---
sourceDocument: Xanadu API Reference
sourceDocumentLink: https://servicenow-prod.fluidtopics.net/r/xanadu/api-reference

 Release :

    - xanadu

ft:locale :

    - en-US

ft:publication_title :

    - Xanadu API Reference

ft:clusterId :

    - crapiref

bundleId :

    - crapiref

workflow :

    - Creator


---

# HistoryWalker - Scoped, Global

# HistoryWalker - Scoped, Global {#ariaid-title1}

* Release version: Xanadu
* 
* Updated August 1, 2024
* 
* ![](https://www.servicenow.com/docs/portal-asset/ico-clock) 17 minutes to read

The HistoryWalker API uses the audit/history tables to generate a historical version of an existing record. This historical version contains all updates to all fields for the specified glide
record.

This API provides the ability to return a GlideRecord to a previous update count (walked GlideRecord) with the appropriate glide elements populated. After the walked GlideRecord is retrieved, the API provides the ability to move
forward and backward between the update numbers, navigating through its historical updates.

This API enables you to:

* Instruct the HistoryWalker API to use a specific history walker implementation to retrieve audit data.
* Navigate through the historical version of a glide record.
* Apply the appropriate history/audit data to get an existing GlideRecord to the state it was in a specific update count.
* Turn off row-level access control.
* Turn off field-level access control.
* Turn off retrieval and processing of "changes" data.
* Enable journal fields.
* Enable variables.

The HistoryWalker API provides four ways to retrieve audit data:

1. HISTORY - History walkerIf not available or not up to date, creates a History Set \[sys_history_set\] record for the glide record that you passed when instantiating the HistoryWalker API, using the data in the
   Sys Audit \[sys_audit\] table. The sys_history_set table contains the name of the associated History \[sys_history_line\] table. The sys_history_line table contains a record for each field value that has been updated in the table
   being walked. Using this retrieval method, HistoryWalker methods retrieve history data from the generated sys_history_line table, instead of directly querying the sys_audit table.

   The records within the sys_history_line table are sorted and grouped by ascending Update \[update\] field values rather than by chronological order. The update field is loosely associated with the Updates \[sys_mod_count\] field on the task table.  
   Note:  
   Updates of the sys_mod_count by clients is not synchronized and therefore can be overwritten, making this count unreliable.
2. AUDIT - Audit walkerQueries the sys_audit table for the glide record that you passed when instantiating the HistoryWalker API. Each record in the sys_audit table contains the changes to field values that
   occurred through the life of the record.

   Records are sorted ascending by the Update count \[record_checkpoint\] field rather than by chronological order. The record_checkpoint field is loosely associated with the Updates
   \[sys_mod_count\] field on the task table. One-to-one correlation is not guaranteed.  
   Things to consider when deciding whether to use the AUDIT retrieval method:
   * Size of the sys_audit table. The sys_audit table can become quite large as the changes for all fields in all records are maintained in this table.
   * Possible lack of update zero record depending on the setting of the system property glide.sys.audit_inserts. This property defines whether an audit record is created with the initial field values when a record is first inserted in a table. In a base system, this property is set to "false" causing the HistoryWalker API to do additional processing to account for this missing information.

   As such, running the HistoryWalker API with AUDIT isn't as performant as either HISTORY or CHECKPOINT.
3. CHECKPOINT - Checkpoint walkerUses a hybrid approach to obtain historical data from the sys_history_set or sys_audit table depending on the setting of the system property
   com.glide.history_walker.max_history_count. If the record to walk has a sys_mod_count that exceeds the value set in this property, default value = 1,000, the checkpoint walker uses the sys_audit table to
   obtain history data. Otherwise it uses the sys_history_set table.

   The reason for this check is that the sys_history_set table provides a more performant approach for walking history data, but only up to a certain point. When
   the total number of field updates reaches a certain level, approximately 10K, the generation of the sys_history_set table can exceed the user transaction timeout. If the timeout is exceeded, the overall results are worse in
   performance than running against the sys_audit table that contains all table updates. The checkpoint walker uses the com.glide.history_walker.max_history_count to determine the optimal record set to use to
   achieve the best performance.

