I'm just copy & pasting some of the introductory text from one of my questions, since the same table relationship is involved in this question also.
I have three of many tables in Oracle (10g) database as listed below. I'm using Hibernate Tools 3.2.1.GA with Spring version 3.0.2.
Product - parent table
Colour - parent table
ProductColour - join table - references colourId and prodId of Colour and Product tables respectively
Where the table ProductColour is a join table between Product and Colour. As the table names imply, there is a many-to-many relationship between Product and Colour which is mapped by PrductColour. I think, the relationship in the database can easily be imagined and is clear with only this much information. Therefore, I'm not going to explore this relationship at length unnecessarily.
An entity (row) in Product is associated with any number entities in Colour and an entity (row) in Colour can also be associated with any number of entities in Product.
Since, it is a many-to-many relationship, it is mapped in the Product and the Colour entity classes (POJOs) with their respective java.util.Set and no direct POJO class for the product_colour table is available.
The class Product looks like the following.
public class Product implements java.io.Serializable
{
private BigDecimal prodId;
private Set<Colour> colours = new HashSet<Colour>(0);
.
.
.
//Other properties with setters and getters.
}
The class Colour looks like the following.
public class Colour implements java.io.Serializable
{
private BigDecimal colourId;
private Set<Product> products = new HashSet<Product>(0);
.
.
.
//Other properties with setters and getters.
}
The actual mapping between entities is available in xxx.hbm.xml files, regarding this question which is unnecessary, I think .
What I want to do is to retrieve only those rows from the Colour table which don't match the colour rows in the ProductColour table for a particular product at a time. In this regard, the native Oracle SQL statement would look something like the following.
SELECT colour_id, colour_name, colour_hex
FROM colour
WHERE colour_id not in (SELECT colour_id FROM product_colour WHERE prod_id=81)
ORDER BY colour_id DESC
Where prod_id can be any valid BigDecimal number in Java which is dynamic.
As noted earlier, the relationship is available as a many-to-many relationship in Hibernate, no POJO class for the database table product_colour is available and therefore, I'm fumbling in writing such an HQL statement in Hibernate. I have tried to write such an HQL statement but no attempts were succeeded.
[The code presented in the rest of the part may completely be unnecessary to review]
I'm therefore following a traditional way. What I'm doing is... I'm first retrieving a single product row from the Product the entity class based on a dynamic value of prodId such as,
List<Product>list=session.createQuery("from Product where prodId=:prodId")
.setParameter("prodId", prodId).list();
and then using a loop, I'm getting the entire Colour set - java.util.Set corresponding to the product_colour table in Oracle which is available in the Product entity for this product such as,
Set<Colour>colours=new HashSet<Colour>(0);
for(Product p:list)
{
if(p!=null)
{
colours=p.getColours();
}
}
As can be seen, the colours Set is being populated with all of the colour rows available (reference rows) in the product_colour table in Oracle.
After getting all of these rows, I'm getting the entire Colour entity class itself (all the row in it) that corresponds to the colour table in Oracle and then removing those rows which match the rows retrieved from the product_colour Oracle table (available in the colours Set in the preceding snippet) satisfying the condition as mentioned earlier such as,
List<Colour>colourList=session.createQuery("from Colour order by colourId desc").list();
Iterator<Colour>it=colourList.iterator();
while(it.hasNext())
{
Colour c=(Colour)it.next();
for(Colour pc:colours) //colours is available in the preceding snippet.
{
if(c==pc)
{
it.remove();
}
}
}
This can do what is intended but doing so, may imply some overhead on the system. Additionally, what I want to achieve doesn't seem possible with this approach which is pagination. I can't use the setFirstResult(int) and the setMaxResults(int) methods to accomplish the task of pagination which is the case otherwise like the one shown below regarding the Product entity class,
List<Product> products=session.createQuery("from product order by prodId desc")
.setMaxResults(0).setFirstResult(4);
So the question is again, regarding this relationship, is this possible to write such an HQL statement that can retrieve only those rows from the Colour entity class which don't match the colour rows in the product_colour Oracle table like the native SQL statement shown above?
How can I achieve the concept of pagination otherwise (in case, it is not possible)?
Short answer to a veeeeery long question:
select colour from Colour colour
where colour.id not in (
select colour2.id from Product product
inner join product.colours colour2
where product.id = :productId)
Related
I am trying to model a company and its relevant employee strucutre. I have 3 tables (company, position, employee) as below, and company haveMany position, and employee haveMany position. Position belongs to company, and position belongs to employee.
However, different position have some common field like onboard date, but have some fields are different. Forexmaple, CEO has a gurantee employment period, while other position dont. Quite a number of field is different too for different position.
