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alguidelines/navpatterns/1-patterns/observer/index.html
TheDoubleH 2c5e80a8bf deploy: dd680561a2
2021-12-14 20:39:29 +00:00

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<ul class=topics>
<li data-nav-id=/welcome/ title=Welcome class=dd-item><a href=/welcome/><b><i class="fas fa-home"></i> </b>Welcome</a><ul></ul></li>
<li data-nav-id=/bcpatterns/ title="BC Patterns" class=dd-item><a href=/bcpatterns/><b><i class="fas fa-clone"></i> </b>BC Patterns</a><ul>
<li data-nav-id=/bcpatterns/facade-pattern/ title="Facade Pattern" class=dd-item><a href=/bcpatterns/facade-pattern/>Facade Pattern</a></li>
<li data-nav-id=/bcpatterns/generic-method-pattern/ title="Generic Method Pattern" class=dd-item><a href=/bcpatterns/generic-method-pattern/>Generic Method Pattern</a></li></ul></li>
<li data-nav-id=/bcbestpractices/ title="BC Dev. Best Practices" class=dd-item><a href=/bcbestpractices/><b><i class="fas fa-medal"></i> </b>BC Dev. Best Practices</a><ul>
<li data-nav-id=/bcbestpractices/readability/ title=Readability class=dd-item><a href=/bcbestpractices/readability/>Readability</a><ul>
<li data-nav-id=/bcbestpractices/readability/variable-naming/ title="Variable Naming" class=dd-item><a href=/bcbestpractices/readability/variable-naming/>Variable Naming</a></li>
<li data-nav-id=/bcbestpractices/readability/variables-declarations-order/ title="Variables Declarations Order" class=dd-item><a href=/bcbestpractices/readability/variables-declarations-order/>Variables Declarations Order</a></li></ul></li></ul></li>
<li data-nav-id=/navpatterns/ title="NAV Patterns Archive" class="dd-item parent"><a href=/navpatterns/><b><i class="fas fa-save"></i> </b>NAV Patterns Archive</a><ul>
<li data-nav-id=/navpatterns/1-patterns/ title="1. Patterns" class="dd-item parent"><a href=/navpatterns/1-patterns/>1. Patterns</a><ul>
<li data-nav-id=/navpatterns/1-patterns/activity-log/ title="Activity Logs" class=dd-item><a href=/navpatterns/1-patterns/activity-log/>Activity Logs</a></li>
<li data-nav-id=/navpatterns/1-patterns/argument-table/ title="Argument Table" class=dd-item><a href=/navpatterns/1-patterns/argument-table/>Argument Table</a></li>
<li data-nav-id=/navpatterns/1-patterns/blocked-entity/ title="Blocked Entity" class=dd-item><a href=/navpatterns/1-patterns/blocked-entity/>Blocked Entity</a><ul>
<li data-nav-id=/navpatterns/1-patterns/blocked-entity/data-driven-blocked-entity/ title="Data Driven Blocked Entity" class=dd-item><a href=/navpatterns/1-patterns/blocked-entity/data-driven-blocked-entity/>Data Driven Blocked Entity</a></li></ul></li>
<li data-nav-id=/navpatterns/1-patterns/cached-web-service-calls/ title="Cached Web Server Calls" class=dd-item><a href=/navpatterns/1-patterns/cached-web-service-calls/>Cached Web Server Calls</a></li>
<li data-nav-id=/navpatterns/1-patterns/conditional-cascading-update/ title="Conditional Cascading Update" class=dd-item><a href=/navpatterns/1-patterns/conditional-cascading-update/>Conditional Cascading Update</a></li>
<li data-nav-id=/navpatterns/1-patterns/copy-document/ title="Copy Document" class=dd-item><a href=/navpatterns/1-patterns/copy-document/>Copy Document</a></li>
<li data-nav-id=/navpatterns/1-patterns/create-data-from-templates/ title="Create Data from Templates" class=dd-item><a href=/navpatterns/1-patterns/create-data-from-templates/>Create Data from Templates</a></li>
<li data-nav-id=/navpatterns/1-patterns/create-urls-to-nav-clients/ title="Create URLs to NAV Clients" class=dd-item><a href=/navpatterns/1-patterns/create-urls-to-nav-clients/>Create URLs to NAV Clients</a></li>
<li data-nav-id=/navpatterns/1-patterns/creating-custom-charts/ title="Creating Custom Charts" class=dd-item><a href=/navpatterns/1-patterns/creating-custom-charts/>Creating Custom Charts</a></li>
<li data-nav-id=/navpatterns/1-patterns/cross-session-events/ title="Cross Session Events" class=dd-item><a href=/navpatterns/1-patterns/cross-session-events/>Cross Session Events</a></li>
<li data-nav-id=/navpatterns/1-patterns/currently-active-record/ title="Currently Active Record" class=dd-item><a href=/navpatterns/1-patterns/currently-active-record/>Currently Active Record</a></li>