   Records are grouped and sorted ascending by the Record Internal Checkpoint \[internal_checkpoint\] field. Since the internal_checkpoint field is a timestamp, the records are in chronological
   order. In addition, the internal_checkpoint field has no association to the task.sys_mod_count field.

   The most important difference between the checkpoint walker and other walkers is that the other walkers are coupled to and
   driven by task.sys_mod_count entries and related to sys_audit.record_checkpoint and sys_history_line.update. The checkpoint walker uses the sys_audit.internal_checkpoint and sys_history_line.internal_checkpoint fields
   respectively.

   The record internal checkpoint addresses both of these issues making the checkpoint walker the most reliable way to retrieve audit history data.
4. OFFLINE - Offline history walkerProvides the offline history feature used by applications such as the Field Service mobile offline app. When a task table extension has fields with the dictionary attribute
   offline_timestamp_field set, the offline history walker runs irrespective of any property or explicit instruction to use another walker. The offline history walker uses the sys_history_line and sys_history_set tables, which
   contain history data purposely ordered by date and time, to support offline updates. Only the offline history walker can give accurate results for such tables.

   Note:  
   For offline updates, the HistoryWalker API is initiated automatically and the only two methods that you can use are: walkTo(0) and walkForward(). You can't call other HistoryWalker methods for offline updates.

The system property com.snc.walker.default defines the default type of record walking to perform when instantiating the HistoryWalker API. For upgrading customers, this property is set to
"HISTORY". For new customers, this property is set to "CHECKPOINT".  
When you instantiate the HistoryWalker API as follows, the com.snc.walker.default property determines which record walker implementation the API uses.

    var hw = new sn_hw.HistoryWalker(<table name>, <sys_id>);

You can also pass the type of record walker to use when instantiating the API. It's advisable to always include the desired walker implementation when instantiating this API.

    var hw = new sn_hw.HistoryWalker(<table name>, <sys_id>, <walker>);

such as:

    var hw = new sn_hw.HistoryWalker('incident', '1c741bd70b2322007518478d83673af3', 'CHECKPOINT');

To use this class in scoped and global applications, use the `sn_hw` namespace identifier. The History Walker plugin (com.glide.history_walker) that is enabled by default is required to access the
HistoryWalker API.

## HistoryWalker - HistoryWalker(String tableName, String sysId, String walker) {#ariaid-title2}

Instantiates the HistoryWalker object and retrieves the historic data for the specified glide record.
{#HW-HistoryWalker_S_S__table_sdw_1tl_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| tableName | String | Name of table that contains the record to retrieve. |
| sysId | String | Sys_id of the record whose historic data you want to retrieve. |
| walker | String | Optional. Name of the history walker to use to retrieve the historic data for the specified record. Valid values: * AUDIT * CHECKPOINT * HISTORY * OFFLINE Default: Walker specified in the system property com.snc.walker.default. |
[Table 1. Parameters]

{#HW-HistoryWalker_S_S__table_sdw_1tl_qbb}  
The following code example shows how to call this method to walk through the changes made to the GlideRecord using the checkpoint walker.


    var gr_Hw = new GlideRecord('sc_req_item');
    gr_Hw.get('b0d3335d49534210f877468e89703a7c');
     
    var hw = new sn_hw.HistoryWalker(gr_Hw.getTableName(), gr_Hw.getUniqueValue(), 'CHECKPOINT');
    hw.walkTo('19096afcc800000001');
    printChangedFields(hw);
     
    function printChangedFields(hw) {
       var walkedGr = hw.getWalkedRecord();
       var fields = GlideScriptRecordUtil.get(walkedGr).getChangedFieldNames();
       gs.info('Fields changed at update ' + hw.getUpdateNumber() + ' were:');
       for (var j = 0; j < fields.size(); j++) {
          var fieldName = fields.get(j) + '';
          if (fieldName !== 'variables')
             gs.info(walkedGr.getValue('sys_updated_on') + ' ' + fieldName + '=' + walkedGr.getValue(fieldName));
       }
     
       var variables = walkedGr.variables;
       for (var variableName in variables) {
          if (variables[variableName].changes())
             gs.info(walkedGr.getValue('sys_updated_on') + ' ' + variableName + '=' + variables[variableName].getValue());
       }
       gs.info('');
    }

Output:

