to consolidate Segments.Names and gave me a list of current Segment.Names mapped to new Segment.Names (all of which currently exist). So now I have this list in a temporary table with the currentID and newID to map to. What I want to do is update the SegmentID in SegmentsParcels based on this map. I could use the statement: update SegmentParcels set segmentID = [newID] from newsegments where segmentID = currentid but this will create some duplicates I have a unique constraint on ParcelID and SegmentID in SegmentParcels. What is the best way to go about this? I considered removing the constraint and then dealing with removing the duplicates (which I did at one point and could probably do again) but I was hoping there was a simpler way.

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  • Violation of primary key constraint, multiple users

    - by MC.
    Lets say UserA and UserB both have an application open and are working with the same type of data. UserA inserts a record into the table with value 10 (PrimaryKey='A'), UserB does not currently see the value UserA entered and attempts to insert a new value of 20 (PrimaryKey='A'). What I wanted in this situation was a DBConcurrencyException, but instead what I have is a primary key violation. I understand why, but I have no idea how to resolve this. What is a good practice to deal with such a circumstance? I do not want to merge before updating the database because I want an error to inform the user that multiple users updated this data.

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  • Grails: Duplicates & unique constraint validation

    - by rukoche
    OK here is stripped down version of what I have in my app Artist domain: class Artist { String name Date lastMined def artistService static transients = ['artistService'] static hasMany = [events: Event] static constraints = { name(unique: true) lastMined(nullable: true) } def mine() { artistService.mine(this) } } Event domain: class Event { String name String details String country String town String place String url String date static belongsTo = [Artist] static hasMany = [artists: Artist] static constraints = { name(unique: true) url(unique: true) } } ArtistService: class ArtistService { def results = [ [ name:"name", details:"details", country:"country", town:"town", place:"place", url:"url", date:"date" ] ] def mine(Artist artist) { results << results[0] // now we have a duplicate results.each { def event = new Event(it) if (event.validate()) { if (artist.events.find{ it.name == event.name }) { log.info "grrr! valid duplicate name: ${event.name}" } artist.addToEvents(event) } } artist.lastMined = new Date() if (artist.events) { artist.save(flush: true) } } } In theory event.validate() should return false and event will not be added to artist, but it doesn't.. which results in DB exception on artist.save() Although I noticed that if duplicate event is persisted first everything works as intended. Is it bug or feature? :P

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  • Generate all permutations with sort constraint

    - by Moos Hueting
    Hi! I have a list consisting of other lists and some zeroes, for example: x = [[1, 1, 2], [1, 1, 1, 2], [1, 1, 2], 0, 0, 0] I would like to generate all the combinations of this list while keeping the order of the inner lists unchanged, so [[1, 1, 2], 0, 0, [1, 1, 1, 2], [1, 1, 2], 0] is fine, but [[1, 1, 1, 2], [1, 1, 2], 0, 0, [1, 1, 2], 0] isn't. I've got the feeling that this should be fairly easy in Python, but I just don't see it. Could somebody help me out?

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  • Oracle - Trigger to check constraint before insert

    - by user1816507
    i would like to create a simple trigger to check a stored variable from a table. if the value of the variable is '1', then approve the insertion else if the value of the variable is '2', then prompt error message. CREATE OR REPLACE TRIGGER approval BEFORE INSERT ON VIP REFERENCING OLD AS MEMBER FOR EACH ROW DECLARE CONDITION_CHECK NUMBER; BEGIN SELECT CONDITION INTO CONDITION_CHECK FROM MEMBER; IF CONDITION_CHECK = '2' THEN RAISE_APPLICATION_ERROR (-20000, ' UPGRADE DENIED!'); END IF; END; But this trigger disable all the entries even when the condition value is '1'.

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  • Shuffling a list with a constraint

    - by 500
    Preparing a new psychophysic experiment, I have 48 original stimuli displayed 4 times (4 conditions). Resulting in 192 trials. Trying to randomize the order of presentation during the experiment, I need to maximize the distance between the 4 display of the same original stimuli. Please Consider : Table[{j, i}, {j, Range[48]}, {i, Range[4]}] Where j is the original stimuli number and i the condition Output Sample : {{1, 1}, {1, 2}, {1, 3}, {1, 4}, {2, 1}, {2, 2}, {2, 3}, {2, 4}, ... {47, 1}, {47, 2}, {47, 3},{47, 4}, {48, 1}, {48, 2}, {48, 3}, {48, 4}} How could I shuffle the order of presentation of those 192 items, maximizing the distance between identical item with regard to j the original stimuli number ?

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  • Check constraint on table lookup

    - by bzamfir
    Hi, I have a table, department , with several bit fields to indicate department types One is Warehouse (when true, indicate the department is warehouse) And I have another table, ManagersForWarehouses with following structure: ID autoinc WarehouseID int (foreign key reference DepartmentID from departments) ManagerID int (foreign key reference EmployeeID from employees) StartDate EndDate To set new manager for warehouse, I insert in this table with EndDate null, and I have a trigger that sets EndDate for previous record for that warehouse = StartDate for new manager, so a single manager appears for a warehouse at a certain time. I want to add two check constraints as follows, but not sure how to do this do not allow to insert into ManagersForWarehouses if WarehouseID is not marked as warehouse Do not allow to uncheck Warehouse if there are records in ManagersForWarehouses Thanks

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  • Why isn't the new() generic constraint satisfied by a class with optional parameters in the construc

    - by Joshua Flanagan
    The following code fails to compile, producing a "Widget must be a non-abstract type with a public parameterless constructor" error. I would think that the compiler has all of the information it needs. Is this a bug? An oversight? Or is there some scenario where this would not be valid? public class Factory<T> where T : new() { public T Build() { return new T(); } } public class Widget { public Widget(string name = "foo") { Name = name; } public string Name { get; set; } } public class Program { public static void Main() { var widget = new Widget(); // this is valid var factory = new Factory<Widget>(); // compiler error } }

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  • Does IE6 Really not Allow Me to set width/height from left/right/top/bottom???

    - by viatropos
    Building a site super quick and having it work on all my Mac browsers, I thought I'd take a gander on a friends old dell laptop with Windows XP and IE6. Nothing looks remotely correct. It's because I used lots of left/right/top/bottom (constraint) declarations to size elements proportionally to their parent's size (I didn't use percent sizes because the percents refer to the parent's size before margins and padding are applied, left/right/top/bottom refer to them after with position:absolute. I'm asking about that here :)). I've read lots these past few weeks on how horrible IE6 (and IE) is in general, but because of all the reasons people say to support it (large market share and the fear of installing better software), and because half the people in the company we're building a site for use IE6 (getting them to upgrade to Chrome slowly but surely), I thought if I could just get IE6 to render my constraints, that might help. So I am messing around with simple layouts here, and they work fine in my latest versions of Firefox, Safari, Chrome, and Opera, but IE6 is basically saying: If you haven't set a width or height on me, I'm assuming it's zero. But position:absolute; left:0px; right:0px; top:0px; bottom:0px; on a container that's width:1000px; height:1000px; should be the same as setting width:1000px; height:1000px on the child, no? Taking a quick look at the source for this, why won't IE6 render the constraint based absolutely positioned AND SIZED elements? (note: I will be messing around with that file for a while) Thanks

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