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  • Having to insert a record, then update the same record warrants 1:1 relationship design?

    - by dianovich
    Let's say an Order has many Line items and we're storing the total cost of an order (based on the sum of prices on order lines) in the orders table. -------------- orders -------------- id ref total_cost -------------- -------------- lines -------------- id order_id price -------------- In a simple application, the order and line are created during the same step of the checkout process. So this means INSERT INTO orders .... -- Get ID of inserted order record INSERT into lines VALUES(null, order_id, ...), ... where we get the order ID after creating the order record. The problem I'm having is trying to figure out the best way to store the total cost of an order. I don't want to have to create an order create lines on an order calculate cost on order based on lines then update record created in 1. in orders table This would mean a nullable total_cost field on orders for starters... My solution thus far is to have an order_totals table with a 1:1 relationship to the orders table. But I think it's redundant. Ideally, since everything required to calculate total costs (lines on an order) is in the database, I would work out the value every time I need it, but this is very expensive. What are your thoughts?

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  • How do I specify the foreign key on a many-to-one relationship when is not a property on the object

    - by jjujuma
    I'm trying to map a many-to-one relationship from MarketMenuBranch to Market. My classes look like: public class Market implements Serializable { private int id; private String name; private List<MarketMenuBranch> marketMenuBranches; // accessors / mutators etc... public class MarketMenuBranch implements Serializable { private MarketMenuBranchId id; private String name; // accessors / mutators etc... public class MarketMenuBranchId implements Serializable { private int marketId; private int sequence; // accessors / mutators etc... But I don't know what I can put for the property name (where I have ???? below). I really want to put id.marketId but that seems to be wrong. <class name="MarketMenuBranch" table="MARKET_MENU_BRANCH"> <composite-id name="id" class="MarketMenuBranchId"> <key-property name="marketId"/> <key-property name="sequence"/> </composite-id> <property name="name"/> <many-to-one name="????????"/> </class> How can I do this?

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  • Logic in the db for maintaining a points system relationship?

    - by MarcusBooster
    I'm making a little web based game and need to determine where to put logic that checks the integrity of some underlying data in the sql database. Each user keeps track of points assigned to him, and points are awarded by various tasks. I keep a record of each task transaction to make sure they're not repeated, and to keep track of the value of the task at the time of completion, since an individual award level my fluctuate over time. My schema looks like this so far: create table player ( player_ID serial primary key, player_Points int not null default 0 ); create table task ( task_ID serial primary key, task_PointsAwarded int not null ); create table task_list ( player_ID int references player(player_ID), task_ID int references task(task_ID), when_completed timestamp default current_timestamp, point_value int not null, --not fk because task value may change later constraint pk_player_task_id primary key (player_ID, task_ID) ); So, the player.player_Points should be the total of all his cumulative task points in the task_list. Now where do I put the logic to enforce this? Should I do away with player.player_Points altogether and do queries every time I want to know the total score? Which seems wasteful since I'll be doing that query a lot over the course of a game. Or, put a trigger in the task_list that automatically updates the player.player_Points? Is that too much logic to have in the database and should just maintain this relationship in the application? Thanks.

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  • Rails - HABTM Relationship -- How Can I Find A Record Based On An Attribute Of The Associated Model

    - by ChrisWesAllen
    I have setup this HABTM relationship in the past and its worked before....Now it isnt and I'm at my wits end trying to figure out whats wrong. I've looking through the rails guides all day and cant seem to figure out what I'm doing wrong, so help would really be appreciated. I have 2 models connected through a join model and I'm trying to find records based an attribute of the associated model. Event.rb has_and_belongs_to_many :interests Interest.rb has_and_belongs_to_many :events and a join table migration that was created like create_table 'events_interests', :id => false do |t| t.column :event_id, :integer t.column :interest_id, :integer end I tried @events = Event.all(:include => :interest, :conditions => [" interest.id = ?", 4 ] ) But got the error "Association named 'interest' was not found; perhaps you misspelled it?"... which I didnt of course I tried @events = Event.interests.find(:all, :conditions => [" interest.id = ?", 4 ] ) but got the error "undefined method `interests' for #Class:0x4383348" How can I find the Events that have an interest id of 4....I'm definitely going bald from this lol

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  • Can you configure multiple KMS hosts in a primary / secondary relationship?

