I am working on a Spring-MVC application in which I would like to search in the database for a combination of options which the user selects. So let's say that there are 10 options, and if user selects 7 of them, how can I effectively write a single method in DAO with a single query which can adapt to the number of options. Kindly see the image below :
As you can see on the left hand side, there are multiple options and the user can select whichever the user chooses. I am looking for something similar where I have created a Search object entity and this entity I would like to pass to dao, where its variables will be extracted and search executed in database.
But if there are even like 3 variables, I see the query looking as :
Pseudo code :
public ResultObject doSearch(var1, var3, var3){
if((var1==true)){
// hibernate query for search where var1 equals true
}
if(!(var2==null)&&(var1==true)){
//Hibernate query for search where var2 is set by user and var1 is true
}
}
But if I keep it doing it in such a horrible fashion, I will never finish. What is the way to handle multiple variables for search when only the ones set should be included and others discarded. Kindly let me know. Thanks.
Use a StringBuilder. As long as the variables are independent from each other this should be easier.
StringBuilder sb = new StringBuilder();
sb.append("FROM phone WHERE 1=1 ");
if (var1) {
sb.append(" AND var1 = :var1");
}
if (var2) {
sb.append(" AND var2 = :var2 ");
}
sb.toString();
Related
I need to optimize a query that iterates over several objects and I wanted Spring Data to let the database handle it. I want to end up with a HashMap<String,String> that looks like
2134_9877, 9877
2134_2344, 2344
3298_9437, 9437
The SQL would be select convert(varchar,b.id)+'_'+convert(varchar,a.id)',a.id from t1 a join t2 b on a.jc = b.jc
So far, I've got Whatever-QL in the repository that looks like:
#Query("SELECT new map (a.bkey, a.akey) FROM mergeTable a WHERE a.discr= ?1")
The problem is, bkey is not unique, it is only unique when paired with akey and the monstrosity that I have to feed it to wants them combined with an underscore: 2345_2177.
I have tried a.bkey.toString and ''+a.bkey and new String(a.bkey) and just string(a.bkey) (that last gives a new exception but still doesn't work) but Spring doesn't like any of these. I can find no questions asking this and it seems I cannot use SQLServer's convert() function as this ain't SQL.
How can I concatenate the Integers as Strings with an underscore in this #Query?
PS: Using the native query that's been debugged in SQLServer throws some weird alias exception in Hibernate so I think 'going native' is predetermined to be a dead end.
If I have understood it right, the 'Whatever-QL' is called JPQL, and the operator CONCAT can be used. Only the use of it, as it accepts two or more parameters depends on the JPA version you are running.
Here is the answer.
JPA concat operator
You could add a getter to your entity like this:
public String getCombinedKey(){
return a.akey + "_" + a.bkey;
}
The advantage is you could handle here null's and other things if you want and it's more reusable in case you need this in another place. If you do it just in the repository you will have to copy it everytime.
Your query would then be:
#Query("SELECT new map (a.combinedKey, a.akey) FROM mergeTable a WHERE a.discr= ?1")
Here's the deal:
public static List<Survey> getFilteredSurveys(Municipality municipality, Company company) {
String sql = "SELECT DISTINCT id FROM survey INNER JOIN " +
"(SELECT SURVEY_ID FROM publicity INNER JOIN brand "+
"ON publicity.brand_id=brand.id WHERE brand.company_id="+company.getId()+") "+
"ON survey_id=survey.id WHERE survey.municipality_id="+municipality.getId();
RawSql rawSql = RawSqlBuilder.parse(sql).create();
List<Survey> surveys = Ebean.find(Survey.class).setRawSql(rawSql).findList();
for (Survey survey : surveys) {
List<Publicity> publicities = new ArrayList<>();
for (Publicity publicity : survey.publicities) {
if(publicity.getBrand().getCompany() == company){
publicities.add(publicity);
}
}
survey.setPublicities(publicities);
}
return surveys;
}
This app is meant for measuring Publicities in a given place,
So people upload a 'Survey' of a place containing all the 'Publicity' that place has.
That function is supposed to return a List,
Each Survey has a List,
And each Publicity has a Brand, which is associated to a Company (ex. Coke -> Coca Cola Co.)
What I'm trying to do is this:
Given a Company, show all the surveys that contain a 'Coca Cola Co.' publicity, but showing only the publicities that belong to 'Coca Cola Co.'
I have a 'Surveys' controller which receives a form with a Municipality and a Company, calls this method, and it renders a view with its result.