    Fields changed at update 3 were:
    2024-07-09 08:50:21 price=1499
    2024-07-09 08:50:21 state=2
    2024-07-09 08:50:21 priority=2
    2024-07-09 08:50:21 recurring_price=100

## HistoryWalker - HistoryWalker(String tableName, String sysId, Boolean useAudit) {#ariaid-title3}

Fetches the database record based on the parameters, using the History Sets or Audit
data to retrieve the historic data, depending on the third parameter.
{#HW-HistoryWalker_S_S_B__table_h5d_ycn_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| tableName | String | Name of table containing the record to retrieve. |
| sysId | String | Sys_id of the record to retrieve. |
| useAudit | Boolean | Flag that indicates whether to use audit data to retrieve historic date. Valid values: * true: Use audit data to retrieve historic date. * false: Use history set to retrieve historic date. |
[Table 2. Parameters]

{#HW-HistoryWalker_S_S_B__table_h5d_ycn_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');

    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue(), true);
    if (hw.walkTo(3)) {
        var oldPriority = hw.getWalkedRecord().priority;
        gs.info('Incident priority in update number ' + hw.getUpdateNumber() + ' was ' + oldPriority);
    } else
        gs.info('Incident does not have update number 3');

Output:

    Incident priority in update number 3 was 4

## HistoryWalker - getUpdateNumber() {#ariaid-title4}

Gets the update number of the current walked glide record.
{#HW-getUpdateNumber__table_chz_2bt_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| None |   |   |
[Table 3. Parameters]

{#HW-getUpdateNumber__table_chz_2bt_qbb} {#HW-getUpdateNumber__table_dhz_2bt_qbb__entry__2}

| Type | Description |
|-|-|
| int | Current update number or -1 if record is not found. |
[Table 4. Returns]

{#HW-getUpdateNumber__table_dhz_2bt_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');

    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    for(int i = 0; i < 2; i++) {
      hw.walkForward();
    }
    gs.info('Update number: ' + hw.getUpdateNumber());

Output:

    Update number: 3

## HistoryWalker - getWalkedRecord() {#ariaid-title5}

Gets the record filled with the history/audit data after walking to an update
number.
{#HW-getWalkedRecord__table_sbt_f1t_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| None |   |   |
[Table 5. Parameters]

{#HW-getWalkedRecord__table_sbt_f1t_qbb} {#HW-getWalkedRecord__table_tbt_f1t_qbb__entry__2}

| Type | Description |
|-|-|
| GlideRecord | The walked GlideRecord. |
[Table 6. Returns]

{#HW-getWalkedRecord__table_tbt_f1t_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');
     
    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    hw.walkForward();
    var walkedRecord = hw.getWalkedRecord();
    gs.info('Priority in update number 0: ' + walkedRecord.priority);
    hw.walkForward();
    walkedRecord = hw.getWalkedRecord();
    gs.info('Short description in update number 1: ' + walkedRecord.short_description);

Output:

     Priority in update number 0: 4
    Short description in update number 1: My monitor has stopped working

## HistoryWalker - getWalkedRecordCopy() {#ariaid-title6}

Returns a copy of the record filled with the history/audit data after walking to an
update number.
Note:  
The getWalkedRecord() method might modify the obtained walkedRecord after walking to another update number. The getWalkedRecordCopy() method gets a clone to the walked record to prevent that.
{#HW-getWalkedRecordCopy__table_qpk_t1t_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| None |   |   |
[Table 7. Parameters]

{#HW-getWalkedRecordCopy__table_qpk_t1t_qbb} {#HW-getWalkedRecordCopy__table_rpk_t1t_qbb__entry__2}

| Type | Description |
|-|-|
| GlideRecord | Copy of the walked GlideRecord. |
[Table 8. Returns]

{#HW-getWalkedRecordCopy__table_rpk_t1t_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');
     
    var walkedRecord = [];
    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    hw.walkForward();
    walkedRecord[0] = hw.getWalkedRecordCopy();
    hw.walkForward();
    walkedRecord[1] = hw.getWalkedRecordCopy();
     
    gs.info('Priority in update number 0: ' + walkedRecord[0].priority);
    gs.info('Short description in update number 1: ' + walkedRecord[1].short_description);

Output:

    Priority in update number 0: 4
    Short description in update number 1: My monitor has stopped working