    - by Mark Hall
    We have two datacenters in our environment: primary and DR. I need to deploy a KMS service, and to be proactive, I would like to have a host in both datacenters. From what I have read, you can have up to 6 hosts without calling Microsoft, and it appears that what will happen is that a SRV record for each host will be placed in DNS. The client will query for those SRV records and randomly choose a host for the initial activation and will use that same server for all renewals. The server can be changed manually through a script and will automatically change if the initial server is unavailable when activating or renewing. My question is has anyone found a way to designate one server as the primary KMS host and designate the other as failover only? The reason I ask is that it is preferred that the client communicate with the primary datacenter during normal operations and only talk to the DR datacenter when needed because the bandwidth between the offices and the DR datacenter is limited compared to the primary. I am sure that this has been done before but I can not find it MSFT's documentation. Thanks, Mark

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  • The security database on the server does not have a computer account for this workstation trust relationship

    - by alex
    I have a Server 2008 machine called OTTO I recently, by mistake, booted up an old machine, also called OTTO (the hardware was unstable, so the new one was set up to take it's place) I shut down the old machine, turned it off, and recycled it (it won't ever be back on) Now, whenever i try to log in to the real OTTO with the domain account (mydomain\Administrator) i get the following error: The security database on the server does not have a computer account for this workstation What can I do to fix this? It doesn't appear in active directory any more I've added it, but I'm guessing this had no effect, due to a different SID I can log in as the local administrator however

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  • Relationships in a Chen ERD

    - by Nibroc A Rehpotsirhc
    I am working on a Chen ERD to model our organizations merchandise. Our central entity is a Style. We have supplemental entities of Color and Season. I am defining our assortment as the relationship between these three entities, and this relationship itself will have attributes and is defined by the three entities which participate in the mandatory relationship. The rules are; Many Styles can be offered in a Season, and a Style can be offered in many Seasons. Within a Season, a Style can be offered in Many Colors. I then have 2 other entities, one of which I believe is a weak entity, Climate, and the other may be weak, but I am not sure, this being Transaction Channel. I am thinking of these as relationships off of a relationship? Meaning, for a given Style/Color combination offered in a Season, it can be available through 1 or more Transaction Channels. Additionally, within a season, a given Style/Color combination can be intended for 1 or more Climates. Is it valid to have relationships off of relationships? Or does this requirement dictate that I should think of this Style/Color/Season relationship as an entity itself, and define the relationships to Climate and Transaction Channel off of this entity?

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  • How can I achieve this kind of relationship (inheritance, composition, something else)?

    - by Tim
    I would like to set up a foundation of classes for an application, two of which are person and student. A person may or may not be a student and a student is always a person. The fact that a student “is a” person led me to try inheritance, but I can't see how to make it work in the case where I have a DAO that returns an instance of person and I then want to determine if that person is a student and call student related methods for it. class Person { private $_firstName; public function isStudent() { // figure out if this person is a student return true; // (or false) } } class Student extends Person { private $_gpa; public function getGpa() { // do something to retrieve this student's gpa return 4.0; // (or whatever it is) } } class SomeDaoThatReturnsPersonInstances { public function find() { return new Person(); } } $myPerson = SomeDaoThatReturnsPersonInstances::find(); if($myPerson->isStudent()) { echo 'My person\'s GPA is: ', $myPerson->getGpa(); } This obviously doesn't work, but what is the best way to achieve this effect? Composition doesn't sond right in my mind because a person does not “have a” student. I'm not looking for a solution necessarily but maybe just a term or phrase to search for. Since I'm not really sure what to call what I'm trying to do, I haven't had much luck. Thank you!

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  • Is a many-to-many relationship with extra fields the right tool for my job?

    - by whichhand
    Previously had a go at asking a more specific version of this question, but had trouble articulating what my question was. On reflection that made me doubt if my chosen solution was correct for the problem, so this time I will explain the problem and ask if a) I am on the right track and b) if there is a way around my current brick wall. I am currently building a web interface to enable an existing database to be interrogated by (a small number of) users. Sticking with the analogy from the docs, I have models that look something like this: class Musician(models.Model): first_name = models.CharField(max_length=50) last_name = models.CharField(max_length=50) dob = models.DateField() class Album(models.Model): artist = models.ForeignKey(Musician) name = models.CharField(max_length=100) class Instrument(models.Model): artist = models.ForeignKey(Musician) name = models.CharField(max_length=100) Where I have one central table (Musician) and several tables of associated data that are related by either ForeignKey or OneToOneFields. Users interact with the database by creating filtering criteria to select a subset of Musicians based on data the data on the main or related tables. Likewise, the users can then select what piece of data is used to rank results that are presented to them. The results are then viewed initially as a 2 dimensional table with a single row per Musician with selected data fields (or aggregates) in each column. To give you some idea of scale, the database has ~5,000 Musicians with around 20 fields of related data. Up to here is fine and I have a working implementation. However, it is important that I have the ability for a given user to upload there own annotation data sets (more than one) and then filter and order on these in the same way they can with the existing data. The way I had tried to do this was to add the models: class UserDataSets(models.Model): user = models.ForeignKey(User) name = models.CharField(max_length=100) description = models.CharField(max_length=64) results = models.ManyToManyField(Musician, through='UserData') class UserData(models.Model): artist = models.ForeignKey(Musician) dataset = models.ForeignKey(UserDataSets) score = models.IntegerField() class Meta: unique_together = (("artist", "dataset"),) I have a simple upload mechanism enabling users to upload a data set file that consists of 1 to 1 relationship between a Musician and their "score". Within a given user dataset each artist will be unique, but different datasets are independent from each other and will often contain entries for the same musician. This worked fine for displaying the data, starting from a given artist I can do something like this: artist = Musician.objects.get(pk=1) dataset = UserDataSets.objects.get(pk=5) print artist.userdata_set.get(dataset=dataset.pk) However, this approach fell over when I came to implement the filtering and ordering of query set of musicians based on the data contained in a single user data set. For example, I could easily order the query set based on all of the data in the UserData table like this: artists = Musician.objects.all().order_by(userdata__score) But that does not help me order by the results of a given single user dataset. Likewise I need to be able to filter the query set based on the "scores" from different user data sets (eg find all musicians with a score 5 in dataset1 and < 2 in dataset2). Is there a way of doing this, or am I going about the whole thing wrong?