This is part of the view template:
#(surveys: java.util.List[Survey])
#for(survey <- surveys){
#for(publicity <- survey.getPublicities){
<tr>
<td>#publicity.getBrand.getName</td>
<td>#publicity.getType.getName</td>
<td>#publicity.getSquareMeters</td>
</tr>
}
}
Problem: even though I removed some publicities from each Survey, all the publicities show up in the view. Why is this happening?
I know I'm not persisting the changes, and I don't want to, I just want to temporarily obfuscate the data so the user only sees the publicities that belong to a given company.
Why isn't this view using the surveys as they are given to it, modified?
Actually I'll put this in an answer ...
You should look at the SQL executed in the log (because I suspect you are getting N+1) here and you could fairly easily avoid that.
You should probably look to change your raw sql to include the publicities columns in the select clause (name, type, squareMeters) to avoid the extra queries.
Alternatively you could add fetch("publicities") to the query (so that they are fetched eagerly via a query join 100 at a time).
Also refer to:
https://github.com/ebean-orm/avaje-ebeanorm/issues/223
... RawSql that includes a OneToMany not working
https://github.com/ebean-orm/avaje-ebeanorm/issues/224
... Enhancement adding RawSqlBuilder.tableAliasMapping()
Ideally you'd be able to use 4.5.2 and take advantage of that fix and that enhancement.
So, I found a fix,
My fix was:
for (Survey survey : surveys) {
survey.getAddress(); //This line fixes the issue
List<Publicity> publicities = new ArrayList<>();
for (Publicity publicity : survey.publicities) {
if(publicity.getBrand().getCompany() != null){
if(publicity.getBrand().getCompany().getId().equals(company.getId())){
publicities.add(publicity);
}
}
}
survey.setPublicities(publicities);
}
My guess is that the problem resides in the way ebean lazily instantiates objects, despite setting Publicities to FetchType.EAGER, and the fact that the output from this function was the expected one, also inspecting surveys in the controller seemed to be ok, and also a #println(surveys) in the view showed only the publicities corresponding to the company I had selected.
How do you implement automatically generated database (let it be SQL) requests?
Let us have offline shop with filters:
The database is standalone offline.
SO if I want to filter items by Price the request would be something like:
select Snowboard.Name
from Snowboard
where Snowboard.Price between 400 and 600;
And if I filter by two characteristics e.g. Price from and Camber. There would be:
select s.Name, s.Camber
from Snowboard s
where s.Price between 400 and 600
and s.Camber in ('Rocker', 'Hybrid');
The question is how could it be implemented in Java so that these requests are generated automatically from any combination of filters selected?
Quick and dirty solution #1
Generate a query at run time & make clever use of WHERE 1=1 condition as the number of where clause are unknown. (This sample is in C# but works more or less the same with JAVA as well)
string sql= #"select Snowboard.Name
from Snowboard
where 1=1";
Now you can build your query based on the UI element selections like
string whereClause="";
if(yourCheckBoxPrice.Checked)
{
whereClause+= " AND Price BETWEEN "+ txtPriceFrom.Text + " AND "+ txtPriceTo.Text;
}
if(yourCheckBoxCamber.Checked)
{
whereClause+= " AND Camber IN ("+ /* your list of values go here */ +")";
}
sql += whereClause;
2nd Solution (Use SQL CASE)
You can use SQL CASE inside your query for each where clause to check for nulls or specific values. But beware, dynamic SQL will make your code pretty messy & hard to read (Can be done via a stored procedure as well)
SQL- CASE Statement
I advise you to use a stored procedure with a mix of both options 1 and 2. Implementing Dynamic SQL Where Clause. Keep it simple and you are good to go.
I'm new to Liferay development in general, so feel free to point out if I'm going about stuff totally the wrong way.
I'm trying to get a DynamicQuery object of all users within a certain group (I'll use this object to further filter another query I'll do against the message board). The User interface seems to have a roleIds property that I might be able to use, since I already know the roleId I'm interested in. But I can't find the proper way to query if roleIds contains a certain value.
Any ideas on what I want to do?
PS: I would have the exact SQL query I could ask directly, but I'd rather use Liferay's own connection pool, without needing to do some weird ext project thingy.
You don't need a DynamicQuery. These are the methods you are looking for in the classes that Dirk points out:
long[] UserServiceUtil.getRoleUserIds(long roleId)
or
long[] UserLocalServiceUtil.getRoleUserIds(long roleId)
List<User> UserLocalServiceUtil.getRoleUsers(long roleId)
Remember that the methods in the classes XXXLocalServiceUtil are not checking the permissions of the current user.
