Short Description
How do I make findBy<Field>In work with IN when the array list input is null. e.g. ignore it. What would your DAO for this look like?
Longer description.
Imagine you have creating a search for users page.
in the application. You have various options to filter on.
created (date range always given)
Country (when null ignore and search all countries)
AgeRange
Job Title
etc...
Now say you want to search for all users in a given date range in a list of countries.
When searching for users I will always search for a date joined however if I have not selected a country I want it to search for all countries.
I am planning on adding several more filter options other than country. So I don't really want to create lots of findBy methods for each possible field combination.
DAO
#Repository
public interface UserDao extends JpaRepository<User, Long> {
public List<BeatRate> findByCreatedBetweenAndCountryIn(Date from, Date to, ArrayList<String> countryList );
}
Test
#Test
public void test() throws ParseException {
Date from = new SimpleDateFormat( "yyyy-MM-dd" ).parse( "2015-01-01" );
Date to = new SimpleDateFormat("yyyy-MM-dd").parse("2015-05-15");
//ArrayList<String> countryList = new ArrayList<String>();
//countryList.add("UK");
//countryList.add("Australia");
//countryList.add("Japan"); // works ok when I have a list
countryList = null; // I want it to search for all countries when this is null -- this errors and doesnt work..
List<BeatRate> beatRates = beatRateDao.findByCreatedBetweenAndRentalCountryIn(from, to, countryList);
Assert.assertTrue(beatRates.size()>0);
}
You can have two methods:
beatRateDao.findByCreatedBetweenAndRentalCountryIn(from, to, countryList);
and
beatRateDao.findByCreatedBetweenAndRental(from, to);
Then simply pick one based on countryList:
List<BeatRate> beatRates = (countryList != null && !countryList.isEmpty())
? beatRateDao.findByCreatedBetweenAndRentalCountryIn(from, to, countryList)
: beatRateDao.findByCreatedBetweenAndRental(from, to);
The IN clause requires a non-nullable and non empty argument list as otherwise the query will fail.
On PostgreSQL, if you try to run a query like this:
select *
from product
where quantity in ( )
you get the following error:
ERROR: syntax error at or near ")"
LINE 3: where quantity in ( )
^
********** Error **********
ERROR: syntax error at or near ")"
SQL state: 42601
Character: 45
Related
I have an entity for driving_info with lot of fields but one of them is a phone number ( from which was ordered ).
What I am trying to do is to fetch all drives that were ordered from that number. But when I try to pass the int of phoneNumber I get
query did not return a unique result: 5; nested exception is javax.persistence.NonUniqueResultException: query did not return a unique result: 5
org.springframework.dao.IncorrectResultSizeDataAccessException: query did not return a unique result: 5; nested exception is javax.persistence.NonUniqueResultException: query did not return a unique result: 5
I actually want the list of results so that I can get a response of list of all drives that were ordered from that phone number.
My controller method is
#GetMapping("/users/{phone}")
public List<User> getUserByPhone(#PathVariable int phone) {
List<User> users= userService.findByPhone(phone);
if(users == null) {
throw new RuntimeException("User not found with "+phone+" phone number");
}
return users;
}
And my DAO is
#Override
#Transactional
public List<User> findByPhone(int phone) {
Session currentSession = entityManager.unwrap(Session.class);
Query<User> theQuery = currentSession.createQuery("from User where phone=:phone",User.class);
List<User> users = theQuery.getResultList();
return users;
}
Try to correct your query in this way:
List<User> users = currentSession.createQuery(
"select u from User u where u.phone = :phone",
User.class
).setParameter( "phone", phone )
.getResultList();
Please note that as it's stated in the documentation:
Even though HQL does not require the presence of a select_clause, it is generally good practice to include one. For simple queries the intent is clear and so the intended result of the select_clause is easy to infer. But on more complex queries that is not always the case.
It is usually better to explicitly specify intent. Hibernate does not actually enforce that a select_clause be present even when parsing JPQL queries, however, applications interested in JPA portability should take heed of this.
You need to call theQuery.list() instead.
