I have a class with the following fields:
class Offer {
#QuerySqlField
private Flight departure;
#QuerySqlField
private Flight return;
}
Both fields are Flight, specified below:
class Flight {
#QuerySqlField(name = "flightCode")
private String flightCode;
}
When looking at the database I see only one flightCode given that Apache Ignite flattened it. Is there a way to map departureFlightCode and returnFlightCode without creating an extra class?
Using nested classes is not recommended because there are gaps in their support.
You can use QueryEntities for mapping of object to table, and Binarylizable to specify how your object maps to cache entry.
Related
I'm trying to use RepoDb to query the contents of a table (in an existing Sql Server database), but all my attempts result in an InvalidOperationException (There are no 'contructor parameter' and/or 'property member' bindings found between the resultset of the data reader and the type 'MyType').
The query I'm using looks like the following:
public Task<ICollection<MyType>> GetAllAsync()
{
var result = new List<MyType>();
using (var db = new SqlConnection(connectionString).EnsureOpen())
{
result = (await db.ExecuteQueryAsync<MyType>("select * from mytype")).ToList();
}
return result;
}
I'm trying to run this via a unit test, similar to the following:
[Test]
public async Task MyTypeFetcher_returns_all()
{
SqlServerBootstrap.Initialize();
var sut = new MyTypeFetcher("connection string");
var actual = await sut.GetAllAsync();
Assert.IsNotNull(actual);
}
The Entity I'm trying to map to matches the database table (i.e. class name and table name are the same, property names and table column names also match).
I've also tried:
putting annotations on the class I am trying to map to (both at the class level and the property level)
using the ClassMapper to map the class to the db table
using the FluentMapper to map the entire class (i.e. entity-table, all columns, identity, primary)
putting all mappings into a static class which holds all mapping and configuration and calling that in the test
providing mapping information directly in the test via both ClassMapper and FluentMapper
From the error message it seems like RepoDb cannot find the mappings I'm providing. Unfortunately I have no idea how to go about fixing this. I've been through the documentation and the sample tutorials, but I haven't been able to find anything of use. Most of them don't seem to need any mapping configuration (similar to what you would expect when using Dapper). What am I missing, and how can I fix this?
I have a question about a standard pattern or mechanism in spring-hateoas or Spring Rest Data about encrypting the IDs of the Resources/Entities.
The reason I am asking, a requirement to our project is that we don't deliver the id's of our objects to the outside world and they should not be used in GET Requests as Parameters.
I know, Spring Rest Data and spring-hateoas does not give the ids of the objects unless they are configured so but even that case I can see the ids in links.
I know I can use PropertyEditors or Converters to encrypt/decrypt ids before and after Json serialisation/deseritalisation but I just like to know is there a more standard way?
Thx for answers...
If you have the unique 'business id' property of your resource you can configure SDR to use it instead of the entity ID.
First you have to create lookup method of your entity with this unique property:
public interface MyEntityRepo extends JpaRepository<MyEntity, Long> {
#RestResource(exported = false)
Optional<CatalogResource> findByMyUniqueProperty(String myUniqueProperty);
}
Then use it to configure SDR:
#Component
public class DataRestConfig extends RepositoryRestConfigurerAdapter {
#Override
public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {
config.withCustomEntityLookup()
.forRepository(MyEntityRepo.class, MyEntity::getMyUniqueProperty, MyEntityRepo::findByMyUniqueProperty);
super.configureRepositoryRestConfiguration(config);
}
}
After this customization you will have resource URI like this:
http://localhost:8080/myEntities/myUniquePropertyValue1
By default, in Spring Data Rest the #Id of the entity is not exposed. In line with the REST rules, we're supposed to use the URI of the resource to refer to it. Given this assumption, the findBy queries should work if you pass a URI to them, but they don't.
For example, say I have a one-to-many relationship between Teacher and Student. I want to find students by teacher.
List<Student> findByTeacher(Teacher teacher)
http://localhost:8080/repositories/students/search/findByTeacher?teacher=http://localhost:8080/repositories/teachers/1
This doesn't work because the framework is attempting to convert the teacher URI to a Long.
I get this error that says "Failed to convert from type java.lang.String to type java.lang.Long".
Am I missing something?
You could expose #Id s by configuring web intializer
//Web intializer
#Configuration
public static class RespositoryConfig extends
RepositoryRestMvcConfiguration {
#Override
protected void configureRepositoryRestConfiguration(
RepositoryRestConfiguration config) {
config.exposeIdsFor(Teacher.class);
}
}
Its good to change List to Page
List findByTeacher(Teacher teacher)
to
Page<Student> findByTeacher(#Param("teacher) Teacher teacher, Pageable pageable);
Also note #Param annotation is required along with Pageable. The latter is required because return type "Page"
3.Latest snapshots, not milestones work fine
See https://jira.spring.io/browse/DATAREST-502
Depending of your version of Spring Data, it would work as you want or not. If you are with Spring Data 2.4, you need to pass the URI. If you are with a previous version, you need to pass the id.
