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).
Name |
Default Value |
Description |
Producer |
Tailable Cursor Consumer |
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none |
Required. The name of the database to which this endpoint will be bound. All operations will be executed against this database unless dynamicity is enabled and the |
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none |
Required. The name of the collection (within the specified database) to which this endpoint will be bound. All operations will be executed against this database unless dynamicity is enabled and the |
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none |
Required for producers. The id of the operation this endpoint will execute. Pick from the following:
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true |
Determines whether the collection will be automatically created in the MongoDB database during endpoint initialisation if it doesn't exist already. If this option is |
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false (behaviour may be inherited from connections WriteConcern) |
Instructs the MongoDB Java driver to invoke |
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none (driver's default) |
Set a |
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none |
Sets a custom |
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none |
Sets a |
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false |
If set to true, the endpoint will inspect the |
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false |
Enables or disables persistent tail tracking for Tailable Cursor consumers. See below for more information. |
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none |
Required if persistent tail tracking is enabled. The id of this persistent tail tracker, to separate its records from the rest on the tail-tracking collection. |
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none |
Required if persistent tail tracking is enabled. Correlation field in the incoming record which is of increasing nature and will be used to position the tailing cursor every time it is generated. The cursor will be (re)created with a query of type: tailTrackIncreasingField > lastValue (where lastValue is possibly recovered from persistent tail tracking). Can be of type Integer, Date, String, etc. NOTE: No support for dot notation at the current time, so the field should be at the top level of the document. |
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1000ms |
Establishes how long the endpoint will wait to regenerate the cursor after it has been killed by the MongoDB server (normal behaviour). |
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same as endpoint's |
Database on which the persistent tail tracker will store its runtime information. |
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camelTailTracking |
Collection on which the persistent tail tracker will store its runtime information. |
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lastTrackingValue |
Field in which the persistent tail tracker will store the last tracked value. |
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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");
Supports fields filter
This operation supports specifying a fields filter. See [Specifying a fields filter#FieldsFilter].
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");
Supports fields filter
This operation supports specifying a fields filter. See [Specifying a fields filter#FieldsFilter].
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:
Header key |
Quick constant |
Description (extracted from MongoDB API doc) |
Expected type |
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Discards a given number of elements at the beginning of the cursor. |
int/Integer |
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Limits the number of elements returned. |
int/Integer |
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Limits the number of elements returned in one batch. A cursor typically fetches a batch of result objects and store them locally. If batchSize is positive, it represents the size of each batch of objects retrieved. It can be adjusted to optimize performance and limit data transfer. If batchSize is negative, it will limit of number objects returned, that fit within the max batch size limit (usually 4MB), and cursor will be closed. For example if batchSize is -10, then the server will return a maximum of 10 documents and as many as can fit in 4MB, then close the cursor. Note that this feature is different from limit() in that documents must fit within a maximum size, and it removes the need to send a request to close the cursor server-side. The batch size can be changed even after a cursor is iterated, in which case the setting will apply on the next batch retrieval. |
int/Integer |
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:
Header key |
Quick constant |
Description (extracted from MongoDB API doc) |
Data type |
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Number of objects matching the query. This does not take limit/skip into consideration. |
int/Integer |
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Number of objects matching the query. This does not take limit/skip into consideration. |
int/Integer |
Supports fields filter
This operation supports specifying a fields filter. See [Specifying a fields filter#FieldsFilter].
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 is 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:
- 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.
- 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 $modifiers to the filter query object and insert the result.
For example:
from("direct:insert") .to("mongodb:myDb?database=flights&collection=tickets&operation=save");
update
Update one or multiple records on the collection. Requires a List<DBObject> as the IN message body containing exactly 2 elements:
- Element 1 (index 0) => filter query => determines what objects will be affected, same as a typical query object
- Element 2 (index 1) => update rules => how matched objects will be updated. All modifier operations from MongoDB are supported.
Multiupdates
By default, MongoDB will only update 1 object even if multiple objects match the filter query. To instruct MongoDB to update all matching records, set the CamelMongoDbMultiUpdate
IN message header to true
.
