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Table Hierarchy in ServiceNow: Complete Guide

  • By Aelum consulting
  • April 1, 2021
  • 701 Views

GlideTable Hierarchy is a ServiceNow Server scoped API which provides information about the Table hierarchy and relationships. We have TableUtils API which can be used to retrieve the hierarchy of tables in ServiceNow.

So How actually the Table Hierarchy API is useful?

TableUtils is limited to the global scope in ServiceNow and it cannot be accessed from scoped application. So there is either of ways to achieve this solution:

  1. Copy TableUtils inside the scoped application.
  2. writing logic for GlideRecord the “sys_db_object” table.

This solution implementation might take some additional effort for a developer. So here TableHierarchy API can be very useful to bring our efforts down and easy in implementation. To get the hierarchy of any table in scoped applications. The below methods will be useful.

 Method Summary:

Method Definition
GlideTableHierarchy(String tableName) Instantiates a GlideTableHierarchy object
getName() This method returns the table’s name
getTables() This method returns an array of strings containing table names in the hierarchy
getTableExtensions() This method returns an array containing the table names that extend the current table
getAllExtensions() This method returns an array containing the table names that extend the current table and includes the current table
getHierarchy() This method returns an array of all classes in the hierarchy of the current table
getRoot() This method returns the top-level class in the hierarchy
getBase() This method returns the parent class
isBaseClass() This method returns a boolean value, true if this is the base class 
isSoloClass() This method returns a boolean value, true if this is not part of any hierarchy
hasExtensions() This method returns a boolean value, true if the table has any child classes

In this Blog, We will drive through a few methods of this API with reference to the CMDB table hierarchy. For that we can use this API as follows:

API Definition: getTableExtensions() returns an array containing the table names that extend the current table.

Note: Current table will not be part of the return object. If you want to include the current table in the return object use getAllExtensions() method.

To fetch all the child tables(hierarchy) for the cmdb_ci_computer  table. We can use this method as explained below in the example.

Scoped Global
var hierarchy=new GlideTableHierarchy (‘cmdb_ci_computer’);var tables=hierarchy.getTableExtensions();gs.info(tables); var hierarchy= new TableUtils (“cmdb_ci_computer”);var tables=hierarchy.getTableExtensions();gs.info(tables);

 Output:

cmdb_ci_ucs_blade, cmdb_ci_server, cmdb_ci_osx_server, cmdb_ci_mainframe, cmdb_ci_datapower_server, cmdb_ci_lb, cmdb_ci_lb_bigip, cmdb_ci_lb_a10, cmdb_ci_lb_cisco_csm, cmdb_ci_lb_alteon, cmdb_ci_lb_f5_gtm, cmdb_ci_lb_cisco_gss, cmdb_ci_lb_isa, cmdb_ci_lb_cisco_css, cmdb_ci_lb_ace, cmdb_ci_lb_radware, cmdb_ci_lb_network, cmdb_ci_lb_netscaler, cmdb_ci_lb_f5_ltm, cmdb_ci_ibm_zos_server, cmdb_ci_virtualization_server, cmdb_ci_vcenter_server_obj, cmdb_ci_esx_server, cmdb_ci_hyper_v_server, cmdb_ci_storage_server, cmdb_ci_win_server, cmdb_ci_linux_server, cmdb_ci_storage_node_element, cmdb_ci_isam_server, cmdb_ci_mainframe_lpar, cmdb_ci_server_hardware, cmdb_ci_tape_server, cmdb_ci_net_app_server, cmdb_ci_chassis_server, cmdb_ci_netware_server, cmdb_ci_unix_server, cmdb_ci_aix_server, cmdb_ci_solaris_server, cmdb_ci_hpux_server, cmdb_ci_cim_server, cmdb_ci_storage_switch, cmdb_ci_mainframe_hardware, cmdb_ci_pc_hardware, cmdb_ci_ucs_rack_uniAPI Definition: getHierarchy() returns an array of all classes in the hierarchy of the current table.

Scoped Global
var hierarchy=new GlideTableHierarchy(‘cmdb_ci_computer’);var tables=hierarchy.getHierarchy();gs.info(tables); var hierarchy= new TableUtils(“cmdb_ci_computer”);var tables=hierarchy.getHierarchy();gs.log(tables);

 Output:

cmdb_ci_computer, cmdb_ci_hardware, cmdb_ci, cmdb, cmdb_ci_ucs_blade, cmdb_ci_server, cmdb_ci_osx_server, cmdb_ci_mainframe, cmdb_ci_datapower_server, cmdb_ci_lb, cmdb_ci_lb_bigip, cmdb_ci_lb_a10, cmdb_ci_lb_cisco_csm, cmdb_ci_lb_alteon, cmdb_ci_lb_f5_gtm, cmdb_ci_lb_cisco_gss, cmdb_ci_lb_isa, cmdb_ci_lb_cisco_css, cmdb_ci_lb_ace, cmdb_ci_lb_radware, cmdb_ci_lb_network, cmdb_ci_lb_netscaler, cmdb_ci_lb_f5_ltm, cmdb_ci_ibm_zos_server, cmdb_ci_virtualization_server, cmdb_ci_vcenter_server_obj, cmdb_ci_esx_server, cmdb_ci_hyper_v_server, cmdb_ci_storage_server, cmdb_ci_win_server, cmdb_ci_linux_server, cmdb_ci_storage_node_element, cmdb_ci_isam_server, cmdb_ci_mainframe_lpar, cmdb_ci_server_hardware, cmdb_ci_tape_server, cmdb_ci_net_app_server, cmdb_ci_chassis_server, cmdb_ci_netware_server, cmdb_ci_unix_server, cmdb_ci_aix_server, cmdb_ci_solaris_server, cmdb_ci_hpux_server, cmdb_ci_cim_server, cmdb_ci_storage_switch, cmdb_ci_mainframe_hardware, cmdb_ci_pc_hardware, cmdb_ci_ucs_rack_unit

API Definition: getRoot() returns the top-level class in the hierarchy.

For Global, a Similar method is getAbsoluteBase() which returns the base table name from which the table was extended.

Note: For any table under the cmdb_ci hierarchy, this method returns cmdb_ci and not CMDB, which is the actual base table.

 

Scoped Global
var hierarchy=new GlideTableHierarchy(‘cmdb_ci_computer’);var tables=hierarchy.getRoot();gs.info(tables); No similar Method available

 

Output:

cmdb

API Definition: getBase() returns the parent class which current class is extending like task(return) for incident(argument).

 

Scoped Global
var hierarchy=new GlideTableHierarchy(‘cmdb_ci_computer’);var tables=hierarchy.getBase();gs.info(tables); No similar Method available

 

Output:

Cmdb_ci_hardware

Thanks You for Readings

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