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  • Compile error on inheritance of generic inner class extending with bounds

    - by Arne Burmeister
    I have a problem when compiling a generic class with an inner class. The class extends a generic class, the inner class also. Here the interface implemented: public interface IndexIterator<Element> extends Iterator<Element> { ... } The generic super class: public abstract class CompoundCollection<Element, Part extends Collection<Element>> implements Collection<Element> { ... protected class CompoundIterator<Iter extends Iterator<Element>> extends ImmutableIterator<Element> { ... } } The generic subclass with the compiler error: public class CompoundList<Element> extends CompoundCollection<Element, List<Element>> implements List<Element> { ... private class CompoundIndexIterator extends CompoundIterator<IndexIterator<Element>> implements IndexIterator<Element> { ... } } The error is: type parameter diergo.collect.IndexIterator<Element> is not within its bound extends CompoundIterator<IndexIterator<Element>> ^ What is wrong? The code compiles with eclipse, but bot with java 5 compiler (I use ant with java 5 on a mac and eclipse 3.5). No, I cannot convert it to a static inner class.

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  • java generics and the addAll method

    - by neesh
    What is the correct type of argument to the addAll(..) method in Java collections? If I do something like this: Collection<HashMap<String, Object[]>> addAll = new ArrayList<HashMap<String, Object[]>>(); // add some hashmaps to the list.. currentList.addAll(newElements); //currentList is of type: List<? extends Map<String, Object[]>> I understand I need to initialize both variables. However, I get a compilation error (from eclipse): Multiple markers at this line - The method addAll(Collection<? extends capture#1-of ? extends Map<String,Object[]>>) in the type List<capture#1-of ? extends Map<String,Object[]>> is not applicable for the arguments (List<capture#2-of ? extends Map<String,Object[]>>) - The method addAll(Collection<? extends capture#1-of ? extends Map<String,Object[]>>) in the type List<capture#1-of ? extends Map<String,Object[]>> is not applicable for the arguments (Collection<HashMap<String,Object[]>>) what am I doing wrong?

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  • Problem with 2 levels of inheritance in hibernate mapping

    - by Seth
    Here's my class structure: class A class B extends A class C extends A class D extends C class E extends C And here are my mappings (class bodies omitted for brevity): Class A: @Entity @Inheritance(strategy=InheritanceType.SINGLE_TABLE) @MappedSuperclass @DiscriminatorColumn( name="className", discriminatorType=DiscriminatorType.STRING ) @ForceDiscriminator public abstract class A Class B: @Entity @DiscriminatorValue("B") public class B extends A Class C: @Entity @DiscriminatorValue("C") @MappedSuperclass @DiscriminatorColumn( name="cType", discriminatorType=DiscriminatorType.STRING ) @ForceDiscriminator public abstract class C extends A Class D: @Entity @DiscriminatorValue("D") public class D extends C Class E: @Entity @DiscriminatorValue("E") public class E extends C I've got a class F that contains a set of A: @Entity public class F { ... @OneToMany(fetch=FetchType.LAZY, cascade=CascadeType.ALL) @JoinTable( name="F_A", joinColumns = @JoinColumn(name="A_ID"), inverseJoinColumns = @JoinColumn(name="F_ID") ) private Set<A> aSet = new HashSet<A>(); ... The problem is that whenever I add a new E instance to aSet and then call session.saveOrUpdate(fInstance), hibernate saves with "A" as the discrimiator string. When I try to access the aSet in the F instance, I get the following exception (full stacktrace ommitted for brevity): org.hibernate.InstantiationException: Cannot instantiate abstract class or interface: path.to.class.A Am I mapping the classes incorrectly? How am I supposed to map multiple levels of inheritance? Thanks for the help!

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  • How to Add, Edit and Display one to many relationship entities in ASP.Net MVC 2?