EDIT: If you are looking for all users with a given role within a given community:
long companyId= _X_; //Perhaps CompanyThreadLocal.getCompanyId() if you don't have it anywhere else?
Role role=RoleLocalServiceUtil.getRole(companyId, "Example Role");
Group group=GroupLocalServiceUtil.getGroup(companyId, "Example Community");
List<UserGroupRole> userGroupRoles = UserGroupRoleLocalServiceUtil.
getUserGroupRolesByGroupAndRole(groupId, role.getRoleId());
for(UserGroupRole userGroupRole:userGroupRoles){
User oneUser=userGroupRole.getUser();
}
The easiest way to access liferays own objects is by using the XXXServiceUtil classes (e.g. RoleServiceUtil.getUserRoles(userId)). Thus you rarely have to deal with any SQL directly. Either the RoleServiceUtil or UserServiceUtil might have what you need.
The roles of an Organizations are stored in the table UserGroupRole, so if you want to get the owner of an Organization you must use the following code:
boolean isOrgOwner =
UserGroupRoleLocalServiceUtil.hasUserGroupRole(
usr.getUserId(),
this.currentOrganization.getGroupId(),
RoleConstants.ORGANIZATION_OWNER);
If you want to retrieve all the Organization Owners of an organization:
List<User> administrators = new LinkedList<>();
List<UserGroupRole> allOrganizationAdministrators =
UserGroupRoleLocalServiceUtil.getUserGroupRolesByGroupAndRole(
this.currentOrganization.getGroupId(), roleId);
for (UserGroupRole userGroupRoleTemp : allOrganizationAdministrators) {
administrators.add(userGroupRoleTemp.getUser());
}
Cheers!
Hello guys I am having some problems with exact matches while doing a NamedQuery.
I am currently using something like this:
#NamedQuery(name = MyClass.GET_ENTRY_BY_NAME, query = "select e from Entry e where e.name =:"+ Entry.NAME )
...
Query query = em.createNamedQuery(MyClass.GET_ENTRY_BY_NAME);
query.setParameter(Entry.NAME, myEntry.getName());
It works for most cases, however I noticed that in case the user pass the file name with an space at the end, the namedQuery ignores that character. For example:
Query query = em.createNamedQuery(MyClass.GET_ENTRY_BY_NAME);
query.setParameter(Entry.NAME, myEntry.getName()+ " ");
Will return the same result as the query before. Bypassing my 'valid entry' validation. In other words I'd like the query to return no entry at all and treat the error later on.
One workaround I could think of, is to put single quotes surrounding my parameter in the namedQuery, like this:
#NamedQuery(name = MyClass.GET_ENTRY_BY_NAME, query = "select e from entry e where e.name =':"+ Entry.NAME "'")
However it will trash my code in case the String contains single quotes in it...
Any ideas guys?
I guess this happens because your database field is declared as CHAR(...), and therefore stored values are padded with whitespaces which are not taken into account by = operation.
So, you may either declare your database field as VARCHAR(...) or use a built-in trim function:
query = "select e from Entry e where trim(trailing from e.name) =:"+ Entry.NAME
I did some research in JPA and found out that it does some automatic trimming for CHARs, I am not sure if this behaves the same with Strings, but since it is happening to me... I believe so. The only way to bypass it is by setting some attribute within the session DatabaseLogin object (see http://www.eclipse.org/eclipselink/api/1.1/org/eclipse/persistence/sessions/DatabaseLogin.html#setShouldTrimStrings) .
Well I didn't want to be messing up with the session properties so I decided to make some sort of check and throwing the same exception as the NoResultException catch does in my code.
I basically took the result from the database and compared the field with the String I used:
query.setParameter(Entry.NAME, myEntry.getName());
...
if(!StringUtils.equals(result.getName(), myEntry.getName()){
do a cool throw just like NoResultException Catch
}
I also had to include the Trim function axtavt! This is just to make sure that if the database has a column with trailing spaces and it matches the parameter given by the user, it will be included as a valid answer. For example:
Database entry: Name = "Flavio " - Trimmed with Function = "Flavio".
Parameter passed: Name = "Flavio " - Trimmed by JPA automatic function = "Flavio".
If it isnt trimmed at all it will just Compare "Flavio " with "Flavio", returning NoResult when it was supposed to return that Entry.
Nasty workaround, but as long as there is no other way to stop the auto-trimming we will have to just make use of this sort of things.
Thanks for all the other answers!!