I am looking for some way to dynamically map database tables classes in my application using nhibernate (or if some other ORM works then let me know). I am fairly new to nhibernate, I used entity frameworks in the past though.
Most of my application will be using a static structures and fluent nhibernate to map them.
However there are multiple database tables that will be needed to be created and mapped to objects at each install site. These will all have as a base structure (id,name etc) however they will have additional fields depending on the type of data they are capturing. From some reading I found that I can use the "dynamic-component" mapping in xml to add fields using an IDictionary Attributes property. This is the first step and seems relatively straight forward. Ref (http://ayende.com/blog/3942/nhibernate-mapping-dynamic-component)
The second step is where I am struggling. I will need to define tables and map them depending on the client’s need. As stated above each of the tables will have a set of static properties, and some dynamic ones. They will also need to reference a static “Location”Class as shown below
Location (STATIC) (id,coordinates)
-----DynamicTable1 (DYNAMIC) (id,Name,location_id, DynamicAttribute1, DynamicAttribute2........)
-----DynamicTable2 (DYNAMIC) (id,Name,location_id, DynamicAttributeA, DynamicAttributeB....)
We will need to be able to create / map as many of these DynamicTables as the client needs. DynamicTable1, DynamicTable2 etc will most likely be different in some ways for most client sites. Is there any way in nhibernate to achieve this? The creating / management of the tables in the Database will be managed elsewhere, I just need some way to get this to map in my ORM.
A bit of background
This application will be used to store geological data. As geological data is inherently different depending on where it is, and geologist are using different methods and looking for different elements (gold, coal etc), the data structure to store this information needs to be extremely flexible.
Take a look at the new Mapping By Code functionality of NH 3.2. It should make it easy to create new table definitions at runtime. In contrast to Fluent, you don't need to write a mapping class, you just can add new classes in for loops:
// lookup all dynamic tables in the database using SQL or SMO or whatever
var dynamicTables = GetDynamicTables();
// map all dynamic tables
foreach(var table in dynamicTables)
{
mapper.Class<MyGenericEntity>(ca =>
{
// use an entity name to distinguish the mappings.
ca.EntityName(table.Name);
ca.Id(x => x.Id, map =>
{
map.Column("Id");
map.Generator(Generators.HighLow, gmap => gmap.Params(new { max_low = 100 }));
});
// map properties, using what ever is required: if's, for's ...
ca.Property(x => x.Something, map => map.Length(150));
});
}
Using the entity name you can store and load the entities to and from different tables, even if they are mapped as the same entity class. It is like Duck Typing With NHibernate..
Believe me, it won't be easy. If you are interested in a big challenge which impresses every NH expert, just go for it. If you just want to get it working you should choose a more classic way: create a static database model which is able to store dynamic data in a generic way (say: name value pairs).
see answer in Using nNHibernate with Emitted Code
class DynamicClass
{
public virtual int Id { get; set; }
public virtual string Name { get; set; }
public virtual Location Location { get; set; }
public virtual IDictionary DynamicData { get; set; }
}
Template
<hibernate-mapping>
<class name="DynamicClass">
...
<dynamic-component name="DynamicData">
<!--placeholder -->
</dynamic-component>
</class>
</hibernate-mapping>
replace <!--placeholder --> with generated
<property
name="P1"
type="int" />
<property
name="P2"
type="string" />
configure Sessionfactory
var sessionFactory = new NHibernate.Cfg.Configuration()
.AddXml(generatedXml)
... // DatabaseIntegration and other mappings
.BuildSessionFactory();
Query
var query = session.CreateCriteria<DynamicClass>();
foreach (var restriction in restrictions)
{
query.Add(Restrictions.Eq(restriction.Name, restriction.Value))
}
var objects = query.List<DynamicClass>();
Edit: ups i havent realised you need multiple tables per client
Option 1:
<class name="DynamicClass" table="tablenameplaceholder"> with replace and a different Sessionfactory for each dynamic class
Option 2:
Subclassing the dynamic class and use TPS (table per subclass) mappings
Option 3: see Stefans answer just with xml
<class name="DynamicTable1" class="DynamicClass" table="DynamicTable1">
I have the following model which I have created and mapped with nHibernate.
Using lazy loading so I don't need to get the Vehicles for the Dealer at the start.
Public class Dealer
{
public virtual string Name { get;set;}
public virtual IList<Vehicles> Vehicles { get;set;}
}
Now let's assume the Dealer has thousands of vehicles.
If I do Dealer.Vehicles.Count then NH will select and pull all the data.
What is the best way to simply get a count? Is there any way in which I can get a count with out declaring A new property dealerCount within the Dealer Class?
Also there is a feature in Hibernate which I believe will be implemented in a newer version of NH called Extra Lazy Loading. Would this solve the problem?
extra lazy loading would issue sql instead of populating the collection for certain operations such as Count or Contains. In fluent mappings its used as:
HasMany(x => x.CollectionProperty).ExtraLazyLoad();
or HBM
<one-to-many lazy="extra" ...
It's only usefull if you have large collections and need the special behavior.
Use count projection (Projections.RowCount)