## HistoryWalker - isFieldLevelSecurity() {#ariaid-title7}

Specifies if the record-level read access is applied on the record when retrieving from
the database.
{#HW-isFieldLevelSecurity__table_xcy_1vs_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| None |   |   |
[Table 9. Parameters]

{#HW-isFieldLevelSecurity__table_xcy_1vs_qbb} {#HW-isFieldLevelSecurity__table_ycy_1vs_qbb__entry__2}

| Type | Description |
|-|-|
| Boolean | Flag that indicates whether field-level security is enabled. Valid values: * true: Field-level security is enabled. * false: Field-level security isn't enabled. |
[Table 10. Returns]

{#HW-isFieldLevelSecurity__table_ycy_1vs_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');

    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    gs.info('Field level security is active: ' + hw.isFieldLevelSecurity());

Output:

    Field level security is active: true

## HistoryWalker - isRecordLevelSecurity() {#ariaid-title8}

Specifies if the record-level read access is applied on the record when retrieving from
the database.
{#HW-isRecordLevelSecurity__table_orv_jts_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| None |   |   |
[Table 11. Parameters]

{#HW-isRecordLevelSecurity__table_orv_jts_qbb} {#HW-isRecordLevelSecurity__table_prv_jts_qbb__entry__2}

| Type | Description |
|-|-|
| Boolean | Flag that indicates whether record-level security is enabled. Valid values: * true: Record-level security is enabled. * false: Record-level security isn't enabled. |
[Table 12. Returns]

{#HW-isRecordLevelSecurity__table_prv_jts_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');

    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    gs.info('Record level security is active: ' + hw.isRecordLevelSecurity());

Output:

    Record level security is active: true

## HistoryWalker - isWithChanges() {#ariaid-title9}

Specifies if any of the methods that walk the record from one update to another,
support the "changes" data for each element.
{#HW-isWithChanges__table_ys5_nrs_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| None |   |   |
[Table 13. Parameters]

{#HW-isWithChanges__table_ys5_nrs_qbb} {#HW-isWithChanges__table_zs5_nrs_qbb__entry__2}

| Type | Description |
|-|-|
| Boolean | Flag that indicates whether change support is enabled. Valid values: * true: Change support is enabled. * false: Change support isn't enabled. {#HW-isWithChanges__ul_qbs_vzl_5bc} |
[Table 14. Returns]

{#HW-isWithChanges__table_zs5_nrs_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');

    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    gs.info('Changes is active: ' + hw.isWithChanges());

Output:

    Changes is active: true

## HistoryWalker - isWithJournalFields() {#ariaid-title10}

Specifies if journal type fields are populated from the historical values.
{#HW-isWithJournalFields__table_rmd_1ws_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| None |   |   |
[Table 15. Parameters]

{#HW-isWithJournalFields__table_rmd_1ws_qbb} {#HW-isWithJournalFields__table_smd_1ws_qbb__entry__2}

| Type | Description |
|-|-|
| Boolean | Flag that indicates whether journal fields are populated. Valid values: * true: Journal fields are populated. * false: Journal fields aren't populated. |
[Table 16. Returns]

{#HW-isWithJournalFields__table_smd_1ws_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');

    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    gs.info('Populating journal fields is active: ' + hw. isWithJournalFields());

Output:

    Populating journal fields is active: false

## HistoryWalker - isWithVariables() {#ariaid-title11}

Specifies if values are set for variables that are recorded in the history.
{#HW-isWithVariables__table_phm_jxs_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| None |   |   |
[Table 17. Parameters]

{#HW-isWithVariables__table_phm_jxs_qbb} {#HW-isWithVariables__table_qhm_jxs_qbb__entry__2}

| Type | Description |
|-|-|
| Boolean | Flag that indicates whether values are set for variables that are recorded in the history. Valid values: * true: Values are set. * false: Values aren't set. {#HW-isWithVariables__ul_rpj_y1m_5bc} |
[Table 18. Returns]

{#HW-isWithVariables__table_qhm_jxs_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');

    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    gs.info('Populating variables is active: ' + hw. isWithVariables());

Output:

