I have two very similar methods in Grails, something like "calculate statistics by os" and "calculate statistics by browser" - effectively both prepare some things, then run a similar query on the DB, then do things with the results. The only part where the methods differ is the query they run in the middle of my method -
def summary = c.list {
eq('browser', Browser.get(1)) // OR eq('os', OS.get(1))
between('date', dates.start, dates.end)
}
It occurred to me that the ideal way to refactor it would be to pass in the first line of the closure as a method parameter. Like
doStats (Closure query) {
...
def summary = c.list {
query
between('date', dates.start, dates.end)
}
}
I tried this but "query" gets ignored. I tried query() instead but then the query clause is executed where defined, so this doesn't work either. I suppose I could just pass the whole closure as a parameter but that seems wrong - the query might also get more complicated in future.
Anyone have any better ideas?
I found leftShift operator useful for composing closure from two separate ones. What you can do is:
Closure a = { /*...*/ }
Closure b = { /*...*/ }
Closure c = a << b
Take a look at this example:
def criteria = {
projection Projections.distinct(Projections.property('id'))
and {
eq 'owner.id', userDetails.id
if (filter.groupId) {
eq 'group.id', filter.groupId
}
}
}
List<Long> ids = Contact.createCriteria().list(criteria << {
maxResults filter.max
firstResult filter.offset
})
Integer totalCount = Contact.createCriteria().count(criteria)
What you can see here is that I'm creating a criteria for listing ant counting GORM objects. Criterias for both cases are almost the same, but for listing purposes I also need to include limit and offset from command object.
You're using the criteria DSL which might be different than plain groovy closures.
To do what you're asking, you can use the method described here -
http://mrhaki.blogspot.com/2010/06/grails-goodness-refactoring-criteria.html
and put your query in to private method.
The more elegant solution for this is to use named queries in grails -
http://grails.org/doc/latest/ref/Domain%20Classes/namedQueries.html
Look at the
recentPublicationsWithBookInTitle {
// calls to other named queries…
recentPublications()
publicationsWithBookInTitle()
}
example -
Not sure about with the Grails Criteria builder, but with other builders, you can do something like:
doStats (Closure query) {
def summary = c.list {
query( it )
between('date', dates.start, dates.end)
}
}
And call this via:
def f = { criteria ->
criteria.eq( 'browser', Browser.get( 1 ) )
}
doStats( f )
If not, you're probably best looking at named queries like tomas says
Related
I noticed some behaviour I don't quite understand. It's possible to chain where queries as long as the preceding where query wasn't returned from a function.
def w = Subscription.where { topicId == 1 }
w.where { user.id == 1 }.findAll()
//works as expected
def f() {
Subscription.where { topicId == 1 }
}
f().where { user.id == 1 }.findAll()
//doesn't filter by user.id
def f() {
Subscription.where { topicId == 1 }
}
f().build { eq 'user.id', 1L }
//works
I don't mind using DetachedCriteria#build(). I'd just like to understand :-D
--- Edit
Grails 2.4.2
Grails contains a global AST transformation...
that transforms where methods into detached criteria queries.
It essentially looks for uses of where() and changes the code so that it uses detached criterias. Most likely, calling where() as you are, on the return of a method, particularly a method which returns Object, is not being acknowledged up by the AST, so the query basically ends up being unchanged and doing nothing.
It's nothing that Groovy is doing, but rather something Grails-specific. I do not claim a full, nor anything near full, understanding of what's happening, but you can get the gist of it by looking at the DetachedCriteriaTransformer source code.
I have a domain class
class Url {
UUID id
String url
static hasMany = [
indications:UrlIndication
]
...
}
And
class UrlIndication {
UUID id
String name
static belongsTo = Url
...
}
I want to choose urls so that it has all the necessary UrlIndication elements in a given list indicationsId.
For that I use an association and criteria like this one:
indications {
and {
indicationsId.each{
indication->
eq ('id',UUID.fromString(indication as String))
}
}
}
However, all I got is an empty result. Can you suggest any modifications/ other methods so that I can do this? Thanks in advance
Your query returned an empty list because it's the equivalent of the expression (pseudo-code): if 1 = 1 and 1 = 2 and 1 = 3
Such an expression would always be false. in or inList would not work for the reason #innovatism described.
In theory, Criteria's eqAll() or HQL's = ALL would work. But, I don't know for sure because I could not get either one to work.
What will work is to use inList to return a subset of Urls: those which contain at least one of the UrlIndication IDs. Then use Groovy's containsAll() to finish the job.
def ids = indicationsId.collect { UUID.fromString(it as String) }
Url.createCriteria()
.buildCriteria {
indications {
inList 'id', ids
}
}
.setResultTransformer(org.hibernate.Criteria.DISTINCT_ROOT_ENTITY)
.list()
.findAll {
it.indications.id.containsAll(ids)
}
Since the query has the potential to return duplicate Url instances, the ResultTransformer is set to return a unique list.
Finally, findAll() is used along with containsAll() to filter the list further.
Using eqAll (maybe)
Something like the following might work. Something funky is going on with Grails' HibernateCriteriaBuilder that causes the eqAll method to look up properties in the root entity; completely ignoring the sub criteria. So the following uses Hibernate directly. It didn't work for me, but it's as close as I could get. And it gave me a head-ache!