In that case, should I using polymorphic to model? but as the company has quite a number of different position, this will create quite a lot new table in the database.
Do you have any advice on how to model different positions?
Companies
id
Position
Positions
id
type [CEO, manager, director, clerk, etc]
company_id
employee_id
Onboard Date
Ceased Date
Employees
id
position id
In that case, should I using polymorphic to model? but as the company has quite a number of different position, this will create quite a lot new table in the database.
No, why would be?
First of all, it should be manyToMany relation and not oneToMany because if you have two companies both of those can have CEO (for example) position and if you set $position->belongsTo(Company::class); it couldn't work.
It is polymorph relation there with positions as polymorphic angle of that triangle.
You would need
// companies
id
name
// employees
id
name
// positions
id
name
// positionables
position_id
positionable_id
positionable_type
With this, your models would be
class Company extends Model
{
public function positions()
{
return $this->morphToMany(Position::class, 'positionable');
}
}
class Employee extends Model
{
public function positions()
{
return $this->morphToMany(Position::class, 'positionable');
}
}
class Position extends Model
{
public function companies()
{
return $this->morphedByMany(Company::class, 'positionable');
}
public function employees()
{
return $this->morphedByMany(Company::class, 'positionable');
}
}
It allows you to set positions, companies and employees separately. Meaning, From dashboard you can make some new positions that will be available on frontend from select options let's say. Of course you should allow company and to employee to create new position (I suggest) and not just to use existing one but it could be out of scope of this question now: in example, when (and if) company creates new position (instead of selecting existing ones from options list), you would first create that position and store it into positions table and then associate company with it. Also, when using this kind of chained inputs to DB don't forget to use DB transactions. Into positionables table you would set other fields important for each relation (onboard_date, ceased_date, etc).
Documentation is very good and consult it if something is not clear (I hope it is already).
Disclaimer: I don't know rest of your project business plan and rest of project's requirements but for these three entities this is the best structure you can go with. I have set just mandatory members to models and tables for this example. Also in offered answer, I presumed use of Laravel's naming convention that's blindly followd from docs and this repo.
If the fields have no relationship with other tables, one possible way is to have a key-value table to store those fields and values:
position_fields
- id
- position_id
- key
- value
You can hence store the fields in key and the respective value in value. Then you may overwrite the __get magic method in Position model e.g.
public function __get($key){
$position_field = $this->hasMany(PositionField::class)->where('key', $field)->first();
return !!$position_field ? $position_field->value : $this->getAttribute($key);
}
I am creating entity for table created outside of my system. I want to bind data from other table to entity field by using #SecondaryTable (or possibly better solution), but only to do so if condition is met. IE. my table has 1 row, I want to bind data from other table (oneToMany) where certain condition is met (exactly one match from other table(transform to one to one)). Can I use #Where annotation and how? If not is there alternative?
Edit: here is the entity and additional info on the related table
#Entity
#Table(name = "RE_STORAGE_INSTANCE")
public class Movie {
#Id
#Column(name="ID_")
private Long id;
...
//Column I want to fetch
private Date dueDate;
}
Table RE_VARIABLES manyToOne to table RE_STORAGE_INSTANCE, contains fields: re_key, re_value. I want to fetch re_value only if 're_key' equals dueDate. Even though it's manyToOne, only one row of RE_VARIABLES contains due date for each RE_STORAGE_INSTANCE row.
I have too classes and two non-TYPO3-tables. I defined a non-TYPO3-table as a table without uid, pid, etc. columns.
My two classes:
class Tx_Abc_Domain_Model_Location extends Tx_Extbase_DomainObject_AbstractEntity
class Tx_Abc_Domain_Model_Facility extends Tx_Extbase_DomainObject_AbstractEntity
My two tables (with columns):
locations
zipcode
city
facility_id
facilities
facility_id
name
I've mapped the attributes like this:
config.tx_extbase.persistence.classes {
Tx_Abc_Domain_Model_Location.mapping {
tableName = locations
columns {
zipcode.mapOnProperty = zipcode
city.mapOnProperty = city
facility_id.mapOnProperty = facility
}
}
Tx_Abc_Domain_Model_Facility.mapping {
tableName = facilities
columns {
facility_id.mapOnProperty = uid
name.mapOnProperty = name
}
}
}
My problem:
The facility attribute of my location model got the type Tx_Abc_Domain_Model_Facility and when I'm looking for a location via the LocationRepository it builds me a location model which contains a facility model.
The problem appears, when I the search I am doing returns several results. i.e. the location with the zipcode 12345 has two different facilities (and the table locations got two rows with different facility_ids), then I would expect to get two location models and each of it got the right facility model.
But instead I get the two location models, which have all same facility model inside. They've got all the facility of the first found location.