    Populating variables is active: false

## HistoryWalker - setFieldLevelSecurity(Boolean fieldLevelSecurity) {#ariaid-title12}

Sets the field-level read access on each element before setting the historical value of that element in the GlideRecord. If the field-level security is enabled, it prevents the API from populating the fields of the walked
record that the user of the API doesn't have access to.
{#HW-setFieldLevelSecurity_B__table_clj_xts_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| fieldLevelSecurity | Boolean | Flag that indicates how to set the field-level read access security. Valid values: * true: Enable field-level security. * false: Disable field-level security. Default: true |
[Table 19. Parameters]

{#HW-setFieldLevelSecurity_B__table_clj_xts_qbb} {#HW-setFieldLevelSecurity_B__table_dlj_xts_qbb__entry__2}

| Type | Description |
|-|-|
| void |   |
[Table 20. Returns]

{#HW-setFieldLevelSecurity_B__table_dlj_xts_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');
     
    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    hw.setFieldLevelSecurity(false);
    hw.walkForward();

## HistoryWalker - setRecordLevelSecurity(Boolean recordLevelSecurity) {#ariaid-title13}

Sets the record-level read access on the record when retrieving from the database. The record-level security prevents the API from retrieving the walked record if the user of the API doesn't have access to the
GlideRecord.
{#HW-setRecordLevelSecurity_B__table_trq_kss_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| recordLevelSecurity | Boolean | Flag that indicates how to set the record-level read access security. Valid values: * true: Enable record-level security. * false: Disable record-level security. Default: true |
[Table 21. Parameters]

{#HW-setRecordLevelSecurity_B__table_trq_kss_qbb} {#HW-setRecordLevelSecurity_B__table_urq_kss_qbb__entry__2}

| Type | Description |
|-|-|
| void |   |
[Table 22. Returns]

{#HW-setRecordLevelSecurity_B__table_urq_kss_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');

    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    hw.setRecordLevelSecurity(false);
    hw.walkForward();

## HistoryWalker - setWithChanges(Boolean withChanges) {#ariaid-title14}

Sets the "changes" data support for each element for a method that walks the record
from one update to another.
{#HW-setWithChanges_B__table_ob3_c2n_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| withChanges | Boolean | Flag that indicates whether the changes data is supported for each element. Valid values: * true: Change data is supported for each element. * false: Change data is not supported for each element. Default: true |
[Table 23. Parameters]

{#HW-setWithChanges_B__table_ob3_c2n_qbb} {#HW-setWithChanges_B__table_pb3_c2n_qbb__entry__2}

| Type | Description |
|-|-|
| void |   |
[Table 24. Returns]

{#HW-setWithChanges_B__table_pb3_c2n_qbb}  
This code example shows how to call this method with Changes data support. This example must be run in global scope.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');
    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    while (hw.walkForward()) {
      printChangedFields(hw);
    }

    function printChangedFields(hw) {
      var walkedGr = hw.getWalkedRecord();
      var fields = GlideScriptRecordUtil.get(walkedGr).getChangedFieldNames();
      gs.info("Fields changed at update " + hw.getUpdateNumber() + " were:");
      for (var j = 0; j < fields.size(); j++)
        gs.info(" " + fields.get(j));
      gs.info("");
    }

This code example shows how to call this method without Changes data support. This example runs in both scoped and global environments.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');
    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    hw.setWithChanges(false);

    while (hw.walkForward()) {
      var oldPriority = hw.getWalkedRecord().priority;
      gs.info('Incident priority in update number ' + hw.getUpdateNumber() + ' was ' + oldPriority);
    }

## HistoryWalker - setWithJournalFields(Boolean withJournalFields) {#ariaid-title15}

Specifies if journal type fields are populated from the historical values.
{#HW-setWithJournalFields_B__table_nz1_nvs_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| withJournalFields | Boolean | Flag that indicates whether to include journal-type fields. Valid values: * true: Include journal-type fields. * false: Don't include journal-type fields. Default: false |
[Table 25. Parameters]

{#HW-setWithJournalFields_B__table_nz1_nvs_qbb} {#HW-setWithJournalFields_B__table_oz1_nvs_qbb__entry__2}

| Type | Description |
|-|-|
| void |   |
[Table 26. Returns]

{#HW-setWithJournalFields_B__table_oz1_nvs_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');
    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    hw.setWithJournalFields(true);
    if (hw.walkForward()) {
      var workNotes = hw.getWalkedRecord().work_notes;
      gs.info('Work Notes in update number ' + hw.getUpdateNumber() + ' was ' + workNotes);
    }