    - by Picflight
    I am looking for best practices conforming to the MVC design pattern. My Entities have the following relationship. tblPortal PortalId PrortalName tblPortalAlias AliasId PortalId HttpAlias Each Portal can have many PortalAlias. I want to Add a New Portal and then Add the associated PortalAlias. I am confused on how I should structure the Views and how I should present the Views to the user. I am looking for some sample code on how to accomplish this. My thoughts are first present the Portal View, let the user add the Portal. Then click the Edit link on the Portal List View and on the Portal Edit View let them Add the PortalAlias. If so, what should the Edit View look like? So far I have: Edit <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<MyProject.Mvc.Models.PortalFormViewModel>" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server"> Edit </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <h2>Edit</h2> <% Html.RenderPartial("PortalForm", Model); %> <div> <%= Html.ActionLink("Back to List", "Index") %> </div> </asp:Content> PortalForm <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<MyProject.Mvc.Models.PortalFormViewModel>" %> <%= Html.ValidationSummary("Please correct the errors and try again.") %> <% using (Html.BeginForm()) {%> <%= Html.ValidationSummary(true) %> <fieldset> <legend>Fields</legend> <div class="editor-label"> <%= Html.LabelFor(model => model.Portal.PortalId) %> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Portal.PortalId) %> <%= Html.ValidationMessageFor(model => model.Portal.PortalId) %> </div> <div class="editor-label"> <%= Html.LabelFor(model => model.Portal.PortalName) %> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Portal.PortalName) %> <%= Html.ValidationMessageFor(model => model.Portal.PortalName) %> </div> <p> <input type="submit" value="Save" /> </p> </fieldset> <% } %> Alias<br /><%-- This display is for debug --%> <% foreach (var item in Model.PortalAlias) { %> <%= item.HTTPAlias %><br /> <% } %> PortalFormViewModel public class PortalFormViewModel { public Portal Portal { get; private set; } public IEnumerable<PortalAlias> PortalAlias { get; private set; } public PortalFormViewModel() { Portal = new Portal(); } public PortalFormViewModel(Portal portal) { Portal = portal; PortalAlias = portal.PortalAlias; } }

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  • Self-type mismatch in Scala

    - by Alexey Romanov
    Given this: abstract class ViewPresenterPair { type V <: View type P <: Presenter trait View {self: V => val presenter: P } trait Presenter {self: P => var view: V } } I am trying to define an implementation in this way: case class SensorViewPresenter[T] extends ViewPresenterPair { type V = SensorView[T] type P = SensorPresenter[T] trait SensorView[T] extends View { } class SensorViewImpl[T](val presenter: P) extends SensorView[T] { presenter.view = this } class SensorPresenter[T] extends Presenter { var view: V } } Which gives me the following errors: error: illegal inheritance; self-type SensorViewPresenter.this.SensorView[T] does not conform to SensorViewPresenter.this.View's selftype SensorViewPresenter.this.V trait SensorView[T] extends View { ^ <console>:13: error: type mismatch; found : SensorViewPresenter.this.SensorViewImpl[T] required: SensorViewPresenter.this.V presenter.view = this ^ <console>:16: error: illegal inheritance; self-type SensorViewPresenter.this.SensorPresenter[T] does not conform to SensorViewPresenter.this.Presenter's selftype SensorViewPresenter.this.P class SensorPresenter[T] extends Presenter { ^ I don't understand why. After all, V is just an alias for SensorView[T], and the paths are the same, so how can it not conform?

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  • LLBLGen Pro feature highlights: automatic element name construction

