MongoDBExecute

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Short Description

MongoDBExecute executes JavaScript commands on the MongoDB™ database. ^[1]

Component	Same input metadata	Sorted inputs	Inputs	Outputs	Each to all outputs	Java	CTL	Auto-propagated metadata
MongoDBExecute	-		0-1	0-2	-

Icon

Ports

Port type	Number	Description	Metadata
Input	0	Input data records to be mapped to component attributes.	any
Output	0	Results	any
Output	1	Errors	any

Metadata

MongoDBExecute does not propagate metadata from left to right or from right to left.

This component has metadata templates available. The templates are described in Details. See general details on Metadata Templates.

MongoDBExecute Attributes

Attribute	Req	Description	Possible values
Basic
Connection		ID of the MongoDB connection to be used.
Command	^{[ 1]}	JavaScript code to be executed on the MongoDB database. Mirrors the syntax used in the `mongo` shell.
Input mapping	^{[ 2]}	Defines mapping of input records to component attributes.
Output mapping	^{[ 2]}	Defines mapping of results to standard output port.
Error mapping	^{[ 2]}	Defines mapping of errors to error output port.
Redirect error output		If enabled, errors will be sent to the output port instead of the error port.	false (default) \| true
Advanced
Stop processing on fail		By default, a failure causes the component to skip all subsequent command executions and send the information about skipped executions to the error output port. This behaviour can be turned off by this attribute.	true (default) \| false
No lock		By default, MongoDB `eval` command takes a global write lock before evaluating the JavaScript function. As a result, the execution blocks all other read and write operations to the database while the operation runs. Set No lock to `true` to prevent the component from taking the global write lock before evaluating the JavaScript. No lock does not impact whether operations within the JavaScript code itself take a write lock.	false (default) \| true
Field pattern		Specifies the format of placeholders that can be used within the Command attribute. The value of the attribute must contain "`field`" as a substring, e.g. "`<field>`", "`#{field}`", etc. During the execution, each placeholder is replaced using simple string substitution with the value of the respective input field, e.g. the string "`@{name}`" will be replaced with the value of the input field called "`name`" (assuming the default format of the placeholders).	@{field} (default) \| any string containing "`field`" as a substring
^{[ 1]}The attribute is required, unless specified in the Input mapping. ^{[ 2]} Required if the corresponding edge is connected.

Details

Input mapping

Output mapping

Error mapping

MongoDBExecute executes JavaScript code against a MongoDB database connected using the Java driver. Input parameters can be received through the single input port and command results are sent to the first output port. Error information can be sent to the second output port.

The syntax of MongoDBExecute commands is similar to the mongo shell.

The component can be used to perform administrative operations that are not supported by the MongoDBReader or MongoDBWriter, e.g. to drop a collection, create an index, etc.

In general, you shouldn't use MongoDBExecute for reading or writing data to the database, if you can avoid it. Please use the MongoDBReader for reading from the database and the MongoDBWriter for inserting, updating or removing data.

Warning

	Warning
MongoDBExecute internally uses the `eval` command to execute the JavaScript code on the server, which has several limitations and implications: By default, `eval` takes a global write lock before evaluating the JavaScript function. As a result, `eval` blocks all other read and write operations to the database while the operation runs. Set the No lock attribute to `true` to prevent the `eval` command from taking the global write lock before evaluating the JavaScript. No lock does not impact whether operations within the JavaScript code itself take a write lock. Do not use MongoDBExecute for long running operations as the `eval` command blocks all other operations. MongoDBExecute should not be used to retrieve large amounts of data, as there is no streaming support. In particular, transferring long arrays may lead to high memory requirements. You can not use MongoDBExecute with sharded data. In general, you should avoid using `eval` in sharded cluster; nevertheless, it is possible to use it with non-sharded collections and databases stored in a sharded cluster. With authentication enabled, `eval` will fail during the operation if you do not have the permission to perform a specified task. Furthermore, since version 2.4 you must have full admin access (`readWriteAnyDatabase`, `userAdminAnyDatabase`, `dbAdminAnyDatabase` and `clusterAdmin` privileges on the `admin` database) to run the `eval` command.

MongoDBExecute internally uses the eval command to execute the JavaScript code on the server, which has several limitations and implications:

By default, eval takes a global write lock before evaluating the JavaScript function. As a result, eval blocks all other read and write operations to the database while the operation runs. Set the No lock attribute to true to prevent the eval command from taking the global write lock before evaluating the JavaScript. No lock does not impact whether operations within the JavaScript code itself take a write lock.
Do not use MongoDBExecute for long running operations as the eval command blocks all other operations.
MongoDBExecute should not be used to retrieve large amounts of data, as there is no streaming support. In particular, transferring long arrays may lead to high memory requirements.
You can not use MongoDBExecute with sharded data. In general, you should avoid using eval in sharded cluster; nevertheless, it is possible to use it with non-sharded collections and databases stored in a sharded cluster.
With authentication enabled, eval will fail during the operation if you do not have the permission to perform a specified task.
Furthermore, since version 2.4 you must have full admin access (readWriteAnyDatabase, userAdminAnyDatabase, dbAdminAnyDatabase and clusterAdmin privileges on the admin database) to run the eval command.

Editing any of the Input, Output or Error mapping opens the Transform Editor.

Input mapping

The editor allows you to override selected attributes of the component with the values of the input fields.

Field Name	Attribute	Type	Possible values
command	Command	string

Output mapping

The editor allows you to map the results and the input data to the output port.

If output mapping is empty, fields of input record and result record are mapped to output by name.

Field Name	Type	Description
success	boolean	True if the execution has succeeded (can be false when Redirect error output is enabled).
errorMessage	string	If the execution has failed, the field contains the error message (used when Redirect error output is enabled).
stackTrace	string	If the execution has failed, the field contains the stack trace of the error (used when Redirect error output is enabled).
stringResult	string	Conditional. If available, contains the return value of a successful execution serialized to a string.
booleanResult	boolean	Conditional. Contains the return value of a successful execution, if it is a boolean.
integerResult	integer	Conditional. If the return value of the execution is a number, contains its value as an integer.
longResult	long	Conditional. If the return value of the execution is a number, contains its value as a long.
numberResult	number	Conditional. If the return value of the execution is a number, contains its value as a floating point number.
dateResult	date	Conditional. Contains the return value of a successful execution, if it is a date.
stringListResult	string[]	Conditional. If the return value of the execution is iterable, contains the serialized elements as a list.
mapResult	map[string, string]	Conditional. Contains the return value of a successful execution, if it is a map. The values of the map are serialized to strings.
resultType	string	Conditional. Contains the canonical class name of the execution return value, if available.

Error mapping

The editor allows you to map the errors and the input data to the error port.

If error mapping is empty, fields of input record and result record are mapped to output by name.

Field Name	Type	Description
success	boolean	Will always be set to `false`.
errorMessage	string	The error message.
stackTrace	string	The stack trace of the error.

Examples

The following command drops the collection named "orders":

db.orders.drop()

The following snippet creates indices on two fields of the collection named "orders" - "myField1" (ascending order of the keys) and "myField2" (descending order of the keys):

db.orders.createIndex({myField1 : 1});
db.orders.createIndex({myField2 : -1});

The following command returns the names of collections in the database as a list:

db.getCollectionNames()

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MongoDBExecute

Available in Community Designer

Short Description

Icon

Ports

Metadata

MongoDBExecute Attributes

Details

Input mapping

Output mapping

Error mapping

Examples

See also