Property type

Either Built-In or Repository.

Built-In: No property data stored centrally.

Repository: Select the repository file where the
properties are stored.

Use an existing connection

Select this check box and in the Component List click the relevant connection component to
reuse the connection details you already defined.

Note that when a Job contains the parent Job and the child Job,
Component List presents only the
connection components in the same Job level.

Use replica set address or multiple query routers

Select this check box to show the Server
addresses table.

In the Server addresses table, define the sharded
MongoDB databases or the MongoDB replica sets you want to connect
to.

Server and Port

IP address and listening port of the database server.

Available when the Use replica set
address check box is not selected.

Note that if you use the authentication mechanisms to connect to this MongoDB
database, you must enter the name, rather than the IP address, of the host of the database
server.

Database

Name of the database.

Use SSL connection

Select this check box to enable the SSL or TLS encrypted connection.

Then you need to use the tSetKeystore
component in the same Job to specify the encryption information.

Note that the SSL connection is available only for the version 2.4 + of
MongoDB.

Set read preference

Select this check box and from the Read preference
drop-down list that is displayed, select the member to which you need to direct the read
operations.

If you leave this check box clear, the Job uses the default Read preference, that is to
say, uses the primary member in a replica set.

For further information, see MongoDB’s documentation about Replication and its Read
preferences.

Use authentication

Select this check box to enable the database authentication.

Among the mechanisms listed on the Authentication mechanism
drop-down list, the NEGOTIATE one is recommended if
you are not using Kerberos, because it automatically select the authentication mechanism
the most adapted to the MongoDB version you are using.

For details about the other mechanisms in this list, see MongoDB Authentication from the MongoDB
documentation.

Set Authentication database

If the username to be used to connect to MongoDB has been created in a specific
Authentication database of MongoDB, select this check box to enter the name of this
Authentication database in the Authentication database
field that is displayed.

For further information about the MongoDB Authentication database, see User Authentication database.

Username and Password

DB user authentication data.

To enter the password, click the […] button next to the
password field, and then in the pop-up dialog box enter the password between double quotes
and click OK to save the settings.

Available when the Required
authentication check box is selected.

If the security system you have selected from the Authentication mechanism drop-down list is Kerberos, you need to
enter the User principal, the Realm and the KDC
server fields instead of the Username and the Password
fields.

Bucket

Enter the name of the bucket in which the files to be listed are
stored. A bucket of GridFS is similar to a folder.

Query

Enter the query to be used to select the files to be listed. You need
to define how these files are sorted in the list by selecting:

• Sort by: these files can be
  sorted by their filename
  attributes, uploadDate
  attributes or length (the
  File Size option)
  attributes.

• Sort order: these files can
  be sorted in the Ascending or
  Descending order.

tStatCatcher Statistics

Select this check box to collect the log data at the component
level.

No query timeout

Select this check box to prevent MongoDB servers from stopping idle
cursors at the end of 10-minute inactivity of these cursors. In this
situation, an idle cursor will stay open until either the results of
this cursor are exhausted or you manually close it using the
cursor.close() method.

A cursor for MongoDB is a pointer to the result set of a query. By
default, that is to say, with this check box being clear, a MongoDB
server automatically stops idle cursors after a given inactivity period
to avoid excess memory use. For further information about MongoDB
cursors, see https://docs.mongodb.org/manual/core/cursors/.

Global Variables

NB_FILE: the number of files processed. This is an After
variable and it returns an integer.

ERROR_MESSAGE: the error message generated by the
component when an error occurs. This is an After variable and it returns a string. This
variable functions only if the Die on error check box is
cleared, if the component has this check box.

CURRENT_FILEID: the value of the ObjectId (the file ID) attribute of the current file. This is an Flow
variable and it returns a string.

CURRENT_FILENAME: the value of the filename attribute of the current file. This is an Flow
variable and it returns a string.

CURRENT_FILEUPLOADDATE: the value of the uploadDate attribute of the current file. This is an Flow
variable and it returns a date.

CURRENT_FILELENGTH: the value of the length (the size) attribute of the current file. This is an
Flow variable and it returns a length.

CURRENT_FILEMD5: the value of the md5 attribute of the current file. This is an Flow variable and it returns a
string.

A Flow variable functions during the execution of a component while an After variable
functions after the execution of the component.

To fill up a field or expression with a variable, press Ctrl +
Space to access the variable list and choose the variable to use from it.

For further information about variables, see
Talend Studio

User Guide.

Usage rule

This component combines MongoDB GridFS connection and data iteration, thus usually used
as a single-component subJob to list files stored in a given bucket in
MongoDB GridFS.

Different lists are returned, each representing an attribute of these
files and being stored in a specific global variable as explained above
regarding the global variables provided by tMongoDBGridFSList.

It is often connected to the Job using OnSubjobOk or OnComponentOk link, depending on the context.