## HistoryWalker - setWithVariables(Boolean withVariables) {#ariaid-title16}

Specifies if variables are populated from the historical values.
{#HW-setWithVariables_B__table_v4q_rws_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| withVariables | Boolean | Flag that indicates whether variables are populated from the historical values. Valid values: * true: Variable are populated. * false: Variable aren't populated. Default: false |
[Table 27. Parameters]

{#HW-setWithVariables_B__table_v4q_rws_qbb} {#HW-setWithVariables_B__table_w4q_rws_qbb__entry__2}

| Type | Description |
|-|-|
| void |   |
[Table 28. Returns]

{#HW-setWithVariables_B__table_w4q_rws_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');

    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    hw.setWithVariables(true);
    hw.walkTo(0);
    if (hw.walkTo(0)) {
        var varUrgency = hw.getWalkedRecord().variables.urgency;
        gs.info('Variable Urgency in update number ' + hw.getUpdateNumber() + ' was ' + varUrgency);
    }

## HistoryWalker - walkBackward() {#ariaid-title17}

Applies the appropriate history/audit data to get a walked GlideRecord to the state
when it was one update number backward. If the previous update count is missing from the
history/audit data, it will walk to the previous available update count.
{#HW-walkBackward__table_rc3_nzs_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| None |   |   |
[Table 29. Parameters]

{#HW-walkBackward__table_rc3_nzs_qbb} {#HW-walkBackward__table_sc3_nzs_qbb__entry__2}

| Type | Description |
|-|-|
| Boolean | Flag that indicates whether walking to the specified update number was possible. Valid values: * true: Able to walk to the specified update number. * false: Unable to walk to the specified update number. Possible reasons: Already walked to the update number 0. |
[Table 30. Returns]

{#HW-walkBackward__table_sc3_nzs_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');
    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());

    while (hw.walkBackward()) {
      var oldPriority = hw.getWalkedRecord().priority;
      gs.info('Incident priority in update number ' + hw.getUpdateNumber() + ' was ' + oldPriority);
    }

Output:

    Incident priority in update number 5 was 2
    Incident priority in update number 4 was 4
    Incident priority in update number 3 was 4
    Incident priority in update number 2 was 4
    Incident priority in update number 1 was 4
    Incident priority in update number 0 was 4

## HistoryWalker - walkForward() {#ariaid-title18}

Applies the appropriate history/audit data to get a walked GlideRecord to the state
when it was one update number forward. If next update count is missing from the history/audit
data, it will walk to the next available update count.
{#HW-walkForward__table_spm_bzs_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| None |   |   |
[Table 31. Parameters]

{#HW-walkForward__table_spm_bzs_qbb} {#HW-walkForward__table_tpm_bzs_qbb__entry__2}

| Type | Description |
|-|-|
| Boolean | Flag that indicates whether walking to the specified update number was possible. Valid values: * true: Able to walk to the specified update number. * false: Unable to walk to the specified update number. Possible reasons: Already walked to the GlideRecord update count. |
[Table 32. Returns]

{#HW-walkForward__table_tpm_bzs_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');
    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());

    while (hw.walkForward()) {
      var oldPriority = hw.getWalkedRecord().priority;
      gs.info('Incident priority in update number ' + hw.getUpdateNumber() + ' was ' + oldPriority);
    }

Output:

    Incident priority in update number 0 was 4
    Incident priority in update number 1 was 4
    Incident priority in update number 2 was 4
    Incident priority in update number 3 was 4
    Incident priority in update number 4 was 4
    Incident priority in update number 5 was 2
     
## HistoryWalker - walkTo(int updateCount) {#ariaid-title19}

Applies the appropriate history/audit data to get a GlideRecord to the state it was in a specific update count. Use getWalkedRecord() or getWalkedRecordCopy() after walking to an update
number to retrieve the "walked" GlideRecord.
Note:  
This method is not supported by the checkpoint walker implementation. Call the [HistoryWalker - walkTo(String checkpoint)](https://servicenow-prod.fluidtopics.net/AObx4IWpeG_DRNc1tk~rgA#HW-walkTo_S "Applies the appropriate history/audit data to get a GlideRecord to the state it was in for a specific record internal checkpoint. Use the getWalkedRecord() or getWalkedRecordCopy() method after walking to a record's internal checkpoint to retrieve the \"walked\" GlideRecord.") method when using the checkpoint walker.
{#HW-walkTo_I__table_pjv_jys_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| updateCount | Integer | Update number to walk to. |
[Table 33. Parameters]