<li data-nav-id=/navpatterns/1-patterns/data-migration-facade/ title="Data Migration Façade" class=dd-item><a href=/navpatterns/1-patterns/data-migration-facade/>Data Migration Façade</a></li>
<li data-nav-id=/navpatterns/1-patterns/discovery-event/ title="Discovery Event" class=dd-item><a href=/navpatterns/1-patterns/discovery-event/>Discovery Event</a></li>
<li data-nav-id=/navpatterns/1-patterns/document/ title=Document class=dd-item><a href=/navpatterns/1-patterns/document/>Document</a></li>
<li data-nav-id=/navpatterns/1-patterns/easy-update-of-setup-or-supplementary-information/ title="Easy Update Of Setup Or Supplementary Information" class=dd-item><a href=/navpatterns/1-patterns/easy-update-of-setup-or-supplementary-information/>Easy Update Of Setup Or Supplementary Information</a></li>
<li data-nav-id=/navpatterns/1-patterns/error-message-processing/ title="Error Message Processing" class=dd-item><a href=/navpatterns/1-patterns/error-message-processing/>Error Message Processing</a></li>
<li data-nav-id=/navpatterns/1-patterns/extending-the-role-center-headlines/ title="Extending the Role Center Headlines" class=dd-item><a href=/navpatterns/1-patterns/extending-the-role-center-headlines/>Extending the Role Center Headlines</a></li>
<li data-nav-id=/navpatterns/1-patterns/feature-localization-for-data-structures/ title="Feature Localization For Data Structures" class=dd-item><a href=/navpatterns/1-patterns/feature-localization-for-data-structures/>Feature Localization For Data Structures</a></li>
<li data-nav-id=/navpatterns/1-patterns/hooks/ title=Hooks class=dd-item><a href=/navpatterns/1-patterns/hooks/>Hooks</a></li>
<li data-nav-id=/navpatterns/1-patterns/implementation-of-surrogate-keys-using-autoincrement-pattern/ title="Surrogate keys using Autoincrement Pattern" class=dd-item><a href=/navpatterns/1-patterns/implementation-of-surrogate-keys-using-autoincrement-pattern/>Surrogate keys using Autoincrement Pattern</a></li>
<li data-nav-id=/navpatterns/1-patterns/instructions-in-the-ui/ title="Instructions in the UI" class=dd-item><a href=/navpatterns/1-patterns/instructions-in-the-ui/>Instructions in the UI</a></li>
<li data-nav-id=/navpatterns/1-patterns/integration-of-addresses/ title="Integration of Addresses" class=dd-item><a href=/navpatterns/1-patterns/integration-of-addresses/>Integration of Addresses</a></li>
<li data-nav-id=/navpatterns/1-patterns/journal-error-processing/ title="Journal Error Processing" class=dd-item><a href=/navpatterns/1-patterns/journal-error-processing/>Journal Error Processing</a></li>
<li data-nav-id=/navpatterns/1-patterns/journal-template-batch-line/ title="Journal Template Batch Line" class=dd-item><a href=/navpatterns/1-patterns/journal-template-batch-line/>Journal Template Batch Line</a></li>
<li data-nav-id=/navpatterns/1-patterns/master-data/ title="Master Data" class=dd-item><a href=/navpatterns/1-patterns/master-data/>Master Data</a></li>
<li data-nav-id=/navpatterns/1-patterns/multi-file-download/ title="Multi-file Download" class=dd-item><a href=/navpatterns/1-patterns/multi-file-download/>Multi-file Download</a></li>
<li data-nav-id=/navpatterns/1-patterns/multi-page-list/ title="Multi-Page List" class=dd-item><a href=/navpatterns/1-patterns/multi-page-list/>Multi-Page List</a></li>
<li data-nav-id=/navpatterns/1-patterns/multilanguage-application-data/ title="Multilanguage Application Data" class=dd-item><a href=/navpatterns/1-patterns/multilanguage-application-data/>Multilanguage Application Data</a></li>
<li data-nav-id=/navpatterns/1-patterns/net-exception-handling-in-cal/ title="NET Exception Handling in CAL" class=dd-item><a href=/navpatterns/1-patterns/net-exception-handling-in-cal/>NET Exception Handling in CAL</a><ul>
<li data-nav-id=/navpatterns/1-patterns/net-exception-handling-in-cal/tryfunction-net-exception-handling-in-cal/ title="TryFunction NET Exception Handling in CAL" class=dd-item><a href=/navpatterns/1-patterns/net-exception-handling-in-cal/tryfunction-net-exception-handling-in-cal/>TryFunction NET Exception Handling in CAL</a></li></ul></li>
