MongoDB

Camel MongoDB component

Available as of Camel 2.10

According to Wikipedia: "NoSQL is a movement promoting a loosely defined class of non-relational data stores that break with a long history of relational databases and ACID guarantees." NoSQL solutions have grown in popularity in the last few years, and major extremely-used sites and services such as Facebook, LinkedIn, Twitter, etc. are known to use them extensively to achieve scalability and agility.

Basically, NoSQL solutions differ from traditional RDBMS (Relational Database Management Systems) in that they don't use SQL as their query language and generally don't offer ACID-like transactional behaviour nor relational data. Instead, they are designed around the concept of flexible data structures and schemas (meaning that the traditional concept of a database table with a fixed schema is dropped), extreme scalability on commodity hardware and blazing-fast processing.

MongoDB is a very popular NoSQL solution and the camel-mongodb component integrates Camel with MongoDB allowing you to interact with MongoDB collections both as a producer (performing operations on the collection) and as a consumer (consuming documents from a MongoDB collection).

MongoDB revolves around the concepts of documents (not as is office documents, but rather hierarchical data defined in JSON/BSON) and collections. This component page will assume you are familiar with them. Otherwise, visit http://www.mongodb.org/.

URI format

mongodb:connectionBean?database=databaseName&collection=collectionName&operation=operationName[&moreOptions...]

Endpoint options

MongoDB endpoints support the following options, depending on whether they are acting like a Producer or as a Consumer (options vary based on the consumer type too).

MongoDB operations - producer endpoints

Query operations

findById

This operation retrieves only one element from the collection whose _id field matches the content of the IN message body. The incoming object can be anything that has an equivalent to a BSON type. See http://bsonspec.org/#/specification and http://www.mongodb.org/display/DOCS/Java+Types.

from("direct:findById")
    .to("mongodb:myDb?database=flights&collection=tickets&operation&operation=findById")
    .to("mock:resultFindById");

findOneByQuery

Use this operation to retrieve just one element from the collection that matches a MongoDB query. The query object is extracted from the IN message body, i.e. it should be of type DBObject or convertible to DBObject. See [Type conversions].

from("direct:findOneByQuery")
    .to("mongodb:myDb?database=flights&collection=tickets&operation&operation=findOneByQuery")
    .to("mock:resultFindOneByQuery");

findAll

The findAll operation returns all documents matching a query, or none at all, in which case all documents contained in the collection are returned.

from("direct:findAll")
    .to("mongodb:myDb?database=flights&collection=tickets&operation=findAll")
    .to("mock:resultFindAll");

Paging and efficient retrieval is supported via the following headers:

Additionally, you can set a sortBy criteria by putting the relevant DBObject describing your sorting in the CamelMongoDbSortBy header, quick constant: MongoDbConstants.SORT_BY.

The findAll operation will also return the following OUT headers to enable you to iterate through result pages if you are using paging:

Specifying a field filter

Query operations will, by default, return matching objects in their entirety. If your documents are large and you are only interested in retrieving a subset of their fields, you can specify a field filter in all query operations, simply by setting the relevant DBObject (or type convertible to DBObject, such as a JSON String, Map, etc.) on the CamelMongoDbFieldsFilter header, constant shortcut: MongoDbConstants.FIELDS_FILTER.

An example that uses MongoDB's BasicDBObjectBuilder to simplify the creation of DBObjects:

DBObject fieldFilter = BasicDBObjectBuilder.start().add("_id", 0).add("fixedField", 0).get();
Object result = template.requestBodyAndHeader("direct:findAll", (Object) null, MongoDbConstants.FIELDS_FILTER, fieldFilter);

Create/update operations

insert

Inserts an new object into the MongoDB collection, taken from the IN message body. Type conversion is attempted to turn it into DBObject or a List.
Two modes are supported: single insert and multiple insert. For multiple insert, the endpoint will expect a List, Array or Collections of objects of any type, as long as they are - or can be converted to - DBObject. All objects are inserted at once. The endpoint will intelligently decide which backend operation to invoke (single or multiple insert) depending on the input.