Even if I change the type of the facility attribute to integer, there are the wrong ids. But if I enable raw query result in repository I get the correct ids.
I get also the correct ids or models, when I add to both tables an uid-column.
Is there no possibility to map tables without uid column with Extbase models?
Thanks.
Okay, the answer to my last question is: Yes, there is no possibility to map tables without uid column with Extbase models.
There is an existing ticket on forge: http://forge.typo3.org/issues/25984
The reason seems to be the hardcoded $row['uid'] in mapSingleRow() method in Tx_Extbase_Persistence_Mapper_DataMapper class.
If it's not alot of tables you have to map, a work-around could be to create views for those tables to just map the uid.
I.e.:
CREATE VIEW tx_abc_domain_model_facility AS
SELECT facility_id AS uid, facilities.* FROM facilities;
I have the following HQL in Hibernate using Spring MVC.
List<Colour>list=session.createQuery("from Colour order by colourId desc")
.setFirstResult((currentPage-1)*rowsPerPage)
.setMaxResults(rowsPerPage).list();
It works and returns a list of rows from the colour table (actually operates upon the Colour entity (POJO) that I can understand) in Oracle 10g.
What if I need to retrieve a list fields, I'm trying the following.
List<Colour>list=session.createQuery("colourId, colourName, colourHex from Colour order by colourId desc")
.setFirstResult((currentPage-1)*rowsPerPage)
.setMaxResults(rowsPerPage).list();
It ends with an excpetion
java.lang.IllegalArgumentException: node to traverse cannot be null!
In some articles, it was mentioned that the following version of HQL should (or may) work
List<Colour>list=session.createQuery("select colourId, colourName, colourHex from Colour order by colourId desc")
.setFirstResult((currentPage-1)*rowsPerPage)
.setMaxResults(rowsPerPage).list();
but unfortunately, it also didn't work for me. Using the createSQLQuery() method to execute native SQL would work but I want to stick to the createQuery() method with HQL unless it's absolutely necessary. How can I specify a list of fields in HQL?
I agree with yorkw's comment. If you select properties in your query then you cannot ask for a List<Colour> object to be returned from a call to .list().
Instead you should do this
List<Object[]> rows = session.createQuery("select c.colourId, c.colourName, c.colourHex " +
" from Colour c " +
" order by c.colourId desc").list();
Then iterate over the list object and instantiate your objects. Or whatever you need to do.
for ( Object[] row : rows ) {
Long colourId = (Long)row[0];
// ... etc
}
Why don't you try creating a map? Something like this:
SELECT NEW MAP( colour.colourId AS id
, colour.colourName AS name ...)
FROM Colour colour
ORDER BY colour.colourId
I use the alias for Colour "colour" so hibernate knows from which entity is the property I am referencing, I am implying all those properties are from the same entity, if not, then check your referencing!
Let's say I have an Order table which has a FirstSalesPersonId field and a SecondSalesPersonId field. Both of these are foreign keys that reference the SalesPerson table. For any given order, either one or two salespersons may be credited with the order. In other words, FirstSalesPersonId can never be NULL, but SecondSalesPersonId can be NULL.
When I drop my Order and SalesPerson tables onto the "Linq to SQL Classes" design surface, the class builder spots the two FK relationships from the Order table to the SalesPerson table, and so the generated Order class has a SalesPerson field and a SalesPerson1 field (which I can rename to SalesPerson1 and SalesPerson2 to avoid confusion).
Because I always want to have the salesperson data available whenever I process an order, I am using DataLoadOptions.LoadWith to specify that the two salesperson fields are populated when the order instance is populated, as follows:
dataLoadOptions.LoadWith<Order>(o => o.SalesPerson1);
dataLoadOptions.LoadWith<Order>(o => o.SalesPerson2);
The problem I'm having is that Linq to SQL is using something like the following SQL to load an order:
SELECT ...
FROM Order O
INNER JOIN SalesPerson SP1 ON SP1.salesPersonId = O.firstSalesPersonId
INNER JOIN SalesPerson SP2 ON SP2.salesPersonId = O.secondSalesPersonId
This would make sense if there were always two salesperson records, but because there is sometimes no second salesperson (secondSalesPersonId is NULL), the INNER JOIN causes the query to return no records in that case.
What I effectively want here is to change the second INNER JOIN into a LEFT OUTER JOIN. Is there a way to do that through the UI for the class generator? If not, how else can I achieve this?
(Note that because I'm using the generated classes almost exclusively, I'd rather not have something tacked on the side for this one case if I can avoid it).
Edit: per my comment reply, the SecondSalesPersonId field is nullable (in the DB, and in the generated classes).
The default behaviour actually is a LEFT JOIN, assuming you've set up the model correctly.