Url.createCriteria().buildCriteria {}
.createCriteria('indications', 'i')
.add(org.hibernate.criterion.Property.forName('i.id').eqAll(org.hibernate.criterion.DetachedCriteria.forClass(UrlIndication)
.add(org.hibernate.criterion.Restrictions.in('id', ids))
.setProjection(org.hibernate.criterion.Property.forName('id'))
))
.setResultTransformer(org.hibernate.Criteria.DISTINCT_ROOT_ENTITY)
.list()
The problem I had is I could not get Restrictions.in to work. Restrictions.eq works fine.
the in clause should do:
indications {
'in' 'id', indicationsId.collect{ UUID.fromString indication.toString() }
}
I am trying to find the proper syntax for a query that I know has got to be very common but couldn't find a code example for.
class ObjA {
...
static hasMany = [b:ObjB]
}
if a is an instance of ObjA, I want to perform a query like:
a.b.findAllBsSuchThat(b.someproperty = somevalue)
In order to avoid (N+1) queries for lazy associations per a, you can use a criteria as:
ObjA.withCriteria {
b {
eq 'someProperty', someValue
}
}
or where queries:
ObjA.where { b.someProperty == somevalue }.list()
If you use something like a.b.findAllBsSuchThat(b.someproperty = somevalue) then you would be getting all b's for a and then filtering on the result. This will affect the performance and will unnecessary.
What is their difference and why and where we need to use them,i think it seems like they have no difference at all to me ?
withCriteria { ... } is essentially shorthand for createCriteria().list { ... }. If you need to use any of the other criteria methods (get, count, ...) or pass pagination parameters to list then you have to use the long-hand form.
SomeDomain.createCriteria().list(max:10, offset:50) {
// ...
}
It's worth adding what I just came across in the grails documentation for createCriteria().
Because that query includes pagination parameters (max and offset), this will return a PagedResultList which has a getTotalCount() method to return the total number of matching records for pagination. Two queries are still run, but they are run for you and the results and total count are combined in the PagedResultList.
Source
This means you can use getTotalCount() without having to initiate the call (it's made for you). This is very helpful. The example documentation shows:
def c = Account.createCriteria()
def results = c.list (max: 10, offset: 10) {
like("holderFirstName", "Fred%")
and {
between("balance", 500, 1000)
eq("branch", "London")
}
order("holderLastName", "desc")
}
println "Rendering ${results.size()} Accounts of ${results.totalCount}"
This capability is not available when using withCriteria().
Example of createCriteria():
def criteria = OfferCredit.createCriteria {
offer {
eq('status', LeverageUtils.ACTIVE_STATUS)
ge('expirationDate', new Date())
}
user {
eq('userId', userId)
}
eq('status', LeverageUtils.ACTIVE_STATUS)
order('creationDate', 'asc')
}
criteria.list()
Example of withCriteria():
List<Supermarket> results = Supermarket.withCriteria {
like("sp_street", params.street)
productSupermarket {
product {
idEq(params.product)
}
// or just eq('product', someProduct)
}
maxResults(10)
}
withCriteria executes and returns the list. It provides a closure using which you can customize the criteria before it gets executed.
createCriteria just creates a criteria object which you can modify and then explicitly call the list method to execute.
If criteria is simple or if it is defined in a single place it is better to use withCriteria.
If you need to pass the criteria around (create it in one function and pass it to others) createCriteria would be better. I think withCriteria support is limited.
withCriteria ->
Purpose -> Allows inline execution of Criteria queries.
If no matching records are found, an empty List is returned.
If a projection is specified:
returns a single value if it only contains one field
a List in case there are multiple fields in the projection
Is this possible to convert in createCriteria()?
SELECT * FROM node WHERE (node.type = 'act' AND nid NOT IN (SELECT nid FROM snbr_act_community)) LIMIT 10
I know there's a 'in' operator and here's what I have so far:
def c = VolunteerOpportunity.createCriteria()
def matchingActs = c.list {
node {
eq('type', 'act')
}
maxResults(10)
}
Just want to see if this is possible. Otherwise, I guess this is possible in HQL right?
thanks Sammyrulez for the code. got an idea from that. tested it but it didn't work. i fixed it and here's the final working code:
def ids = [14400 as long, 14401 as long]
def c = VolunteerOpportunity.createCriteria()
def matchingActs = c.list {
node {
eq('type', 'act')
not { 'in'(ids) }
}
maxResults(10)
}
now i know how to use 'not' operator. thanks a lot!
not tried it myself but looking at the Grails doc and hibernate api you create nodes on this builder map with the static methods found in the Restrictions class of the Hibernate Criteria API 1. So something like
def c = VolunteerOpportunity.createCriteria()
def matchingActs = c.list {
node {
not(in('propertyName', ['val1','val2']))
}
maxResults(10)
}
Since you chain the in method (that returns a Criterion) with the not method (that takes a Criterion as argument and returns a negated version)
this is the solution :
def resultat=EnteteImputationBudgetaire.createCriteria().get{
between("dateDebutPeriode", dateDebut, dateFin)
and{ eq 'natureImputationBudgetaire','FONCTIONNEMENT' }
maxResults(1)
}
def resultat2=ParametragePlanBudgetaire.createCriteria().list() {
like('composantBudgetaire','6%')
if(resultat?.details) {
not {
'in'('composantBudgetaire',resultat?.details?.imputationBudgetaire)
}
}
}
According to Grails documentation about creating criteria here, you can use something like this:
not {'in'("age",[18..65])}
In this example, you have a property named "age" and you want to get rows that are NOT between 18 and 65. Of course, the [18..65] part can be substituted with any list of values or range you need.
Just remembering: in this case you don't have to use parenthesis and you can use inList, for example:
not { inList 'age',[18..65] }