    - by FransBouma
    (This post is part of a series of posts about features of the LLBLGen Pro system) One of the things one might take for granted but which has a huge impact on the time spent in an entity modeling environment is the way the system creates names for elements out of the information provided, in short: automatic element name construction. Element names are created in both directions of modeling: database first and model first and the more names the system can create for you without you having to rename them, the better. LLBLGen Pro has a rich, fine grained system for creating element names out of the meta-data available, which I'll describe more in detail below. First the model element related element naming features are highlighted, in the section Automatic model element naming features and after that I'll go more into detail about the relational model element naming features LLBLGen Pro has to offer in the section Automatic relational model element naming features. Automatic model element naming features When working database first, the element names in the model, e.g. entity names, entity field names and so on, are in general determined from the relational model element (e.g. table, table field) they're mapped on, as the model elements are reverse engineered from these relational model elements. It doesn't take rocket science to automatically name an entity Customer if the entity was created after reverse engineering a table named Customer. It gets a little trickier when the entity which was created by reverse engineering a table called TBL_ORDER_LINES has to be named 'OrderLine' automatically. Automatic model element naming also takes into effect with model first development, where some settings are used to provide you with a default name, e.g. in the case of navigator name creation when you create a new relationship. The features below are available to you in the Project Settings. Open Project Settings on a loaded project and navigate to Conventions -> Element Name Construction. Strippers! The above example 'TBL_ORDER_LINES' shows that some parts of the table name might not be needed for name creation, in this case the 'TBL_' prefix. Some 'brilliant' DBAs even add suffixes to table names, fragments you might not want to appear in the entity names. LLBLGen Pro offers you to define both prefix and suffix fragments to strip off of table, view, stored procedure, parameter, table field and view field names. In the example above, the fragment 'TBL_' is a good candidate for such a strip pattern. You can specify more than one pattern for e.g. the table prefix strip pattern, so even a really messy schema can still be used to produce clean names. Underscores Be Gone Another thing you might get rid of are underscores. After all, most naming schemes for entities and their classes use PasCal casing rules and don't allow for underscores to appear. LLBLGen Pro can automatically strip out underscores for you. It's an optional feature, so if you like the underscores, you're not forced to see them go: LLBLGen Pro will leave them alone when ordered to to so. PasCal everywhere... or not, your call LLBLGen Pro can automatically PasCal case names on word breaks. It determines word breaks in a couple of ways: a space marks a word break, an underscore marks a word break and a case difference marks a word break. It will remove spaces in all cases, and based on the underscore removal setting, keep or remove the underscores, and upper-case the first character of a word break fragment, and lower case the rest. Say, we keep the defaults, which is remove underscores and PasCal case always and strip the TBL_ fragment, we get with our example TBL_ORDER_LINES, after stripping TBL_ from the table name two word fragments: ORDER and LINES. The underscores are removed, the first character of each fragment is upper-cased, the rest lower-cased, so this results in OrderLines. Almost there! Pluralization and Singularization In general entity names are singular, like Customer or OrderLine so LLBLGen Pro offers a way to singularize the names. This will convert OrderLines, the result we got after the PasCal casing functionality, into OrderLine, exactly what we're after. Show me the patterns! There are other situations in which you want more flexibility. Say, you have an entity Customer and an entity Order and there's a foreign key constraint defined from the target of Order and the target of Customer. This foreign key constraint results in a 1:n relationship between the entities Customer and Order. A relationship has navigators mapped onto the relationship in both entities the relationship is between. For this particular relationship we'd like to have Customer as navigator in Order and Orders as navigator in Customer, so the relationship becomes Customer.Orders 1:n Order.Customer. To control the naming of these navigators for the various relationship types, LLBLGen Pro defines a set of patterns which allow you, using macros, to define how the auto-created navigator names will look like. For example, if you rather have Customer.OrderCollection, you can do so, by changing the pattern from {$EndEntityName$P} to {$EndEntityName}Collection. The $P directive makes sure the name is pluralized, which is not what you want if you're going for <EntityName>Collection, hence it's removed. When working model first, it's a given you'll create foreign key fields along the way when you define relationships. For example, you've defined two entities: Customer and Order, and they have their fields setup properly. Now you want to define a relationship between them. This will automatically create a foreign key field in the Order entity, which reflects the value of the PK field in Customer. (No worries if you hate the foreign key fields in your classes, on NHibernate and EF these can be hidden in the generated code if you want to). A specific pattern is available for you to direct LLBLGen Pro how to name this foreign key field. For example, if all your entities have Id as PK field, you might want to have a different name than Id as foreign key field. In our Customer - Order example, you might want to have CustomerId instead as foreign key name in Order. The pattern