I've got query that looks something like this:
SomeDomain.executeQuery("""
from
SomeDomain x
where
x.linkToSomeA = coalesce(:a, x.linkToSomeA) and
x.linkToSomeB = coalesce(:b, x.linkToSomeB) and
...
""",
[a: someA, b: someB, ...]
)
The intended behaviour is as follows: once null is supplied for a criterion parameter, this criterion should be ignored. If anything other than null is supplied, the criterion is used.
Everything would work fine, except that Hibernate doesn't allow supplying null where domain class instances are expected. So in the end this is not a valid query (in fact NullPointerException will be thrown if any nulls are supplied).
I haven't found any way to rewrite this without using a ton of if-else. Does anybody have any idea how to make this about equally brief and valid at the same time?
NOTE: The real query is more complicated than that so please, do not suggest rewriting this using anything else than executeQuery.
This is generally for this kind of problem that the Criteria api is used: it allows building a query dynamically:
Criteria c = session.createCriteria(SomeDomain.class, "x");
if (a != null) {
c.add(Restrictions.eq("x.linkToSomeA", a));
}
if (b != null) {
c.add(Restrictions.eq("x.linkToSomeB", b));
}
// ...
This answer doesn't follow your request of not using anything else than executeQuery, but you might also ask how to build a house using nothing else than a screwdriver, and the best answer would still be "buy some other tools").
I'm wondering if you can use a map and findAll(), like this:
def query = [
'a': 'x.linkToSomeA = :a',
'b': 'x.linkToSomeB = :b'
].findAll{ k, q -> params[k] != null }.values().join(' and ')
SomeDomain.executeQuery("""
from
SomeDomain x
where
${query}
""",
params
)
This should return a list of all query elements that have non-null parameters in the params map (this should be changed to match the map used in the query). It's a simple job of filtering out based on the "key" of the main map, then joining the values with and.
Note, there's one potential issue, and that's if there's no params at all. In that case, you'll want to check that query is non-empty or provide a fallback method.
Related
While searching using java api in elaticsearch, I would like to retrieve only one column.
Currently when I query using the Java API it returns the whole record like this: [{_id=123-456-7890, name=Wonder Woman, gender=FEMALE}, {_id=777-990-7890, name=Cat Woman, gender=FEMALE}]
The record above correctly matches the search condition shown in th . As shown in the code below:
List<Map<String, Object>> result = new ArrayList<Map<String, Object>>();
SearchRequestBuilder srb = client.prepareSearch("heros")
.setSearchType(SearchType.DFS_QUERY_THEN_FETCH);
MatchQueryBuilder mqb;
mqb = QueryBuilders.matchQuery("name", "Woman");
srb.setQuery(mqb);
SearchResponse response = srb.execute().actionGet();
long totalHitCount = response.getHits().getTotalHits();
System.out.println(response.getHits().getTotalHits());
for (SearchHit hit : response.getHits()) {
result.add(hit.getSource());
}
System.out.println(result);
I want only one column to be returned. If I search for name I just want the full names back in a list: "Wonder Woman", "Cat Woman" only not the whole json record for each of them. If you think I need to iterate over the result list of maps in java please propose an example of how to do that in this case.
You can specify the fields to be returned from a search, per documentation. This can be set via SearchRequestBuilder.addFields(String... fields), ie:
SearchRequestBuilder srb = client.prepareSearch("heros")
.setSearchType(SearchType.DFS_QUERY_THEN_FETCH)
.addFields("name");
Better combine both:
use .addFields("name") to tell ES that it needs to return only this
column
use hit.field("name").getValue().toString() to get the result
It is important to use .addFields when you don't need the whole document, but the specific field/s as it will lower the overhead and the network traffic
I figured it out.
List<String> valuesList= new ArrayList<String>();
for (SearchHit hit : response.getHits()) {
result.add(hit.getSource());
valuesList.add(hit.getSource().get("name").toString());
}
The other solutions didn't work for me, hit.getSource() was returning null. Maybe they are deprecated? Not sure. But here was my solution, which FYI can speed things up considerably if you are only getting one field and you are getting lots of results.
Use addFields(Strings) on your SearchRequestBuilder as mentioned, but then when you are getting the values you need to use:
hit.getFields().get( fieldName ).getValue()
or
hit.getFields().get( fieldName ).getValues()
to get a single value or a list of values depending on the field.
Maybe I'm really missing something.
I have indexed a bunch of key/value pairs in Lucene (v4.1 if it matters). Say I have
key1=value1 and key2=value2, e.g. as read from a properties file.