A header with key CamelMongoDbRecordsAffected
will be returned (MongoDbConstants.RECORDS_AFFECTED
constant) with the number of records updated (copied from WriteResult.getN()
).
Supports the following IN message headers:
Header key |
Quick constant |
Description (extracted from MongoDB API doc) |
Expected type |
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Ff the update should be applied to all objects matching. See http://www.mongodb.org/display/DOCS/Atomic+Operations |
boolean/Boolean |
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If the database should create the element if it does not exist |
boolean/Boolean |
For example, the following will update all records whose filterField field equals true by setting the value of the "scientist" field to "Darwin":
// route: from("direct:update").to("mongodb:myDb?database=science&collection=notableScientists&operation=update"); DBObject filterField = new BasicDBObject("filterField", true); DBObject updateObj = new BasicDBObject("$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 will act as the removal filter query, and is expected to be of type DBObject
or a type convertible to it.
The following example 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
is returned (MongoDbConstants.RECORDS_AFFECTED
constant) with type int
, containing the number of records deleted (copied from WriteResult.getN()
).
Other operations
count
Returns the total number of objects in a collection, returning a Long as the OUT message body.
The following example will count the number of records in the "dynamicCollectionName" collection. Notice how dynamicity is enabled, and as a result, the operation will not run against the "notableScientists" collection, but against the "dynamicCollectionName" collection.
// from("direct:count").to("mongodb:myDb?database=science&collection=notableScientists&operation=count&dynamicity=true"); Long result = template.requestBodyAndHeader("direct:count", "irrelevantBody", MongoDbConstants.COLLECTION, "dynamicCollectionName"); assertTrue("Result is not of type Long", result instanceof Long);
getDbStats
Equivalent of running the db.stats()
command in the MongoDB shell, which displays useful statistic figures about the database.
For example:
> db.stats(); { "db" : "test", "collections" : 7, "objects" : 719, "avgObjSize" : 59.73296244784423, "dataSize" : 42948, "storageSize" : 1000058880, "numExtents" : 9, "indexes" : 4, "indexSize" : 32704, "fileSize" : 1275068416, "nsSizeMB" : 16, "ok" : 1 }
Usage example:
// from("direct:getDbStats").to("mongodb:myDb?database=science&collection=notableScientists&operation=getDbStats"); Object result = template.requestBody("direct:getDbStats", "irrelevantBody"); assertTrue("Result is not of type DBObject", result instanceof DBObject);
The operation will return a data structure similar to the one displayed in the shell, in the form of a DBObject
in the OUT message body.
getColStats
Equivalent of running the db.collection.stats()
command in the MongoDB shell, which displays useful statistic figures about the collection.
For example:
> db.camelTest.stats(); { "ns" : "test.camelTest", "count" : 100, "size" : 5792, "avgObjSize" : 57.92, "storageSize" : 20480, "numExtents" : 2, "nindexes" : 1, "lastExtentSize" : 16384, "paddingFactor" : 1, "flags" : 1, "totalIndexSize" : 8176, "indexSizes" : { "_id_" : 8176 }, "ok" : 1 }
Usage example:
// from("direct:getColStats").to("mongodb:myDb?database=science&collection=notableScientists&operation=getColStats"); Object result = template.requestBody("direct:getColStats", "irrelevantBody"); assertTrue("Result is not of type DBObject", result instanceof DBObject);
The operation will return a data structure similar to the one displayed in the shell, in the form of a DBObject
in the OUT message body.
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);
Tailable Cursor Consumer
Type conversions
The MongoDbBasicConverters
type converter included with the camel-mongodb component provides the following conversions:
Name |
From type |
To type |
How? |
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fromMapToDBObject |
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constructs a new |
fromBasicDBObjectToMap |
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fromStringToDBObject |
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uses |
fromAnyObjectToDBObject |
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uses the Jackson library to convert the object to a |
This type converter is auto-discovered, so you don't need to configure anything manually.