for foreign key fields gives you that freedom. Abbreviations... make sense of OrdNr and friends I already described word breaks in the PasCal casing paragraph, how they're used for the PasCal casing in the constructed name. Word breaks are used for another neat feature LLBLGen Pro has to offer: abbreviation support. Burt, your friendly DBA in the dungeons below the office has a hate-hate relationship with his keyboard: he can't stand it: typing is something he avoids like the plague. This has resulted in tables and fields which have names which are very short, but also very unreadable. Example: our TBL_ORDER_LINES example has a lovely field called ORD_NR. What you would like to see in your fancy new OrderLine entity mapped onto this table is a field called OrderNumber, not a field called OrdNr. What you also like is to not have to rename that field manually. There are better things to do with your time, after all. LLBLGen Pro has you covered. All it takes is to define some abbreviation - full word pairs and during reverse engineering model elements from tables/views, LLBLGen Pro will take care of the rest. For the ORD_NR field, you need two values: ORD as abbreviation and Order as full word, and NR as abbreviation and Number as full word. LLBLGen Pro will now convert every word fragment found with the word breaks which matches an abbreviation to the given full word. They're case sensitive and can be found in the Project Settings: Navigate to Conventions -> Element Name Construction -> Abbreviations. Automatic relational model element naming features Not everyone works database first: it may very well be the case you start from scratch, or have to add additional tables to an existing database. For these situations, it's key you have the flexibility that you can control the created table names and table fields without any work: let the designer create these names based on the entity model you defined and a set of rules. LLBLGen Pro offers several features in this area, which are described in more detail below. These features are found in Project Settings: navigate to Conventions -> Model First Development. Underscores, welcome back! Not every database is case insensitive, and not every organization requires PasCal cased table/field names, some demand all lower or all uppercase names with underscores at word breaks. Say you create an entity model with an entity called OrderLine. You work with Oracle and your organization requires underscores at word breaks: a table created from OrderLine should be called ORDER_LINE. LLBLGen Pro allows you to do that: with a simple checkbox you can order LLBLGen Pro to insert an underscore at each word break for the type of database you're working with: case sensitive or case insensitive. Checking the checkbox Insert underscore at word break case insensitive dbs will let LLBLGen Pro create a table from the entity called Order_Line. Half-way there, as there are still lower case characters there and you need all caps. No worries, see below Casing directives so everyone can sleep well at night For case sensitive databases and case insensitive databases there is one setting for each of them which controls the casing of the name created from a model element (e.g. a table created from an entity definition using the auto-mapping feature). The settings can have the following values: AsProjectElement, AllUpperCase or AllLowerCase. AsProjectElement is the default, and it keeps the casing as-is. In our example, we need to get all upper case characters, so we select AllUpperCase for the setting for case sensitive databases. This will produce the name ORDER_LINE. Sequence naming after a pattern Some databases support sequences, and using model-first development it's key to have sequences, when needed, to be created automatically and if possible using a name which shows where they're used. Say you have an entity Order and you want to have the PK values be created by the database using a sequence. The database you're using supports sequences (e.g. Oracle) and as you want all numeric PK fields to be sequenced, you have enabled this by the setting Auto assign sequences to integer pks. When you're using LLBLGen Pro's auto-map feature, to create new tables and constraints from the model, it will create a new table, ORDER, based on your settings I previously discussed above, with a PK field ID and it also creates a sequence, SEQ_ORDER, which is auto-assigns to the ID field mapping. The name of the sequence is created by using a pattern, defined in the Model First Development setting Sequence pattern, which uses plain text and macros like with the other patterns previously discussed. Grouping and schemas When you start from scratch, and you're working model first, the tables created by LLBLGen Pro will be in a catalog and / or schema created by LLBLGen Pro as well. If you use LLBLGen Pro's grouping feature, which allows you to group entities and other model elements into groups in the project (described in a future blog post), you might want to have that group name reflected in the schema name the targets of the model elements are in. Say you have a model with a group CRM and a group HRM, both with entities unique for these groups, e.g. Employee in HRM, Customer in CRM. When auto-mapping this model to create tables, you might want to have the table created for Employee in the HRM schema but the table created for Customer in the CRM schema. LLBLGen Pro will do just that when you check the setting Set schema name after group name to true (default). This gives you total control over where what is placed in the database from your model. But I want plural table names... and TBL_ prefixes! For now we follow best practices which suggest singular table names and no prefixes/suffixes for names. Of course that won't keep everyone happy, so we're looking into making it possible to have that in a future version. Conclusion LLBLGen Pro offers a variety of options to let the modeling system do as much work for you as possible. Hopefully you enjoyed this little highlight post and that it has given you new insights in the smaller features available to you in LLBLGen Pro, ones you might not have thought off in the first place. Enjoy!