<li data-nav-id=/navpatterns/1-patterns/no-series/ title="No Series" class=dd-item><a href=/navpatterns/1-patterns/no-series/>No Series</a></li>
<li data-nav-id=/navpatterns/1-patterns/notifications/ title=Notifications class=dd-item><a href=/navpatterns/1-patterns/notifications/>Notifications</a><ul>
<li data-nav-id=/navpatterns/1-patterns/notifications/in-context-notifications/ title="In-context Notifications" class=dd-item><a href=/navpatterns/1-patterns/notifications/in-context-notifications/>In-context Notifications</a></li>
<li data-nav-id=/navpatterns/1-patterns/notifications/notification-lifecycle-management-pattern/ title="Notification Lifecycle Management Pattern" class=dd-item><a href=/navpatterns/1-patterns/notifications/notification-lifecycle-management-pattern/>Notification Lifecycle Management Pattern</a></li></ul></li>
<li data-nav-id=/navpatterns/1-patterns/observer/ title=Observer class="dd-item active"><a href=/navpatterns/1-patterns/observer/>Observer</a></li>
<li data-nav-id=/navpatterns/1-patterns/posting-routine-select-behavior/ title="Posting Routine - Select Behavior" class=dd-item><a href=/navpatterns/1-patterns/posting-routine-select-behavior/>Posting Routine - Select Behavior</a></li>
<li data-nav-id=/navpatterns/1-patterns/product-name/ title="Product Name" class=dd-item><a href=/navpatterns/1-patterns/product-name/>Product Name</a></li>
<li data-nav-id=/navpatterns/1-patterns/queries/ title=Queries class=dd-item><a href=/navpatterns/1-patterns/queries/>Queries</a><ul>
<li data-nav-id=/navpatterns/1-patterns/queries/select-distinct-with-queries/ title="SELECT DISTINCT with Queries" class=dd-item><a href=/navpatterns/1-patterns/queries/select-distinct-with-queries/>SELECT DISTINCT with Queries</a></li>
<li data-nav-id=/navpatterns/1-patterns/queries/use-queries-to-detect-duplicate-records/ title="Use Queries to Detect Duplicate Records" class=dd-item><a href=/navpatterns/1-patterns/queries/use-queries-to-detect-duplicate-records/>Use Queries to Detect Duplicate Records</a></li>
<li data-nav-id=/navpatterns/1-patterns/queries/use-queries-to-replace-nested-loops/ title="Use Queries to Replace Nested Loops" class=dd-item><a href=/navpatterns/1-patterns/queries/use-queries-to-replace-nested-loops/>Use Queries to Replace Nested Loops</a></li></ul></li>
<li data-nav-id=/navpatterns/1-patterns/read-once-initialization-and-validation/ title="Read-once Initialization and Validation" class=dd-item><a href=/navpatterns/1-patterns/read-once-initialization-and-validation/>Read-once Initialization and Validation</a></li>
<li data-nav-id=/navpatterns/1-patterns/released-entity/ title="Released Entity" class=dd-item><a href=/navpatterns/1-patterns/released-entity/>Released Entity</a></li>
<li data-nav-id=/navpatterns/1-patterns/report-selection/ title="Report Selection" class=dd-item><a href=/navpatterns/1-patterns/report-selection/>Report Selection</a></li>
<li data-nav-id=/navpatterns/1-patterns/security/ title=Security class=dd-item><a href=/navpatterns/1-patterns/security/>Security</a><ul>
<li data-nav-id=/navpatterns/1-patterns/security/1-sensitive-data-encapsulation/ title="Sensitive Data Encapsulation" class=dd-item><a href=/navpatterns/1-patterns/security/1-sensitive-data-encapsulation/>Sensitive Data Encapsulation</a></li>
<li data-nav-id=/navpatterns/1-patterns/security/2-data-encryption/ title="Data Encryption" class=dd-item><a href=/navpatterns/1-patterns/security/2-data-encryption/>Data Encryption</a></li>
<li data-nav-id=/navpatterns/1-patterns/security/3-single-point-of-access/ title="Single Point of Access" class=dd-item><a href=/navpatterns/1-patterns/security/3-single-point-of-access/>Single Point of Access</a></li>
<li data-nav-id=/navpatterns/1-patterns/security/4-masked-text/ title="Masked Text" class=dd-item><a href=/navpatterns/1-patterns/security/4-masked-text/>Masked Text</a></li>
<li data-nav-id=/navpatterns/1-patterns/security/5-ssl-in-nav/ title="SSL in NAV" class=dd-item><a href=/navpatterns/1-patterns/security/5-ssl-in-nav/>SSL in NAV</a></li></ul></li>
<li data-nav-id=/navpatterns/1-patterns/setup-specificity-fallback/ title="Setup Specificity Fallback" class=dd-item><a href=/navpatterns/1-patterns/setup-specificity-fallback/>Setup Specificity Fallback</a></li>
