new poster here, I found this previous post but it's on C#,
I tried doing this query straight into the java code of a JSP page, for some reason, it doesn't accept the info in the {} of the find() query and just gives out an error...
So peeps, how do I do this in Java:
// retrieve ssn field for documents where last_name == 'Smith':
db.users.find({last_name: 'Smith'}, {'ssn': 1});
Thanks!
PS: why the hell does C# have the nice little .Exclude() and .Include() commands and java doesn't? cries
The java driver follows the exact same API as the shell. Just pass a DBObject containing your field projection as the second argument to find or findOne
As far as I know the official C# driver doesn't expose Include() and Exclude() methods as they violate the standard API.
Related
Using the Elasticsearch High Level REST Client for Java v7.3
I have a few fields in the schema that look like this:
{
"document_type" : ["Utility", "Credit"]
}
Basically one field could have an array of strings as the value. I not only need to query for a specific document_type, but also a general string query.
I've tried the following code:
QueryBuilder query = QueryBuilders.boolQuery()
.must(QueryBuilders.queryStringQuery(terms))
.filter(QueryBuilders.termQuery("document_type", "Utility"));
...which does not return any results. If I remove the ".filter()" part the query returns fine, but the filter appears to prevent any results from coming back. I'm suspecting it's because document_type is a multi-valued array - maybe I'm wrong though. How would I build a query query all documents for specific terms, but also filter by document_type?
I think, the reason is the wrong query. Consider using the terms query instead of term query. There is also a eqivalent in the java api.
Here is a good overview of the query qsl queries and their eqivalent in the high level rest client: https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/java-rest-high-query-builders.html
I am trying to aggregate a MongoDB (3.6) using Morphia (1.3.2).
Currently it is a simple match and unwind to understand Morphia's API.
The problem that I am facing however is related to MongoDB 3.6:
Changed in version 3.4: MongoDB 3.6 removes the use of aggregate command without the cursor option unless the command includes the explain option. Unless you include the explain option, you must specify the cursor option.
This paragraph comes directly from the MongoDB documentation. MongoDB Aggregate.
This means that a cursor is mandatory for the aggregate to work. However, I can't find a way to do this using Morphia. Therefore my aggregate does not work.
AggregationPipeline data = aggregation.match(query).unwind("data");
Iterator<LoraHourData> out = data.aggregate(Data.class);
The error that is produced using above code is as follows :
Command failed with error 9: The cursor option is required, except for aggregate with the explain argument on server localhost:27017. The full response is { ok : 0.0, errmsg: The cursor option is required, except for aggregate with the explain argument", code : 9, codeName : FailedToParse }
I'm trying to make custom spring Data query using field from reference as query
parameter. When i performed this query via REST i had no results at all:
I enabled hibernate logs and copy it to H2 console and I got many results:
My Flight and Airport entities are very simple
So what am I doing wrong? I have other simpler methods and they work fine using browser. I tried the same using Query annotation(second method on second screen), but I got same results. (Copied generated sql query to H2 console and received many results but it didn't work via REST).
EDIT
I found the solution. I just removed quotation marks from URL and
it works well :D
Sorry for my inattention.
Regards,
Michal
I found the solution. It was very simple. Basically I just removed quotation marks from URL and it works well :D
Actual method in Repository looks like:
List findFlightsByFromCityAndToCity(#Param("from") String from, #Param("to") String to);
Regards,
Michal
I know I can get the AST using the explain extended command. My question is, how to get the same using the Java API.
My goal is to get the following data about queries:
Database source and target (if applied).
Table source and target (if applied).
Fields involved in the query.
I know I can get them above data directly from query string using Regex, but I want to use Java API.
Do you have any other idea how to do that?
You can use Hive Parser for this. It simply takes the query and convert it into AST which is similar explain command. Here is a simple example:
ParseDriver pd = new ParseDriver();
ASTNode tree = pd.parse("Select * from table1");
System.out.println(tree.dump());
The output for this will be
nil
TOK_QUERY
TOK_FROM
TOK_TABREF
TOK_TABNAME
table1
TOK_INSERT
TOK_DESTINATION
TOK_DIR
TOK_TMP_FILE
TOK_SELECT
TOK_SELEXPR
TOK_ALLCOLREF
<EOF>
In twitter by using lang operator you can search for retrieving tweets from a particular language: For example, the following search will return tweets only in english:
https://twitter.com/search?q=lang:en
Is there a way to achieve this using twitter api, especially using twitter4j. I know there is a language attribute for search but it also requires at least one keyword to make a search, I would like to search by a particular language without giving any keyword query. The following command in java driver returns the following error:
Query searchQuery = new Query() //
.count(resultsPerPage) //
.since(since)//
.lang("en");
400:The request was invalid. An accompanying error message will explain why. This is the status code will be returned during version 1.0 rate limiting(https://dev.twitter.com/pages/rate-limiting). In API v1.1, a request without authentication is considered invalid and you will get this response.
message - Query parameters are missing
code - 25
Cheers
You must pass the same do you use in the twitter search, your query will be like:
new Query("lang:en")
Using twitter4j,
Query query = new Query();
query.setLang("en");
query.setQuery(searchQuery);