{#HW-walkTo_I__table_pjv_jys_qbb} {#HW-walkTo_I__table_qjv_jys_qbb__entry__2}

| Type | Description |
|-|-|
| Boolean | Flag that indicates whether walking to the specified update number was possible. Valid values: * true: Able to walk to the specified update number. * false: Unable to walk to the specified update number. Possible reasons: The requested update is greater than the update count of the GlideRecord or there is no history/audit data for the requested update number. |
[Table 34. Returns]

{#HW-walkTo_I__table_qjv_jys_qbb}  
The following code example shows how to call this method.

    var incGr = new GlideRecord('incident');
    incGr.get('number', 'INC0000015');

    var hw = new sn_hw.HistoryWalker(incGr.getTableName(), incGr.getUniqueValue());
    if (hw.walkTo(3)) {
        var oldPriority = hw.getWalkedRecord().priority;
        gs.info('Incident priority in update number ' + hw.getUpdateNumber() + ' was ' + oldPriority);
    } else
        gs.info('Incident does not have update number 3');

Output:

    Incident priority in update number 3 was 4

## HistoryWalker - walkTo(String checkpoint) {#ariaid-title20}

Applies the appropriate history/audit data to get a GlideRecord to the state it was in for a specific record internal checkpoint. Use the getWalkedRecord() or getWalkedRecordCopy() method
after walking to a record's internal checkpoint to retrieve the "walked" GlideRecord.
Note:  
This method is only supported by the checkpoint walker implementation.
{#HW-walkTo_S__table_pjv_jys_qbb__entry__3}

| Name | Type | Description |
|-|-|-|
| checkpoint | String | Record's internal checkpoint to walk to. You can find this value in the internal_checkpoint field of the Sys Audit \[sys_audit\] or History \[sys_history_line\] table. |
[Table 35. Parameters]

{#HW-walkTo_S__table_pjv_jys_qbb} {#HW-walkTo_S__table_qjv_jys_qbb__entry__2}

| Type | Description |
|-|-|
| Boolean | Flag that indicates whether walking to the specified record's internal checkpoint was possible. Possible values: * true: Able to walk to the specified record's internal checkpoint. * false: Unable to walk to the specified record's internal checkpoint. Possible reasons: The internal checkpoint doesn't exist. |
[Table 36. Returns]

{#HW-walkTo_S__table_qjv_jys_qbb}  
The following code example shows how to call this method to walk through the changes made to the GlideRecord.


    var gr_Hw = new GlideRecord('sc_req_item');
    gr_Hw.get('b0d3335d49534210f877468e89703a7c');
     
    var hw = new sn_hw.HistoryWalker(gr_Hw.getTableName(), gr_Hw.getUniqueValue(), 'CHECKPOINT');
    hw.walkTo('19096afcc800000001');
    printChangedFields(hw);
     
    function printChangedFields(hw) {
       var walkedGr = hw.getWalkedRecord();
       var fields = GlideScriptRecordUtil.get(walkedGr).getChangedFieldNames();
       gs.info('Fields changed at update ' + hw.getUpdateNumber() + ' were:');
       for (var j = 0; j < fields.size(); j++) {
          var fieldName = fields.get(j) + '';
          if (fieldName !== 'variables')
             gs.info(walkedGr.getValue('sys_updated_on') + ' ' + fieldName + '=' + walkedGr.getValue(fieldName));
       }
     
       var variables = walkedGr.variables;
       for (var variableName in variables) {
          if (variables[variableName].changes())
             gs.info(walkedGr.getValue('sys_updated_on') + ' ' + variableName + '=' + variables[variableName].getValue());
       }
       gs.info('');
    }

Output:

    Fields changed at update 3 were:
    2024-07-09 08:50:21 price=1499
    2024-07-09 08:50:21 state=2
    2024-07-09 08:50:21 priority=2
    2024-07-09 08:50:21 recurring_price=100