They get indexed both as specific fields and into a catchall "ALL" field, e.g.
new Field("key1", "value1", aFieldTypeMimickingKeywords);
new Field("key2", "value2", aFieldTypeMimickingKeywords);
new Field("ALL", "key1=value1", aFieldTypeMimickingKeywords);
new Field("ALL", "key2=value2", aFieldTypeMimickingKeywords);
// then get added to the Document of course...
I can then do a wildcard search, using
new WildcardQuery(new Term("ALL", "*alue1"));
and it will find the hit.
But, it would be nice to get more info, like "what was complete value (e.g. "key1=value1") that goes with that hit?".
The best I can figure out it to get the Document, then get the list of IndexableFields, then loop over all of them and see if the field.stringValue().contains("alue1"). (I can look at the data structures in the debugger and all the info is there)
This seems completely insane cause isn't that what Lucene just did? Shouldn't the Hit information return some of the Fields?
Is Lucene missing what seems like "obvious" functionality? Google and starting at the APIs hasn't revealed anything straightforward, but I feel like I must be searching on the wrong stuff.
You might want to try with IndexSearcher.explain() method. Once you get the ID of the matching document, prepare a query for each field (using the same search keywords) and invoke Explanation.isMatch() for each query: the ones that yield true will give you the matched field. Example:
for (String field: fields){
Query query = new WildcardQuery(new Term(field, "*alue1"));
Explanation ex = searcher.explain(query, docID);
if (ex.isMatch()){
//Your query matched field
}
}
I am using a custom score query with a multiMatchQuery. Ultimately what I want is simple and requires little explaination. In my Java Custom Score Script, I want to be able to find out which field a result matched to.
Example:
If I search Starbucks and a result comes back with the name Starbucks then I want to be able to know that name.basic was the field that matched my query. If I search for coffee and starbucks comes back I want to be able to know that tags was the field that matched.
Is there anyway to do this?
Search Query Code:
def basicSearchableSearch(t: String, lat: Double, lon: Double, r: Double, z: Int, bb: BoundingBox, max: Int): SearchResponse = {
val multiQuery = filteredQuery(
multiMatchQuery(t)
//Matches businesses and POIs
.field("name.basic").operator(Operator.OR)
.field("name.no_space")
//Businesses only
.field("tags").boost(6f),
geoBoundingBoxFilter("location")
.bottomRight(bb.botRight.y,bb.botRight.x)
.topLeft(bb.topLeft.y,bb.topLeft.x)
)
val customQuery = customScoreQuery(
multiQuery
)
.script("customJavaScript")
.lang("native")
.param("lat",lat)
.param("lon",lon)
.param("zoom",z)
global.Global.getClient().prepareSearch("searchable")
.setSearchType(SearchType.DFS_QUERY_THEN_FETCH)
.setQuery(customQuery)
.setFrom(0).setSize(max)
.execute()
.actionGet();
}
It's only simple for simple queries. On complex queries, the question which field matched is actually quite nontrivial. So, I cannot think of any efficient way to do it.
Perhaps, you could consider moving your custom score calculation closer to the match. The multi_match query is basically a shortcut for a set of match queries on the same query string combined by a dis_max query. So, you are currently building something like this:
custom_score(
filtered(
dis_max(match_1, match_2, match_3)
)
)
What you can do is to move your custom_score under dis_max and build something like this:
filtered(
dis_max(
custom_score_1(match_1),
custom_score_2(match_2),
custom_score_3(match_3)
)
)
Obviously, this will be a somewhat different query, since dis_max will operate on custom score instead of original score.
Hy,
Hbase allows a column family to have different qualifiers in different rows. In my case a column family has the following specification
abc[cnt] # where cnt is an integer that can be any positive integer
what I want to achieve is to get all the data from a different column family, only if the value of the described qualifier (in a different column family) matches.
for narrowing the Scan down I just add those two families I need for the query. but that is as far as I could get for now.
I already achieved the same behaviour with a SingleColumnValueFilter, but then the qualifier was known in advance. but for this one the qualifier can be abc1, abc2 ... there would be too many options, thus too many SingleColumnValueFilter's.
Then I tried using the ValueFilter, but this filter only returns those columns that match the value, thus the wrong column family.
Can you think of any way to achieve my goal, querying for a value within a dynamically created qualifier in a column family and returning the contents of the column family and another column family (as specified when creating the Scan)? preferably only querying once.
Thanks in advance for any input.
