org.dizitart.no2

Interface Filter

All Known Subinterfaces:

ObjectFilter

All Known Implementing Classes:

BaseFilter, BaseObjectFilter

public interface Filter

An interface to specify filtering criteria during find operation. When a filter is applied to a collection, based on the criteria it returns a set of NitriteIds of matching records.

Each filtering criteria is based on a value of a document. If the value is indexed, the find operation takes the advantage of it and only scans the index map for that value. But if the value is not indexed, it scans the whole collection.

The supported filters are:

Table 1. Comparison Filters

Filter	Method	Description
Equals	Filters.eq(String, Object)	Matches values that are equal to a specified value.
Greater	Filters.gt(String, Object)	Matches values that are greater than a specified value.
GreaterEquals	Filters.gte(String, Object)	Matches values that are greater than or equal to a specified value.
Lesser	Filters.lt(String, Object)	Matches values that are less than a specified value.
LesserEquals	Filters.lte(String, Object)	Matches values that are less than or equal to a specified value.
In	Filters.in(String, Object[])	Matches any of the values specified in an array.

Table 2. Logical Filters

Filter	Method	Description
Not	Filters.not(Filter)	Inverts the effect of a filter and returns results that do not match the filter.
Or	Filters.or(Filter[])	Joins filters with a logical OR returns all ids of the documents that match the conditions of either filter.
And	Filters.and(Filter[])	Joins filters with a logical AND returns all ids of the documents that match the conditions of both filters.

Table 3. Array Filter

Filter	Method	Description
Element Match	Filters.elemMatch(String, Filter)	Matches documents that contain an array field with at least one element that matches the specified filter.

Table 4. Text Filters

Filter	Method	Description
Text	Filters.text(String, String)	Performs full-text search.
Regex	Filters.regex(String, String)	Selects documents where values match a specified regular expression.

Example of various filters

// returns the ids of the documents whose age field value is 30
collection.find(eq("age", 30));

// age field value is greater than 30
collection.find(gt("age", 30));

// age field value is not 30
collection.find(not(eq("age", 30)));

// age field value is 30 and salary greater than 10K
collection.find(and(eq("age", 30), gt("salary", 10000)));

// note field contains the string 'hello'
collection.find(regex("note", "hello"));

// prices field contains price value between 10 to 20
collection.find(elemMatch("prices", and(gt("$", 10), lt("$", 20))));

A nitrite document can contain another document. To specify a field of a nested document a '.' operator is used. If a field is an array or list, array/list index can be used as a field to access a specific element in them.

Example of nested document

NitriteMapper nitriteMapper = new JacksonMapper();

// parse a json into a document
doc = nitriteMapper.parse("{" +
"  score: 1034," +
"  location: {  " +
"       state: 'NY', " +
"       city: 'New York', " +
"       address: {" +
"            line1: '40', " +
"            line2: 'ABC Street', " +
"            house: ['1', '2', '3'] " +
"       }" +
"  }," +
"  category: ['food', 'produce', 'grocery'], " +
"  objArray: [{ field: 1}, {field: 2}]" +
"}");

// insert the doc into collection
collection.insert(doc);

// filter on nested document
collection.find(eq("location.address.line1", "40"));

// filter on array using array index
collection.find(eq("location.address.house.2", "3"));

// filter on object array
collection.find(eq("objArray.0.field", 1));

Since:

1.0

See Also:

NitriteCollection#find(Filter, FindOptions), NitriteCollection#find(Filter), Filters

Method Summary

Modifier and Type	Method and Description
java.util.Set<NitriteId>	apply(NitriteMap<NitriteId,Document> documentMap) Filters a document map and returns the set of NitriteIds of matching Documents.
void	setNitriteService(NitriteService nitriteService) Sets NitriteService in the filter object.

Method Detail

apply

java.util.Set<NitriteId> apply(NitriteMap<NitriteId,Document> documentMap)

Filters a document map and returns the set of NitriteIds of matching Documents.

Parameters:

documentMap - the document map

Returns:

a set of NitriteIds of matching documents.

setNitriteService

void setNitriteService(NitriteService nitriteService)

Sets NitriteService in the filter object.

Parameters:

nitriteService - the nitrite service