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  • Core Data - JSON (TouchJSON) on iPhone

    - by Urizen
    I have the following code which seems to go on indefinitely until the app crashes. It seems to happen with the recursion in the datastructureFromManagedObject method. I suspect that this method: 1) looks at the first managed object and follows any relationship property recursively. 2) examines the object at the other end of the relationship found at point 1 and repeats the process. Is it possible that if managed object A has a to-many relationship with object B and that relationship is two-way (i.e an inverse to-one relationship to A from B - e.g. one department has many employees but each employee has only one department) that the following code gets stuck in infinite recursion as it follows the to-one relationship from object B back to object A and so on. If so, can anyone provide a fix for this so that I can get my whole object graph of managed objects converted to JSON. #import "JSONUtils.h" @implementation JSONUtils - (NSDictionary*)dataStructureFromManagedObject:(NSManagedObject *)managedObject { NSDictionary *attributesByName = [[managedObject entity] attributesByName]; NSDictionary *relationshipsByName = [[managedObject entity] relationshipsByName]; //getting the values correspoinding to the attributes collected in attributesByName NSMutableDictionary *valuesDictionary = [[managedObject dictionaryWithValuesForKeys:[attributesByName allKeys]] mutableCopy]; //sets the name for the entity being encoded to JSON [valuesDictionary setObject:[[managedObject entity] name] forKey:@"ManagedObjectName"]; NSLog(@"+++++++++++++++++> before the for loop"); //looks at each relationship for the given managed object for (NSString *relationshipName in [relationshipsByName allKeys]) { NSLog(@"The relationship name = %@",relationshipName); NSRelationshipDescription *description = [relationshipsByName objectForKey:relationshipName]; if (![description isToMany]) { NSLog(@"The relationship is NOT TO MANY!"); [valuesDictionary setObject:[self dataStructureFromManagedObject:[managedObject valueForKey:relationshipName]] forKey:relationshipName]; continue; } NSSet *relationshipObjects = [managedObject valueForKey:relationshipName]; NSMutableArray *relationshipArray = [[NSMutableArray alloc] init]; for (NSManagedObject *relationshipObject in relationshipObjects) { [relationshipArray addObject:[self dataStructureFromManagedObject:relationshipObject]]; } [valuesDictionary setObject:relationshipArray forKey:relationshipName]; } return [valuesDictionary autorelease]; } - (NSArray*)dataStructuresFromManagedObjects:(NSArray*)managedObjects { NSMutableArray *dataArray = [[NSArray alloc] init]; for (NSManagedObject *managedObject in managedObjects) { [dataArray addObject:[self dataStructureFromManagedObject:managedObject]]; } return [dataArray autorelease]; } //method to call for obtaining JSON structure - i.e. public interface to this class - (NSString*)jsonStructureFromManagedObjects:(NSArray*)managedObjects { NSLog(@"-------------> just before running the recursive method"); NSArray *objectsArray = [self dataStructuresFromManagedObjects:managedObjects]; NSLog(@"-------------> just before running the serialiser"); NSString *jsonString = [[CJSONSerializer serializer] serializeArray:objectsArray]; return jsonString; } - (NSManagedObject*)managedObjectFromStructure:(NSDictionary*)structureDictionary withManagedObjectContext:(NSManagedObjectContext*)moc { NSString *objectName = [structureDictionary objectForKey:@"ManagedObjectName"]; NSManagedObject *managedObject = [NSEntityDescription insertNewObjectForEntityForName:objectName inManagedObjectContext:moc]; [managedObject setValuesForKeysWithDictionary:structureDictionary]; for (NSString *relationshipName in [[[managedObject entity] relationshipsByName] allKeys]) { NSRelationshipDescription *description = [[[managedObject entity]relationshipsByName] objectForKey:relationshipName]; if (![description isToMany]) { NSDictionary *childStructureDictionary = [structureDictionary objectForKey:relationshipName]; NSManagedObject *childObject = [self managedObjectFromStructure:childStructureDictionary withManagedObjectContext:moc]; [managedObject setValue:childObject forKey:relationshipName]; continue; } NSMutableSet *relationshipSet = [managedObject mutableSetValueForKey:relationshipName]; NSArray *relationshipArray = [structureDictionary objectForKey:relationshipName]; for (NSDictionary *childStructureDictionary in relationshipArray) { NSManagedObject *childObject = [self managedObjectFromStructure:childStructureDictionary withManagedObjectContext:moc]; [relationshipSet addObject:childObject]; } } return managedObject; } //method to call for obtaining managed objects from JSON structure - i.e. public interface to this class - (NSArray*)managedObjectsFromJSONStructure:(NSString *)json withManagedObjectContext:(NSManagedObjectContext*)moc { NSError *error = nil; NSArray *structureArray = [[CJSONDeserializer deserializer] deserializeAsArray:[json dataUsingEncoding:NSUTF32BigEndianStringEncoding] error:&error]; NSAssert2(error == nil, @"Failed to deserialize\n%@\n%@", [error localizedDescription], json); NSMutableArray *objectArray = [[NSMutableArray alloc] init]; for (NSDictionary *structureDictionary in structureArray) { [objectArray addObject:[self managedObjectFromStructure:structureDictionary withManagedObjectContext:moc]]; } return [objectArray autorelease]; } @end

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  • What is the relationship between Turing Machine & Modern Computer ? [closed]

    - by smwikipedia
    I heard a lot that modern computers are based on Turing machine. I just cannot build a bridge between a conceptual Turing Machine and a modern computer. Could someone help me build this bridge? Below is my current understanding. I think the computer is a big general-purpose Turing machine. Each program we write is a small specific-purpose Turing machine. The classical Turing machine do its job based on the input and its current state inside and so do our programs. Let's take a running program (a process) as an example. We know that in the process's address space, there's areas for stack, heap, and code. A classical Turing machine doesn't have the ability to remember many things, so we borrow the concept of stack from the push-down automaton. The heap and stack areas contains the state of our specific-purpose Turing machine (our program). The code area represents the logic of this small Turing machine. And various I/O devices supply input to this Turing machine.

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  • Can Django admin handle a one-to-many relationship via related_name?

    - by Mat
    The Django admin happily supports many-to-one and many-to-many relationships through an HTML <SELECT> form field, allowing selection of one or many options respectively. There's even a nice Javascript filter_horizontal widget to help. I'm trying to do the same from the one-to-many side through related_name. I don't see how it's much different from many-to-many as far as displaying it in the form is concerned, I just need a multi-select SELECT list. But I cannot simply add the related_name value to my ModelAdmin-derived field list. Does Django support one-to-many fields in this way? My Django model something like this (contrived to simplify the example): class Person(models.Model): ... manager = models.ForeignKey('self', related_name='staff', null=True, blank=True, ) From the Person admin page, I can easily get a <SELECT> list showing all possible staff to choose this person's manager from. I also want to display a multiple-selection <SELECT> list of all the manager's staff. I don't want to use inlines, as I don't want to edit the subordinates details; I do want to be able to add/remove people from the list. (I'm trying to use django-ajax-selects to replace the SELECT widget, but that's by-the-by.)