UPDATE: (for clarification as discussed in the comments)
in a more graphical way, a row may have the following:
colfam1:aaa
colfam1:aab
colfam1:aac
colfam2:abc1
colfam2:abc2
whereas I want to get all of the family colfam1 if any value of colfam2 has e.g. the value x, with regard to the fact that colfam2:abc[cnt] is dynamically created with cnt being any positive integer
I see two approaches for this: client-side filtering or server-side filtering.
Client-side filtering is more straightforward. The Scan adds only the two families "colfam1" and "colfam2". Then, for each Result you get from scanner.next(), you must filter according to the qualifiers in "colfam2".
byte[] queryValue = Bytes.toBytes("x");
Scan scan = new Scan();
scan.addFamily(Bytes.toBytes("colfam1");
scan.addFamily(Bytes.toBytes("colfam2");
ResultScanner scanner = myTable.getScanner(scan);
Result res;
while((res = scanner.next()) != null) {
NavigableMap<byte[],byte[]> colfam2 = res.getFamilyMap(Bytes.toBytes("colfam2"));
boolean foundQueryValue = false;
SearchForQueryValue: while(!colfam2.isEmpty()) {
Entry<byte[], byte[]> cell = colfam2.pollFirstEntry();
if( Bytes.equals(cell.getValue(), queryValue) ) {
foundQueryValue = true;
break SearchForQueryValue;
}
}
if(foundQueryValue) {
NavigableMap<byte[],byte[]> colfam1 = res.getFamilyMap(Bytes.toBytes("colfam1"));
LinkedList<KeyValue> listKV = new LinkedList<KeyValue>();
while(!colfam1.isEmpty()) {
Entry<byte[], byte[]> cell = colfam1.pollFirstEntry();
listKV.add(new KeyValue(res.getRow(), Bytes.toBytes("colfam1"), cell.getKey(), cell.getValue());
}
Result filteredResult = new Result(listKV);
}
}
(This code was not tested)
And then finally filteredResult is what you want. This approach is not elegant and might also give you performance issues if you have a lot of data in those families. If "colfam1" has a lot of data, you don't want to transfer it to the client if it will end up not being used if value "x" is not in a qualifier of "colfam2".
Server-side filtering. This requires you to implement your own Filter class. I believe you cannot use the provided filter types to do this. Implementing your own Filter takes some work, you also need to compile it as a .jar and make it available to all RegionServers. But then, it helps you to avoid sending loads of data of "colfam1" in vain.
It is too much work for me to show you how to custom implement a Filter, so I recommend reading a good book (HBase: The Definitive Guide for example). However, the Filter code will look pretty much like the client-side filtering I showed you, so that's half of the work done.
I'm using hibernate, and trying to do a LIKE on certain fields.
I'm splitting a string, and then generating the HQL, with
table.entry LIKE :argsearch_0 OR table.entry LIKE :argsearch_0 OR
table.entry LIKE :argsearch_1 OR table.entry LIKE :argsearch_1
(0 and 1 is in fact incremented with a counter).
But i get :
Not all named parameters have been set: [argsearch_0]
First question :
Can I used 2 named parameter and do only 1 setParameter (or setString) :
String nameParam = "argsearch_"+i;
q.setParameter(nameParam, "%"+args[i]+"%");
Second question :
Why my parameters are not working ?
Depends what you mean when you ask "Can I used 2 named parameter and do only 1 setParameter".
In your original query you have 2 named parameters ('argsearch_0' and 'argsearch_1') and each has 2 usages in the query. So you have to call set for both 'argsearch_0' and 'argsearch_1'. But you only call set once for each (actually you can call set multiple times for each parameter if you really want, but only the last once is used.
As for your second question, as someone already pointed out, its because you have a bug in your code. You are not setting the value for the 'argsearch_0' parameter.
You can Try this
**Step 1--:** Add How many parameter you need just add in hashmap
-------------------------------------------------------------------
HashMap param_List=new HashMap();
param_List.put("contactNo",22);
**Step 2--:** Just You pass your Query
-------------------------------------------------------------------
Query query1 = session.createQuery("select * from emailTemplate where c.contactNo =:contactNo");
**Step 3--:** What ever Data type is no matters but get an output.
-------------------------------------------------------------------
for(Object paramKey : param_List.keySet())
{
query1.setParameter(paramkey.toString(), param_List.get(paramKey);
}
**Step 4--:**
-------------------------------------------------------------------
String finalResult=query1.getSingleResult().toString();