tMongoDBInput

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tMongoDBInput Properties

Component family	Big Data / MongoDB
Function	tMongoDBInput retrieves certain documents from a MongoDB database collection by supplying a query document containing the fields the desired documents should match.
Purpose	This component allows you to retrieve records from a collection in the MongoDB database and transfer them to the following component for display or storage.
Basic settings	Use existing connection	Select this check box and in the Component List click the relevant connection component to reuse the connection details you already defined.
	DB Version	List of the database versions. Available when the Use existing connection check box is not selected.
	Use replica set address	Select this check box to show the Replica address table. In the Replica address table, you can define multiple MongoDB database servers for failover. Available when the Use existing connection check box is not selected.
	Server and Port	IP address and listening port of the database server. Available when the Use existing connection or Use replica set address check box is not selected.
	Database	Name of the database.
	Use SSL connection	Select this check box to enable the SSL encrypted connection. Then you need to use the tSetKeystore component in the same Job to specify the authentication information. For further information about tSetKeystore, see tSetKeystore. 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 you want the Job to read from the MongoDB replica set to be used. If you leave this check box clear, the Job reads the default member of the replica set. For further information, see MongoDB’s documentation about Replication and its Read preferences.
	Required authentication	Select this check box to enable the database authentication.
	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.
	Collection	Name of the collection in the MongoDB database.
	Schema and Edit Schema	A schema is a row description. It defines the number of fields to be processed and passed on to the next component. The schema is either Built-In or stored remotely in the Repository. Click Edit schema to make changes to the schema. If the current schema is of the Repository type, three options are available: View schema: choose this option to view the schema only. Change to built-in property: choose this option to change the schema to Built-in for local changes. Update repository connection: choose this option to change the schema stored in the repository and decide whether to propagate the changes to all the Jobs upon completion. If you just want to propagate the changes to the current Job, you can select No upon completion and choose this schema metadata again in the [Repository Content] window.
	Query	Specify the query condition. For example, type in `"{id:4}"` to retrieve the record whose id is 4 from the collection specified in the Collection field. Note Different from the query statements required in the MongoDB client software, the query here refers to the contents inside `find()`, such as the query here `{id:4}` versus the MongoDB client query `db.blog.find({id:4})`.
	Mapping	Specify the parent node for the column in the MongoDB database.
	Sort by	Specify the column and choose the order for the sort operation.
	Limit	Type in the maximum number of records to be retrieved.
Advanced settings	tStatCatcher Statistics	Select this check box to collect the log data at the component level.
Global Variables	NB_LINE: the number of rows read by an input component or transferred to an output component. 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. 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	As a start component, tMongoDBInput allows you to retrieve records from a collection in the MongoDB database and transfer them to the following component for display or storage.
Log4j	The activity of this component can be logged using the log4j feature. For more information on this feature, see Talend Studio User Guide. For more information on the log4j logging levels, see the Apache documentation at http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/Level.html.

Scenario: Retrieving data from a collection by advanced queries

In this scenario, advanced MongoDB queries are used to retrieve the post by the author
Anderson.

There are such posts in the collection blog of the
MongoDB database talend:

To insert data into the database, see Scenario 1: Creating a collection and writing data to it.

Linking the components

Drop tMongoDBConnection, tMongoDBClose, tMongoDBInput and tLogRow
onto the workspace.
Link tMongoDBConnection to tMongoDBInput using the OnSubjobOk trigger.
Link tMongoDBInput to tMongoDBClose using the OnSubjobOk trigger.
Link tMongoDBInput to tLogRow using a Row > Main
connection.

Configuring the components

Double-click tMongoDBConnection to open
its Basic settings view.
From the DB Version list, select the
MongoDB version you are using.
In the Server and Port fields, enter the connection details.
In the Database field, enter the name of the MongoDB
database.
Double-click tMongoDBInput to open its
Basic settings view.
Select the Use existing connection
option.
In the Collection field, enter the name
of the collection, namely blog.
Click the […] button next to Edit schema to open the schema editor.
Click the [+] button to add five columns,
namely id, author, title, keywords and contents, with the type as Integer and String
respectively.
Click OK to close the editor.
The columns now appear in the left part of the Mapping area.
For columns author, title, keywords and contents,
enter their parent node post so that the
data can be retrieved from the correct positions.
In the Query box, enter the advanced
query statement to retrieve the posts whose author is Anderson:

"{post.author : 'Anderson'}"

1

"{post.author : 'Anderson'}"

This statement requires that the sub-node of post, the node author,
should have the value “Anderson”.
Double-click tLogRow to open its
Basic settings view.

Select Table (print values in cells of a
table) for a better display of the results.

Executing the Job

Press Ctrl+S to save the Job.
Press F6 to run the Job.

As shown above, the post by Anderson is retrieved.

Related scenarios

For related scenarios, see:

Document get from Talend https://help.talend.com

Thank you for watching.

Docs 5.x

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tMongoDBInput – Docs for ESB 5.x