we have Spring Hibernate code which generates a Spring JPA data Specification object. This works well (we can use the Specification object to do things like get count). Is there a way to get a plain SQL where-clause from the specification object somehow?
The current code is:
// The line below builds the spec based on business logic. Won't go in the details here, but it is working.
Specification<Crash> querySpec = buildQuerySpec(query);
long count = myDataRepository.count(querySpec);
// Here is what I need: a simple plain T-SQL / Microsoft SQL Server where-clause to be used on other disconnected systems. So something like this:
String whereClause = query.Spec.getPlainSQLWhereClause(...); // e.g. weather in ("raining", "cold") and year in (2014, 2015)
Reason: the specification object (and its related repository) are used in the main system. Now we have other completely disconnected/separate enterprise systems (Esri GIS system), where its APIs can only use plain SQL where-clause.
P.S. I know there's not much code to work with, so some pointers/guides will be much appreciated.
I'm new user of mongoDB, I have create an application with spring boot/mySql and I want replace database sql to mongoDB.
I did change all things necessary for example, annotations, relations etc ... but I have a problem with request I don't know the similar syntax of #Query in mongoDb.
this my request with sql:
// this calculate the sum of all distance in walk's document
#Query("select sum(distance) from Walk")
public Double sumDistance();
I did read mongoDB aggregate and I know how to use it in console windows with command
$ mongo
$ db.walk.aggregate([{$group:{"_id":"$dateWalk",Count:{$sum:"$distance"}}}])
but, I want use $sum in my program java not in console.
So please, I need your help about the syntax similar to this with mongoDB
// this calculate the sum of all distance in walk's document
#Query("select sum(distance) from Walk")
public Double sumDistance();
thanks in advance :)
You would need to create a custom Repository that would implement the aggregation.
Examples:
https://www.javacodegeeks.com/2016/04/data-aggregation-spring-data-mongodb-spring-boot.html
https://github.com/spring-projects/spring-data-examples/blob/master/mongodb/aggregation/src/main/java/example/springdata/mongodb/aggregation/OrderRepositoryImpl.java
I have a solr field visibility that has a set of possible values and I would like to perform a search using Spring Data Solr. I'd like to use in() and boost some but not all values if possible.
Here's an example of the search I need,
visibility:(visible^1000 archived)
or
visibility:(visible^1000 draft^500 archived)
Would this be possible in version 1.0.0.RELEASE or later versions? Currently I'm using 1.0.0.RELEASE.
Thanks, /w
I never managed to chain this query properly, but was enlightened by petrikainulainen.net on SimpleStringCriteria().
Criteria criteria = new SimpleStringCriteria("(visibility:(visible^1000) OR visibility:(draft^500) OR visibility:(archived))");
By doing as shown below you will give far higher boost to the docs that has the category as 'webpage'. Then add 'combined' criteria to your existing other criteria
Criteria webpage= new Criteria("category" ).is("webpage" ).boost((float) 1000);
Criteria document= new Criteria("category" ).is("document" ).boost((float) 2);
Criteria combined= webpage.or( document);
I am new to ElasticSearch and Couchbase. I am building a sample Java application to learn more about ElasticSearch and Couchbase.
Reading the ElasticSearch Java API, Filters are better used in cases where sort on score is not necessary and for caching.
I still haven't figured out how to use FilterBuilders and have following questions:
Can FilterBuilders be used alone to search?
Or Do they always have to be used with a Query? ( If true, can someone please list an example? )
Going through a documentation, if I want to perform a search based on field values and want to use FilterBuilders, how can I accomplish that? (using AndFilterBuilder or TermFilterBuilder or InFilterBuilder? I am not clear about the differences between them.)
For the 3rd question, I actually tested it with search using queries and using filters as shown below.
I got empty result (no rows) when I tried search using FilterBuilders. I am not sure what am I doing wrong.
Any examples will be helpful. I have had a tough time going through documentation which I found sparse and even searching led to various unreliable user forums.
private void processQuery() {
SearchRequestBuilder srb = getSearchRequestBuilder(BUCKET);
QueryBuilder qb = QueryBuilders.fieldQuery("doc.address.state", "TX");
srb.setQuery(qb);
SearchResponse resp = srb.execute().actionGet();
System.out.println("response :" + resp);
}
private void searchWithFilters(){
SearchRequestBuilder srb = getSearchRequestBuilder(BUCKET);
srb.setFilter(FilterBuilders.termFilter("doc.address.state", "tx"));
//AndFilterBuilder andFb = FilterBuilders.andFilter();
//andFb.add(FilterBuilders.termFilter("doc.address.state", "TX"));
//srb.setFilter(andFb);
SearchResponse resp = srb.execute().actionGet();
System.out.println("response :" + resp);
}
--UPDATE--
As suggested in the answer, changing to lowercase "tx" works. With this question resolved. I still have following questions:
In what scenario(s), are filters used with query? What purpose will this serve?