Example:

from("direct:insert")
    .to("mongodb:myDb?database=flights&collection=tickets&operation=insert");

The operation will return a WriteResult, and depending on the WriteConcern or the value of the invokeGetLastError option, the getLastError would have been called already or not. If you want to access the ultimate result of the write operation, you need to retrieve the CommandResult by calling getLastError() or getCachedLastError() on the WriteResult. Then you can verify the result by calling CommandResult.ok(), CommandResult.getErrorMessage() and/or CommandResult.getException().

Note that the new object's _id must be unique in the collection. If you don't specify the value, MongoDB will automatically generate one for you. But if you do specify it and it is not unique, the insert operation will fail (and for Camel to notice, you will need to enable invokeGetLastError or set a WriteConcern that waits for the write result). This is not a limitation of the component, but it is how things work in MongoDB for higher throughput. If you are using a custom _id, you are expected to ensure at the application level that is unique (and this is a good practice too).

save

The save operation is equivalent to an upsert (UPdate, inSERT) operation, where the record will be inserted if it doesn't exist, or else it will be updated. MongoDB will perform the matching based on the _id field.

Beware that in case of an update, the object will be replaced entirely and the usage of MongoDB's $modifiers is not permitted. Therefore, if you want to manipulate the object if it already exists, you have two options:

1. perform a query to retrieve the entire object first along with all its fields (may not be efficient), alter it inside Camel and then save it.
2. use the update operation with $modifiers, which will execute the update at the server-side instead. You can enable the upsert flag, in which case if an insert is required, MongoDB will apply the $modifiers to the filter query object and insert the result.

For example:

from("direct:insert")
    .to("mongodb:myDb?database=flights&collection=tickets&operation=save");

update

Update one or multiple records on the collection. Requires a List<DBObject> as the IN message body containing exactly 2 elements:

• Element 1 (index 0) => filter query => determines what objects will be affected, same as a typical query object
• Element 2 (index 1) => update rules => how matched objects will be updated. All modifier operations from MongoDB are supported.

A header with key CamelMongoDbRecordsAffected will be returned (MongoDbConstants.RECORDS_AFFECTED constant) with the number of records updated (copied from WriteResult.getN()).

Supports the following IN message headers:

For example, the following will update all records whose filterField field equals true by setting the value of the "scientist" field to "Darwin":

// route: from("direct:update").to("mongodb:myDb?database=science&collection=notableScientists&operation=update");
DBObject filterField = new BasicDBObject("filterField", true);
DBObject updateObj = new BasicDBObject("$set", new BasicDBObject("scientist", "Darwin"));
Object result = template.requestBodyAndHeader("direct:update", new Object[] {filterField, updateObj}, MongoDbConstants.MULTIUPDATE, true);

Delete operations

remove

Remove matching records from the collection. The IN message body is expected to be a DBObject or a type convertible to it, and will act as the removal filter query.
The following code will remove all objects whose field 'conditionField' equals true, in the science database, notableScientists collection.

// route: from("direct:remove").to("mongodb:myDb?database=science&collection=notableScientists&operation=remove");
DBObject conditionField = new BasicDBObject("conditionField", true);
Object result = template.requestBody("direct:remove", conditionField);

A header with key CamelMongoDbRecordsAffected will be returned (MongoDbConstants.RECORDS_AFFECTED constant) with the number of records deleted (copied from WriteResult.getN()).

Other operations

count

getDbStats

getColStats

Dynamic operations

An Exchange can override the endpoint's fixed operation by setting the CamelMongoDbOperation header, defined by the MongoDbConstants.OPERATION_HEADER constant.
The values supported are determined by the MongoDbOperation enumeration and match the accepted values for the operation parameter on the endpoint URI.

For example:

Object result = template.requestBodyAndHeader("direct:insert", "irrelevantBody", MongoDbConstants.OPERATION_HEADER, "count");
assertTrue("Result is not of type Long", result instanceof Long);

Type conversions