<li data-nav-id=/navpatterns/1-patterns/silent-file-upload-and-download/ title="Silent File Upload and Download" class=dd-item><a href=/navpatterns/1-patterns/silent-file-upload-and-download/>Silent File Upload and Download</a></li>
<li data-nav-id=/navpatterns/1-patterns/singleton/ title=Singleton class=dd-item><a href=/navpatterns/1-patterns/singleton/>Singleton</a><ul>
<li data-nav-id=/navpatterns/1-patterns/singleton/singleton-codeunit/ title="Singleton Codeunit" class=dd-item><a href=/navpatterns/1-patterns/singleton/singleton-codeunit/>Singleton Codeunit</a></li>
<li data-nav-id=/navpatterns/1-patterns/singleton/singleton-table/ title="Singleton Table" class=dd-item><a href=/navpatterns/1-patterns/singleton/singleton-table/>Singleton Table</a><ul>
<li data-nav-id=/navpatterns/1-patterns/singleton/singleton-table/cue-table/ title="Cue Table" class=dd-item><a href=/navpatterns/1-patterns/singleton/singleton-table/cue-table/>Cue Table</a></li>
<li data-nav-id=/navpatterns/1-patterns/singleton/singleton-table/setup-table/ title="Setup Table" class=dd-item><a href=/navpatterns/1-patterns/singleton/singleton-table/setup-table/>Setup Table</a></li></ul></li></ul></li>
<li data-nav-id=/navpatterns/1-patterns/standard-journal/ title="Standard Journal" class=dd-item><a href=/navpatterns/1-patterns/standard-journal/>Standard Journal</a></li>
<li data-nav-id=/navpatterns/1-patterns/temporary-dataset-report/ title="Temporary Dataset Report" class=dd-item><a href=/navpatterns/1-patterns/temporary-dataset-report/>Temporary Dataset Report</a></li>
<li data-nav-id=/navpatterns/1-patterns/totals-and-discounts-on-subpages-sales-and-purchases/ title="Totals and Discounts on Subpages Sales and Purchases" class=dd-item><a href=/navpatterns/1-patterns/totals-and-discounts-on-subpages-sales-and-purchases/>Totals and Discounts on Subpages Sales and Purchases</a></li>
<li data-nav-id=/navpatterns/1-patterns/transfer-custom-fields/ title="Transfer Custom Fields" class=dd-item><a href=/navpatterns/1-patterns/transfer-custom-fields/>Transfer Custom Fields</a></li>
<li data-nav-id=/navpatterns/1-patterns/variant-facade/ title="Variant Facade" class=dd-item><a href=/navpatterns/1-patterns/variant-facade/>Variant Facade</a></li></ul></li>
<li data-nav-id=/navpatterns/2-anti-patterns/ title="2. Anti-Patterns" class=dd-item><a href=/navpatterns/2-anti-patterns/>2. Anti-Patterns</a><ul>
<li data-nav-id=/navpatterns/2-anti-patterns/nav-upgrade/ title="Nav Upgrade" class=dd-item><a href=/navpatterns/2-anti-patterns/nav-upgrade/>Nav Upgrade</a></li>
<li data-nav-id=/navpatterns/2-anti-patterns/reusable-bugs/ title="Reusable Bugs" class=dd-item><a href=/navpatterns/2-anti-patterns/reusable-bugs/>Reusable Bugs</a></li></ul></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/ title="3. CAL Coding Guidelines" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/>3. CAL Coding Guidelines</a><ul>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/ title=Design class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/>Design</a><ul>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/by-reference-parameters/ title="By Reference Parameters" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/by-reference-parameters/>By Reference Parameters</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/class-coupling/ title="Class Coupling" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/class-coupling/>Class Coupling</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/cyclomatic-complexity/ title="Cyclomatic Complexity" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/cyclomatic-complexity/>Cyclomatic Complexity</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/encapsulate-local-functionality/ title="Encapsulate Local Functionality" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/encapsulate-local-functionality/>Encapsulate Local Functionality</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/findset-findfirst-findlast/ title="FINDSET FINDFIRST FINDLAST" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/findset-findfirst-findlast/>FINDSET