Search Query¶
The search query is the base query of all queries, which can filter. These are the delete, find, update and replace query. It is used to filter the result on database side.
Query operations¶
Simple selecting¶
The simplest query is to only filter with one collection field.
QueryResult result = collection.find().where("name", "Shepard").execute();
Negation¶
To negate a part of a query, you can use the not method in the query. Then you would write in the query consumer all
the query part on the given position, which should be negated. For some operations, there are default negation method
implementation, so you have a shorter query.
query.not(query -> query.where("name", "Thomas"))
For the where operator and other operators are, as it is explained above shorter ways to build the query. For more
short query parts, see the javadocs.
And/Or queries¶
And and or operations are used to specify multiple conditions for the query. All query parts in these queries are
connected with the keyword.
query.and(query -> query.where("name", "Thomas").where("gender", "MALE"))
query.or(query -> query.where("name", "Thomas").where("name", "Peter"))
Limit the result¶
For limiting the result size, there are several options to use. It is recommended to limit your result size to prevent an out of memory exception on your client.
Warning
You can only use limit one time in the query
query.limit(1000)
To get all results in pagination, there are some useful query tools to make it easier.
query.page(page, entriesPerPage)
You can also get entries with a range of indices.
query.index(startIndex, endIndex)
Order the result¶
There are many use cases to order a result. You can order your result ascending or descending.
Info
You can use order by multiple times in the query
query.orderBy(fieldToOrder, SearchOrder.ASC/DESC)
Also, you can order with an aggregation.
Handling the query result¶
A query results holds multiple result entries. One query has one result with multiple result entries, where one result entry belongs to one single result (In sql typically one row).
Checking size¶
Before you should work with the result entries, you should check if the result has entries.
Note
In this example, only one result entry is got. To get all entries, you should loop through the result
if(!result.isEmpty()) {
//Do some stuff
QueryResultEntry resultEntry = result.first();
}
Getting objects from result entry¶
Every result entry is sorted and one can get values with their index or key.
String name = resultEntry.getString("name");