Not available in Community Designer

Short Description
LDAPReader Attributes
See also

Short Description

LDAPReader reads information from an LDAP directory converting it to CloverETL Data Records.

Component Data source Input ports Output ports Each to all outputs Different to different outputs Transformation Transf. req. Java CTL Auto-propagated metadata
LDAPReaderLDAP directory tree11-n



Port typeNumberRequiredDescriptionMetadata

Input records used for defining base and filter.

If the input port is connected then for each input record one query is assembled and sent to the LDAP server. If such query returns no result then one empty record is sent out (with autofilling fields populated); This behavior requires the input port to be connected.

For correct data records. Results of the search must have the same objectClass. Any [1]
For correct data recordsOutput 0

[1]  Metadata on the output must precisely describe the structure of the read object.


LDAPReader does not propagate metadata.

LDAPReader has no metadata template.

Metadata on the output must precisely describe the structure of the read object. Only Clover fields of types string and byte/compressedByte are supported.

Metadata can use Autofilling Functions. The autofilling attribute filename is set to complete the URL (includes base, filter).

LDAPReader Attributes

AttributeReqDescriptionPossible values
LDAP URLyesLDAP URL of the directory.ldap://host:port/
Base DNyes

Base Distinguished Name (the root of your LDAP tree) used for LDAP search. It is a comma separated list of attribute=value pairs referring to any location with the directory, e.g. if ou=Humans,dc=example,dc=com is the root of the subtree to be searched, entries representing people from example.com domain are to be found.

Optional references to input record's fields in the form $field_name are resolved.


Filter used for the LDAP connection. attribute=value pairs as a filtering condition for the search. All entries matching the filter will be returned, e.g. mail=* returns every entry which has an email address, while objectclass=* is the standard method for returning all entries matching a given base and scope because all entries have values for objectclass.

Optional references to input record's fields in the form $field_name are resolved.


Scope of the search request.

By default, only one object is searched.

If onelevel, the level immediately below the distinguished name is searched.

If subtree, the whole subtree below the distinguished name is searched.

object (default) | onelevel | subtree
UsernoThe user DN to be used when connecting to the LDAP directory. Similar to the following: cn=john.smith,dc=example,dc=com.  
PasswordnoThe password to be used when connecting to the LDAP directory. 
Multi-value separatorno

The character/string to be used when mapping multi-value attribute on simple Clover field as concatenation of string values.

LDAPReader can handle keys with multiple values. These are delimited by this string or character. <none> is special escape value which turns off this functionality, then only the first value is read. This attribute can only be used for string data type. When byte type is used, the first value is the only one that is read.

"|" (default) | other character or string
Alias handling to control how aliases (leaf entries pointing to another object in the namespace) are dereferenced always | never | finding (default)| searching
Referral handling By default, links to other servers are ignored. If follow, the referrals are processed. ignore (default) | follow
Page sizeno The size of the page used in paging. If >0 then LDAP server is queried in paging mode and this attribute defines how many records are returned on one page. e.g. 256
All attributesno The query LDAP for all available attributes or only those directly mappable on output fields. When using defaultField then this should be set to True. True | False
Default fieldno The name of the output field of type MAP(string) where attributes without explicit mapping (corresponding field names on the output port) will be stored. e.g. field15
Binary attributesnoThe list of field names containing binary attributes

By default, the objectGUID is added to the list of binary attributes.

e.g. objectGUID
LDAP Connection PropertiesnoJava Property-like style of key-value definitions which will be added to LDAP connection environment. 


LDAPReader provides the logic to extract the search results and transform them into CloverETL Data Records. The results of the search must have the same objectClass.

The metadata provided on the output port/edge (field names) are used when mapping from LDAP attributes to fields.

Only string and byte (cbyte) Clover data fields are supported. String is compatible with most of LDAP usual types, byte is necessary, for example, for userPassword LDAP type reading.

Multi-value attributes are mapped onto target fields in two ways:

  • if target field is of type List then individual values are stored as individual items.

  • If target field is simple type (and multiValueSeparator is set) then values are concatenated with the defined separator and stored as a single value.

When the defaultMapping field is set (must be of type Map) then all unmapped attributes returned from LDAP server are stored in the map in a key->value manner. Multi-values are stored concatenated.

Alias Handling

Searching the entry to which an alias entry points is known as dereferencing an alias. Setting the Alias handling attribute, you can control the extent to which entries are searched:

  • always: Always dereference aliases.

  • never: Never dereference aliases.

  • finding: Dereference aliases in locating the base of the search but not in searching subordinates of the base.

  • searching: Dereference aliases in searching subordinates of the base but not in locating the base


Reading Data from LDAP
Looking up a Record from LDAP
Reading binary attributes

Reading Data from LDAP

Read records with uid=* from ou=people,dc=foo,dc=? subtree on foobar.com (port 389). Use credentials: user uid=Manager,dc=foo,dc=bar and password manager_password. The values for dc=? will be received from the input edge in the dc field.

LDAP URLldap://example.com:389
Base DNou=people,dc=foo,dc=$dc

Looking up a Record from LDAP

Retrieve information about particular person identified by uid. The uid is received from the input edge. The information about persons is in cn=people,dc=uninett,dc=no subtree on LDAP server example.com (port 389).

The metadata on output port has following fields: cn (string), displayName (string), mail (list of strings), uid (string), objectClass (list of strings), default (map of strings).

LDAP URLldap://example.com:389
Base DNou=people,dc=example,dc=com

The filter parameter contains a reference to the input field name userId. This reference will be resolved for all input records and LDAP query executed (and result parsed) for each input record.

Reading binary attributes

This example shows a way to read binary attributes from LDAP.

Read the records from the Reading Data from LDAP example. In addition to the example, the records contain binary field objectGUID.


The output metadata of LDAPReader should contain a byte field for objectGUID.

Use the Reformat and byte2hex function to convert the byte field to string.


function integer transform() {
 	$out.0.* = $in.0.*;
 	$out.0.logonHours = byte2hex($in.0.logonHours);

 	return ALL;

Similarly, you can use the byte2hex function with a prefix argument to get a hexadecimal string representation of the objectGUID attribute.

String strObjectGUID = byte2hex($in.0.objectGUID,"\\");

Best Practices

  • Improving search performance: If there are no alias entries in the LDAP directory that require dereferencing, choose Alias handling never option.



Since 4-1-0-M1, LDAPReader supports paging.


Since 4.4.1, LDAPReader allows users to read binary data from binary fields. New attributes Binary attributes and LDAP Connection properties are available.

See also

Common Properties of Components
Specific Attribute Types
Common Properties of Readers
Readers Comparison