FINDFIRST FINDLAST</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/initialized-variables/ title="Initialized Variables" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/initialized-variables/>Initialized Variables</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/maintainability-index/ title="Maintainability Index" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/maintainability-index/>Maintainability Index</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/parameter-placeholders/ title="Parameter Placeholders" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/parameter-placeholders/>Parameter Placeholders</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/static-object-invocation/ title="Static Object Invocation" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/static-object-invocation/>Static Object Invocation</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/unreachable-code/ title="Unreachable Code" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/unreachable-code/>Unreachable Code</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/unused-initialized-variables/ title="Unused Initialized Variables" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/unused-initialized-variables/>Unused Initialized Variables</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/unused-variables/ title="Unused Variables" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/unused-variables/>Unused Variables</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/variable-capacity-mismatch/ title="Variable Capacity Mismatch" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/variable-capacity-mismatch/>Variable Capacity Mismatch</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/design/with-scope-name-collision/ title="WITH Scope Name Collision" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/design/with-scope-name-collision/>WITH Scope Name Collision</a></li></ul></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/internally-used-dot-net-types/ title="Internally used DotNet Types" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/internally-used-dot-net-types/>Internally used DotNet Types</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/internationalization/ title=Internationalization class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/internationalization/>Internationalization</a><ul>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/internationalization/using-calcdate/ title="Using Calcdate" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/internationalization/using-calcdate/>Using Calcdate</a></li></ul></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/localizability/ title=Localizability class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/localizability/>Localizability</a><ul>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/localizability/captionml-for-system-tables/ title="CaptionML on System Pages" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/localizability/captionml-for-system-tables/>CaptionML on System Pages</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/localizability/fieldcaption-and-tablecaption/ title="FIELDCAPTION and TABLECAPTION" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/localizability/fieldcaption-and-tablecaption/>FIELDCAPTION and TABLECAPTION</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/localizability/global-text-constants/ title="Global Text Constants" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/localizability/global-text-constants/>Global Text Constants</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/localizability/use-text-constants/ title="Use Text Constants" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/localizability/use-text-constants/>Use Text Constants</a></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/localizability/using-optioncaptionml/ title="Using OptionCaptionML" class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/localizability/using-optioncaptionml/>Using OptionCaptionML</a></li></ul></li>
<li data-nav-id=/navpatterns/3-cal-coding-guidelines/readability/ title=Readability class=dd-item><a href=/navpatterns/3-cal-coding-guidelines/readability/>Readability</a><ul>
