relationships

问题 My Hibernate schema has a Port entity. Each Port should have zero or one connections to another Port so there is a "connectedPort" field referencing the same entity: public class Port { // ... @OneToOne @JoinColumn private Port connectedPort; // ... } But normally for a @OneToOne there would be an "owned" side of the relationship and a "mapped" side of the relationship - is this also the case here - and if so, how and why? 回答1: From the OneToOne API doc: If the relationship is bidirectional,

问题 Sorry if the description is poor, but I don't know how else to put this... But here is an example of the XML structure <?xml version=”1.0” encoding=”UTF-8”> <Response xmlns="http://www.blah.com"> <searchResult> <info> <firstName>John</firstName> <lastName>Doe</lastName> <totalCharges>100.00</totalCharges> <nonPaymentCode>99999</nonPaymentCode> </info> <info> <firstName>Susan</firstName> <lastName>Doe</lastName> <totalCharges>1000.00</totalCharges> <errorCodes> <errorCode>12345</errorCode> <

问题 I have created an asp.NET MVC web app with two models using EF Code First which have a 1-to-0..1 relationship. public class ClassA { public int Id {get;set;} //other properties public virtual ClassB ClassB {get;set;} } public class ClassB { public int Id {get;set;} //other properties } In my database, this successfully creates the two tables with ClassA having a Nullable FK for ClassB. This works great, except for the scenario in which a ClassA record is deleted. In that case, any associated

问题 Good morning, I am having a little trouble with model relationships in Eloquent, I need to link articles and images for those articles with an intermediate table. In the intermediate table I'd like to add the id's of both article and image, and I would like to retrieve all the images belonging to an article, what would be the best way to manage the relationship? Thanks in advance 回答1: You can use morphMany() relationship (Polymorphic Relationship) to solve your problem like this: UPDATE : The

问题 I have a Core Data Model with three entities: Transaction, Occasion, Person and when I'm currently fetching in the Transaction Entity, I am getting "NULL" as the value in the database. Let me explain. Transaction is in my case, the Entity that has relationships to Person and Occasion. The person entity has a name attribute and a relationship to the transaction entity. transactions (Person Entity) < ------ >> whoBy (Transaction entity). There is also a relationship from the categories

问题 I am using Neo4j 1.9 M03 in HA mode, my challenge is to remove all nodes and relationships as well as indices that are older than a certain date. For this I created a property for nodes and relationships. The property is a datestamp in the "YYMMDD" format. I'm trying to use the following Cypher query to perform the operation mentioned above: START n0=node(0), nx=node(*) MATCH n0-[r0?]-(), nx-[rx?]-() WHERE nx <> n0 AND HAS (nx.datestamp) AND nx.datestamp <= yyyymmdd OR HAS (rx.datestamp) AND

问题 I have a seemingly stupid and crazy situation. I have activity logs for users, my user model has this relationship in it: public function activityLogs() { return $this->hasMany(Log::class); } Pretty straight forward and when I check a single user object for all logs it works fine. So on one page I only want the last log recorded, I need the created_at date from it. When loading the users I run $users = User::with( [ 'activityLogs' => function ($query) { $query->orderBy('created_at', 'desc') -

问题 I have a graph database that is modeling the metadata for messages and the fields that can be contained on those messages. Some of those fields can be "groups" which are groups of other fields. What I am attempting to ask Neo is "what messages are using this group?". The following is a list of the path types that can be used to get from a message to a group: message-[:INLINE]->group (the fields of a group are used inline on a message) message-[:FIELDREF]->(fref)-[:FIELD]->(field)-[:DATATYPE]-

问题 I have the following database scheme: table 'products' id category_id and of course a category table, just with an id. The data look something like that: Products -------------------- | id | category_id | -------------------- | 0 | 1 | | 1 | 1 | | 2 | 1 | | 3 | 2 | | 4 | 2 | | 5 | 1 | -------------------- I would like to select a category(for example Category 1), so I select all the rows from that category in my product-repository class: return $this ->createQueryBuilder('u') ->andWhere('u

问题 I'm building an app that requires a core data relationship as such: entityA <<---> entityB (e.g. any given entityA can hold many entityB objects) I have two tableviews with entityA list items in which I want to be able to store entityB objects in any given entityA object. I'm new to using relationships with core data (and fairly new to swift) and would like to learn how to make this work. Does anyone have any swift tutorials in mind that would be good for me to take a look at or any other