I am implementing server-side filtering of dataTable. In the service which implements the filtering I want to test if the search criteria is a number ; if so then I implement the filtering based on the bean attribute of type double ( salary ) , otherwise I make the filtering based on the bean attribute of type String ( username ) :
#Override
#Transactional
public List<User> list(int start, int length, String search) {
Criteria criteres = sessionFactory.getCurrentSession().createCriteria(User.class);
if (!search.equals("")) {
if (NumberUtils.isNumber(search))
criteres.add(Restrictions.like("salary", Double.parseDouble(search)));
else
criteres.add(Restrictions.like("username", search, MatchMode.ANYWHERE));
}
criteres.setFirstResult(start);
criteres.setMaxResults(length);
criteres.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);
#SuppressWarnings("unchecked")
List<User> listUser = (List<User>) criteres.list();
return listUser;
}
The problem is that if I write :
if (!search.equals("")) {
if (NumberUtils.isNumber(search))
criteres.add(Restrictions.like("salary", String.valueOf(Double.parseDouble(search)), MatchMode.ANYWHERE));
else
criteres.add(Restrictions.like("username", search, MatchMode.ANYWHERE));
}
then I got alert error : DataTables warning: table id=t_list - Ajax error. For more information about this error, please see http://datatables.net/tn/7
So how to make possible to make a "like" condition on the double variable ?
I'm developing a Spring web application whose persistence layer consists in Spring Roo generated JPA entities, with Hibernate as persistence provider and MySql as underlying DB.
Among my entities I have a class Detection with a tstamp java.util.Date field generated in Roo as follows:
entity jpa --class ~.data.Detection
...
field date --fieldName tstamp --type java.util.Date
...
finder add findDetectionsByTstampBetween
(the finder method was of course chosen after executing finder list)
In my controller code, at a point I invoke:
List<Detection> detections = Detection.findDetectionsByTstampBetween(from, to).getResultList();
Where from and to are two valid java.util.Date(s). When testing sample data though (after ensuring that for a given choice of from, to the returned list shouldn't be empty), I got an empty list and investigated the reasons.
I found in tomcat logs that Hibernate was generating the following SQL:
Hibernate: select detection0_.id as id1_3_, ...etc..., detection0_.tstamp as tstamp4_3_ from detection detection0_ where detection0_.tstamp>=?
I would expect the where clause should contain a trailing "AND detection0_.tstamp<=?", checking the other date range limit. I took a look at the generated Detection.findDetectionsByTstampBetween(Date minTstamp, Date maxTstamp) method in Detection_Roo_Finder.aj and actually the "AND" is present in the invocation to createQuery.
public static TypedQuery<Detection> Detection.findDetectionsByTstampBetween(Date minTstamp, Date maxTstamp) {
if (minTstamp == null) throw new IllegalArgumentException("The minTstamp argument is required");
if (maxTstamp == null) throw new IllegalArgumentException("The maxTstamp argument is required");
EntityManager em = Detection.entityManager();
TypedQuery<Detection> q = em.createQuery("SELECT o FROM Detection AS o WHERE o.tstamp BETWEEN :minTstamp AND :maxTstamp", Detection.class);
q.setParameter("minTstamp", minTstamp);
q.setParameter("maxTstamp", maxTstamp);
return q;
}
Any idea what could cause the problem?
I've finally found the solution to the riddle and, as it turned out, the issue had nothing to do with JPA.
The problem was that the call to the persistence layer was inserted inside a Rest service controller with the following mapping:
#ResponseBody
#RequestMapping(value="/detections", method=RequestMethod.GET, params="from, to" )
public Object getDetectionsInRange(
#RequestParam(required=true) #DateTimeFormat(pattern="yyyy-MM-dd HH:mm") final Date from,
#RequestParam(required=true) #DateTimeFormat(pattern="yyyy-MM-dd HH:mm") final Date to
)
{
...
List<Detection> detections = Detection.findDetectionsByTstampBetween(from, to).getResultList();
...
}
The error was in the definition of the params= argument in #RequestMapping, the correct format being as follows:
#RequestMapping(value="/detections", method=RequestMethod.GET, params={"from", "to"} )
This error caused another version of the controller method for /detections. In this second version I called a different finder method, which appeared to generate the wrong SQL in Hibernate.