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<h1>Observer</h1>
<p><em>By Nikolai L&rsquo;Estrange, from TVision Technology Ltd. in the UK</em>
_</p>
<h3 id=abstract>Abstract</h3>
<p>Track all record changes against a defined table or set of tables.</p>
<h3 id=problem>Problem</h3>
<p>Microsoft Dynamics NAV has the built in ability to track all record changes against any table, however it does not always fire the triggers for every table.</p>
<h3 id=solution>Solution</h3>
<p>Create a setup table to define which other tables you want to track changes for, and optionally what triggers you want to fire, then link this up to the standard triggers in Codeunit 1.</p>
<p>Codeunit 1 Application Management contains the triggers OnDatabaseInsert, OnDatabaseModify, OnDatabaseDelete and OnDatabaseRename which are what we need to subscribe to in order to track record changes. However these triggers are only fired sometimes. This is determined by the parameters set in the function GetTableTriggerSetup, which is called once per table per session.</p>
<p>In order to define which tables we are interested in we can create a new table with the following fields:</p>
<pre><code>**Observable Table:**
&quot;Table ID&quot; Integer Object.ID WHERE (Type=CONST(Table))
TrackInsert Boolean \[optional\]
TrackModify Boolean \[optional\]
TrackDelete Boolean \[optional\]
TrackRename Boolean \[optional\]
</code></pre>
<p>Then we can create a Codeunit that will set the Table Trigger Setup parameters and also subscribe to the OnDatabase triggers.</p>
<pre><code>**LOCAL \[EventSubscriber\] GetTableTriggerSetup(TableId : Integer;VAR OnDatabaseInsert : Boolean;VAR OnDatabaseModify : Boolean;VAR OnDatabaseDelete : Boolean;VAR OnDatabaseRename : Boolean)**
IF Observable.GET(TableId) THEN BEGIN
IF Observable.TrackInsert THEN
OnDatabaseInsert := TRUE;
IF Observable.TrackModify THEN
OnDatabaseModify := TRUE;
IF Observable.TrackDelete THEN
OnDatabaseDelete := TRUE;
IF Observable.TrackRename THEN
OnDatabaseRename := TRUE;
END;
**LOCAL \[EventSubscriber\] OnDatabaseInsert(RecRef : RecordRef)**
IF Observable.Get(RecRef.NUMBER) AND Observable.TrackInsert THEN
//do something
**LOCAL \[EventSubscriber\] OnDatabaseModify(RecRef : RecordRef)**
IF Observable.Get(RecRef.NUMBER) AND Observable.TrackModify THEN
//do something
**LOCAL \[EventSubscriber\] OnDatabaseDelete(RecRef : RecordRef)**
IF Observable.Get(RecRef.NUMBER) AND Observable.TrackDelete THEN
//do something
**LOCAL \[EventSubscriber\] OnDatabaseRename(RecRef : RecordRef;xRecRef : RecordRef)**
IF Observable.Get(RecRef.NUMBER) AND Observable.TrackRename THEN
//do something
</code></pre>
<p><em><strong>Note:</strong></em> In NAV2016 all these functions can be EventSubscribers that subscribe to the functions in Codeunit 1 as per above, in earlier versions of NAV these functions will need to be Global and called explicitly from within the Codeunit 1 functions.</p>
<h3 id=nav-usages>NAV Usages</h3>
<p>Variations of this pattern exists in the standard product in:</p>
<ul>
<li>Codeunit 423 Change Log Management</li>
<li>Codeunit 5150 Integration Management. In this Codeunit the tables that fire triggers are hardcoded in C/AL.</li>
</ul>
<h3 id=consequences>Consequences</h3>
<p>It is important that in our GetTableTriggerSetup function we only ever set the parameters to <strong>TRUE</strong>, and <strong>never</strong> set them to <strong>FALSE</strong>. This is because there may be other Codeunits listening to the triggers for that table, e.g. Change Log. This is also why we check the setup again within each trigger.</p>
<h3 id=related-topics>Related Topics</h3>
<p>This pattern was originally described in the following blog:</p>
<p><a href=https://geeknikolai.wordpress.com/2015/10/30/observer-pattern-in-dynamics-nav-2016/>https://geeknikolai.wordpress.com/2015/10/30/observer-pattern-in-dynamics-nav-2016/</a></p>
<h3 id=nav-versions>NAV Versions</h3>
<ul>
<li>From NAV 2016 use the code as shown</li>
<li>For earlier versions see <em>Note</em> above</li>
</ul>
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