Difference between InFilter, TermFilter and MatchAllFilter. Any illustration will help.
Right, you should use filters to exclude documents from being even considered when executing the query. Filters are faster since they don't involve any scoring, and cacheable as well.
That said, it's pretty obvious that you have to use a filter with the search api, which does execute a query and accepts an optional filter. If you only have a filter you can just use the match_all query together with your filter. A filter can be a simple one, or a compund one in order to combine multiple filters together.
Regarding the Java API, the names used are the names of the filters available, no big difference. Have a look at this search example for instance. In your code I don't see where you do setFilter on your SearchRequestBuilder object. You don't seem to need the and filter either, since you are using a single filter. Furthermore, it might be that you are indexing using the default mappings, thus the term "TX" is lowercased. That's why when you search using the term filter you don't find any match. Try searching for "tx" lowercased.
You can either change your mapping if you want to keep the "TX" term as it is while indexing, probably setting the field as not_analyzed if it should only be a single token. Otherwise you can change filter, you might want to have a look at a query that is analyzed, so that your query wil be analyzed the same way the content was indexed.
Have a look at the query DSL documentation for more information regarding queries and filters:
MatchAllFilter: matches all your document, not that useful I'd say
TermFilter: Filters documents that have fields that contain a term (not analyzed)
AndFilter: compound filter used to put in and two or more filters
Don't know what you mean by InFilterBuilder, couldn't find any filter with this name.
The query usually contains what the user types in through the text search box. Filters are more way to refine the search, for example clicking on facet entries. That's why you would still have the query plus one or more filters.
To append to what #javanna said:
A lot of confusion can come from the fact that filters can be defined in several ways:
standalone (with a required query, for instance match_all if all you need is the filters) (http://www.elasticsearch.org/guide/reference/api/search/filter/)
or as part of a filtered query (http://www.elasticsearch.org/guide/reference/query-dsl/filtered-query/)
What's the difference you might ask. And indeed you can construct exactly the same logic in both ways.
The difference is that a query operates on BOTH the resultset as well as any facets you have defined. Whereas, a Filter (when defined standalone) only operates on the resultset and NOT on any facets you may have defined (explained here: http://www.elasticsearch.org/guide/reference/api/search/filter/)
To add to the other answers, InFilter is only used with FilterBuilders. The definition is, InFilter: A filter for a field based on several terms matching on any of them.
The query Java API uses FilterBuilders, which is a factory for filter builders that can dynamically create a query from Java code. We do this using a form and we build our query based on user selections from it with checkboxes, options, and dropdowns.
Here is some Example code for FilterBuilders and there is a snippet from that link that uses InFilter as shown below:
FilterBuilder filterBuilder;
User user = (User) auth.getPrincipal();
if (user.getGroups() != null && !user.getGroups().isEmpty()) {
filterBuilder = FilterBuilders.boolFilter()
.should(FilterBuilders.nestedFilter("userRoles", FilterBuilders.termFilter("userRoles.key", auth.getName())))
.should(FilterBuilders.nestedFilter("groupRoles", FilterBuilders.inFilter("groupRoles.key", user.getGroups().toArray())));
} else {
filterBuilder = FilterBuilders.nestedFilter("userRoles", FilterBuilders.termFilter("userRoles.key", auth.getName()));
}
...
I'm having trouble getting objects back out of SimpleDB using the simpleJPA persistance API. I have successfully installed all the jars and can persist objects no problem. However I cannot seem to retrieve objects using select queries - but weirdly I can get results using count queries. There are no errors or exceptions, the queries simply don't return any results. When I debug I can view the actual AWS Query that is being generated in the background by simpleJPA, and when I run this query against a domain it returns the expected results no problem.
I've included my Java code below, it should return me a list of all the users in my database.
Query query = em.createQuery("SELECT u FROM User u");
List<User> results = (List<User>)query.getResultList();
As I said I can persist objects and count them, so there isn't anything wrong with my entity manager or factory, its just returning empty lists. If you need any more information just ask,
Thanks in advance!
I never got to the bottom of this problem. In the end I started a new AWS project in Eclipse and re-added the JAR files, solving the issue.