#ResponseBody
#RequestMapping(value="/detections", method=RequestMethod.GET )
public Object getDetections(
#RequestParam(required=false, defaultValue="0") int days,
#RequestParam(required=false, defaultValue="0") int hours,
#RequestParam(required=false, defaultValue="0") int minutes
)
{
...
List<Detection> detections = Detection.findDetectionsByTstampGreaterThanEquals( ... ).getResultList();
...
}
I typically do mobile app development, which doesn't always have .Select. However, I've seen this used a bit, but I don't really know what it does or how it's doing whatever it does. It is anything like
from a in list select a // a.Property // new Thing { a.Property}
I'm asking because when I've seen code using .Select(), I was a bit confused by what it was doing.
.Select() is from method syntax for LINQ, select in your code from a in list select a is for query syntax. Both are same, query syntax compiles into method syntax.
You may see: Query Syntax and Method Syntax in LINQ (C#)
Projection:
Projection Operations - MSDN
Projection refers to the operation of transforming an object into a
new form that often consists only of those properties that will be
subsequently used. By using projection, you can construct a new type
that is built from each object. You can project a property and perform
a mathematical function on it. You can also project the original
object without changing it.
You may also see:
LINQ Projection
The process of transforming the results of a query is called
projection. You can project the results of a query after any filters
have been applied to change the type of the collection that is
returned.
Example from MSDN
List<string> words = new List<string>() { "an", "apple", "a", "day" };
var query = from word in words
select word.Substring(0, 1);
In the above example only first character from each string instance is selected / projected.
You can also select some fields from your collection and create an anonymous type or an instance of existing class, that process is called projection.
from a in list select new { ID = a.Id}
In the above code field Id is projected into an anonymous type ignoring other fields. Consider that your list has an object of type MyClass defined like:
class MyClass
{
public int Id { get; set; }
public string Name { get; set; }
public string Address { get; set; }
}
Now you can project the Id and Name to an anonymous type like:
Query Syntax:
var result = from a in list
select new
{
ID = a.Id,
Name = a.Name,
};
Method Syntax
var result = list.Select(r => new { ID = r.Id, Name = r.Name });
You can also project result to a new class. Consider you have a class like:
class TemporaryHolderClass
{
public int Id { get; set; }
public string Name { get; set; }
}
Then you can do:
Query Syntax:
var result = from a in list
select new TemporaryHolderClass
{
Id = a.Id,
Name = a.Name,
};
Method Syntax:
var result = list.Select(r => new TemporaryHolderClass
{
Id = r.Id,
Name = r.Name
});
You can also project to the same class, provided you are not trying to project to classes generated/created for LINQ to SQL or Entity Framework.
My summary is it takes results (or a subset of results) and allows you to quickly restructure it for use in the local context.
The select clause produces the results of the query and specifies the
"shape" or type of each returned element. For example, you can specify
whether your results will consist of complete Customer objects, just
one member, a subset of members, or some completely different result
type based on a computation or new object creation.
Source: http://msdn.microsoft.com/en-us/library/bb397927.aspx
There are a lot of possible uses for this but one is taking a complex object which of many other contains a property that is a string -- say Name -- and allows you to return an enumeration with just the entries of Name. I believe you can also do the opposite -- use that property ( for example) and create / return new type of object while passing in a property or properties.
It means "mapping". Map each element of a sequence to a transformed sequence. I hadn't comprehended its meaning before I looked at the image.
Where does the meaning of the word come from?
Simply, math! https://mathworld.wolfram.com/Projection.html
I'm getting a strange error when running what appears to be a simple query.
return (from x in session.Query<Contact>()
.Where(x => x.Id == 10)
select new ContactIndexViewModel
{
Id = x.Id,
Name = x.BasicInfo.FirstName + " " + x.BasicInfo.LastName,
Filters = x.Filters
}).FirstOrDefault();
Is generating the following SQL
select
contact0_.[Id] as col_0_0_,
contact0_.[BasicInfoFirstName] as col_1_0_,
contact0_.[BasicInfoLastName] as col_2_0_,
. as col_3_0_,
filters1_.[Id] as column1_16_,
filters1_.Criteria1 as Criteria2_16_,
// .. .more filters1_ fields
filters1_.ContactId as ContactId16_
from
[MyServer].[dbo].[Contact] contact0_
inner join [MyServer].[dbo].[Filter] filters1_
on contact0_.[Id]=filters1_.ContactId
where
contact0_.[Id]=#p0
Notice the fourth column being selected. BasicInfo is a component and the select (in the query) includes all the fields defined in the ViewModel.