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  • What is the relationship between Turing Machine & Modern Computer ?

    - by smwikipedia
    I heard a lot that modern computers are based on Turing machine. I just cannot build a bridge from a conceptual Turing Machine to a real modern computer. Could someone help me build this bridge? Below is my current understanding. I think the computer is a big general-purpose Turing machine. Each program we write is a small specific-purpose Turing machine. The classical Turing machine do its job based on the input and its current state inside and so do our programs. Let's take a running program (a process) as an example. We know that in the process's address space, there's areas for stack, heap, and code. A classical Turing machine doesn't have the ability to remember many things, so we borrow the concept of stack from the push-down automaton. The heap and stack areas contains the state of our specific-purpose Turing machine (our program). The code area represents the logic of this small Turing machine. And various I/O devices supply input to this Turing machine.

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  • What is the relationship between WebProxy & IWebProxy with respect to WebClient?

    - by Streamline
    I am creating an app (.NET 2.0) that uses WebClient to connect (downloaddata, etc) to/from a http web service. I am adding a form now to handle allowing proxy information to either be stored or set to use the defaults. I am a little confused about some things. First, some of the methods & properties available in either WebProxy or IWebProxy are not in both. What is the difference here with respect to setting up how WebClient will be have when it is called? Secondly, do I have to tell WebClient to use the proxy information if I set it using either WebProxy or IWebProxy class elsewhere? Or is it automatically inherited? Thirdly, when giving the option for the user to use the default proxy (whatever is set in IE) and using the default credentials (I assume also whatever is set in IE) are these two mutually exclusive? Or you only use default credentials when you have also used default proxy? This gets me to the whole difference between WebProxy and IWebProxy. WebRequest.DefaultProxy is a IWebPRoxy class but UseDefaultCredentials is not a method on the IWebProxy class, rather it is only on WebProxy and in turn, How to set the proxy to the WebRequest.DefautlProxy if they are two different classes? Here is my current method to read the stored form settings by the user - but I am not sure if this is correct, not enough, overkill, or just wrong because of the mix of WebProxy and IWebProxy: private WebProxy _proxyInfo = new WebProxy(); private WebProxy SetProxyInfo() { if (UseProxy) { if (UseIEProxy) { // is doing this enough to set this as default for WebClient? IWebProxy iProxy = WebRequest.DefaultWebProxy; if (UseIEProxyCredentials) { _proxyInfo.UseDefaultCredentials = true; } else { // is doing this enough to set this as default credentials for WebClient? WebRequest.DefaultWebProxy.Credentials = new NetworkCredential(ProxyUsername, ProxyPassword); } } else { // is doing this enough to set this as default for WebClient? WebRequest.DefaultWebProxy = new WebProxy(ProxyAddress, ParseLib.StringToInt(ProxyPort)); if (UseIEProxyCredentials) { _proxyInfo.UseDefaultCredentials = true; } else { WebRequest.DefaultWebProxy.Credentials = new NetworkCredential(ProxyUsername, ProxyPassword); } } } // Do I need to WebClient to absorb this returned proxy info if I didn't set or use defaults? return _proxyInfo; } Is there any reason to not just scrap storing app specific proxy information and only allow the app the ability to use the default proxy information & credentials for the logged in user? Will this ever not be enough if using HTTP? Part 2 Question: How can I test that the WebClient instance is using the proxy information or not?

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  • How can I map one to one relationship in Fluent NHibernate. I have tried everything else

    - by RM
    I have this table structure and would like to map it using Fluent Hibernate (subclass if possible). I cannot change the structure because the database has too many records and might cause major applications rework. It would be easier if the Id from Party table was a foreign key in person and organization table, but in the particular scenario the database has person and organization key as a foreign key in party table. Any help would be great. Party table Id PersonId OrganizationId Person table Id FName LName Organization table Id OrgName OrgDescription

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  • How to make linq master detail query for 0..n relationship?

    - by JK
    Given a classic DB structure of Orders has zero or more OrderLines and OrderLine has exactly one Product, how do I write a linq query to express this? The output would be OrderNumber - OrderLine - Product Name Order-1 null null // (this order has no lines) Order-2 1 Red widget I tried this query but is not getting the orders with no lines var model = (from po in Orders from line in po.OrderLines select new { OrderNumber = po.Id, OrderLine = line.LineNumber, ProductName = line.Product.ProductDescription, } ) I think that the 2nd from is limiting the query to only those that have OrderLines, but I dont know another way to express it. LINQ is very non-obvious if you ask me!

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