Here's a slightly anonymized example that I just tested on one of my own databases:
class Program
{
static void Main(string[] args)
{
using (TestDataContext context = new TestDataContext())
{
DataLoadOptions dlo = new DataLoadOptions();
dlo.LoadWith<Place>(p => p.Address);
context.LoadOptions = dlo;
var places = context.Places.Where(p => p.ID >= 100 && p.ID <= 200);
foreach (var place in places)
{
Console.WriteLine(p.ID, p.AddressID);
}
}
}
}
This is just a simple test that prints out a list of places and their address IDs. Here is the query text that appears in the profiler:
SELECT [t0].[ID], [t0].[Name], [t0].[AddressID], ...
FROM [dbo].[Places] AS [t0]
LEFT OUTER JOIN (
SELECT 1 AS [test], [t1].[AddressID],
[t1].[StreetLine1], [t1].[StreetLine2],
[t1].[City], [t1].[Region], [t1].[Country], [t1].[PostalCode]
FROM [dbo].[Addresses] AS [t1]
) AS [t2] ON [t2].[AddressID] = [t0].[AddressID]
WHERE ([t0].[PlaceID] >= #p0) AND ([t0].[PlaceID] <= #p1)
This isn't exactly a very pretty query (your guess is as good as mine as to what that 1 as [test] is all about), but it's definitively a LEFT JOIN and doesn't exhibit the problem you seem to be having. And this is just using the generated classes, I haven't made any changes.
Note that I also tested this on a dual relationship (i.e. a single Place having two Address references, one nullable, one not), and I get the exact same results. The first (non-nullable) gets turned into an INNER JOIN, and the second gets turned into a LEFT JOIN.
It has to be something in your model, like changing the nullability of the second reference. I know you say it's configured as nullable, but maybe you need to double-check? If it's definitely nullable then I suggest you post your full schema and DBML so somebody can try to reproduce the behaviour that you're seeing.
If you make the secondSalesPersonId field in the database table nullable, LINQ-to-SQL should properly construct the Association object so that the resulting SQL statement will do the LEFT OUTER JOIN.
UPDATE:
Since the field is nullable, your problem may be in explicitly declaring dataLoadOptions.LoadWith<>(). I'm running a similar situation in my current project where I have an Order, but the order goes through multiple stages. Each stage corresponds to a separate table with data related to that stage. I simply retrieve the Order, and the appropriate data follows along, if it exists. I don't use the dataLoadOptions at all, and it does what I need it to do. For example, if the Order has a purchase order record, but no invoice record, Order.PurchaseOrder will contain the purchase order data and Order.Invoice will be null. My query looks something like this:
DC.Orders.Where(a => a.Order_ID == id).SingleOrDefault();
I try not to micromanage LINQ-to-SQL...it does 95% of what I need straight out of the box.
UPDATE 2:
I found this post that discusses the use of DefaultIfEmpty() in order to populated child entities with null if they don't exist. I tried it out with LINQPad on my database and converted that example to lambda syntax (since that's what I use):
ParentTable.GroupJoin
(
ChildTable,
p => p.ParentTable_ID,
c => c.ChildTable_ID,
(p, aggregate) => new { p = p, aggregate = aggregate }
)
.SelectMany (a => a.aggregate.DefaultIfEmpty (),
(a, c) => new
{
ParentTableEntity = a.p,
ChildTableEntity = c
}
)
From what I can figure out from this statement, the GroupJoin expression relates the parent and child tables, while the SelectMany expression aggregates the related child records. The key appears to be the use of the DefaultIfEmpty, which forces the inclusion of the parent entity record even if there are no related child records. (Thanks for compelling me to dig into this further...I think I may have found some useful stuff to help with a pretty huge report I've got on my pipeline...)
UPDATE 3:
If the goal is to keep it simple, then it looks like you're going to have to reference those salesperson fields directly in your Select() expression. The reason you're having to use LoadWith<>() in the first place is because the tables are not being referenced anywhere in your query statement, so the LINQ engine won't automatically pull that information in.
As an example, given this structure:
MailingList ListCompany
=========== ===========
List_ID (PK) ListCompany_ID (PK)
ListCompany_ID (FK) FullName (string)
I want to get the name of the company associated with a particular mailing list:
MailingLists.Where(a => a.List_ID == 2).Select(a => a.ListCompany.FullName)
If that association has NOT been made, meaning that the ListCompany_ID field in the MailingList table for that record is equal to null, this is the resulting SQL generated by the LINQ engine:
SELECT [t1].[FullName]
FROM [MailingLists] AS [t0]
LEFT OUTER JOIN [ListCompanies] AS [t1] ON [t1].[ListCompany_ID] = [t0].[ListCompany_ID]
WHERE [t0].[List_ID] = #p0