I am not having any other problems with the Contact or Filter objects in other parts of the application. Contact -> Filter has a one to many relationship.
Any idea's on how to debug or what may cause this?
UPDATE
If I remove the reference to Filters in the select, the problem goes away.
UPDATE Relevant Mappings
Contact
public partial class ContactMap : ClassMap<Contact>
{
/// <summary>Initializes a new instance of the <see cref="ContactMap"/> class.</summary>
public ContactMap()
{
Table("[MyServer].[dbo].[Contact]");
OptimisticLock.Version();
DynamicUpdate();
LazyLoad();
Id(x=>x.Id)
.Access.CamelCaseField(Prefix.Underscore)
.Column("[Id]")
.GeneratedBy.Identity();
Version(x=>x.RecordVersion)
.Access.CamelCaseField(Prefix.Underscore)
.Column("[RecordVersion]")
.CustomSqlType("timestamp")
.Not.Nullable()
.UnsavedValue("null")
.CustomType("BinaryBlob")
.Generated.Always();
Map(x=>x.Active).Access.CamelCaseField(Prefix.Underscore);
// other scalar properties
Component(x0=>x0.BasicInfo, m0=>
{
m0.Map(x1=>x1.FirstName).Column("[BasicInfoFirstName]").Access.CamelCaseField(Prefix.Underscore);
m0.Map(x1=>x1.LastName).Column("[BasicInfoLastName]").Access.CamelCaseField(Prefix.Underscore);
// other scalar properties
});
// other relationships
HasMany(x=>x.Searches)
.Access.CamelCaseField(Prefix.Underscore)
.Cascade.AllDeleteOrphan()
.Fetch.Select()
.Inverse()
.LazyLoad()
.KeyColumns.Add("ContactId");
}
}
Search
public partial class SearchMap : ClassMap<Search>
{
public SearchMap()
{
Table("[MyServer].[dbo].[Search]");
OptimisticLock.Version();
DynamicUpdate();
LazyLoad();
Id(x=>x.Id)
.Access.CamelCaseField(Prefix.Underscore)
.Column("[Id]")
.GeneratedBy.Identity();
Map(x=>x.Controller).Not.Nullable().Access.CamelCaseField(Prefix.Underscore);
Map(x=>x.Module).Not.Nullable().Access.CamelCaseField(Prefix.Underscore);
Map(x=>x.Name).Column("[Name]").Not.Nullable().Access.CamelCaseField(Prefix.Underscore);
References(x=>x.Contact)
.Access.CamelCaseField(Prefix.Underscore)
.Cascade.All()
.Fetch.Select()
.Columns("ContactId");
HasMany(x=>x.DataFilters)
.Access.CamelCaseField(Prefix.Underscore)
.Cascade.AllDeleteOrphan()
.Fetch.Select()
.Inverse()
.LazyLoad()
.KeyColumns.Add("SearchId");
}
}
Did you map Filters with FetchMode.Join?
By the way, it may be easier to create the ContactIndexViewModel in memory, with the trade off that it fetches too many columns from the database. On the other side, Get doesn't flush the session, which may be performance relevant.
var contact = session.Get<Contact>(10);
return new ContactIndexViewModel
{
Id = contact.Id,
Name = contact.BasicInfo.FirstName + " " + contact.BasicInfo.LastName,
Filters = contact.Filters
};
Your mapping for the table is unusual to me.
Table("[MyServer].[dbo].[Contact]");
Normally the server name is provided during configuration, the schema is stated separately, and the delimiters ("[...]") are set by NHibernate. I would map it as:
Schema("dbo");
Table("Contact");
That may be causing a parsing problem leading to the odd select. If that's not it, then I think it's a bug -- NHibernate should never issue a select without a table alias and column name.