1. Getting Started
      1. Video Quick-Start Series
      2. Server Requirements
        1. MySQL 5.0.51 Issues
      3. Installation
        1. Basic Installation
          1. MODx Revolution on Debian
          2. Problems with WAMPServer 2.0i
          3. Lighttpd Guide
          4. Installation on a server running ModSecurity
          5. MODX and Suhosin
          6. Nginx Server Config
        2. Successful Installation, Now What Do I Do?
        3. Successful Installation, Now What Do I Do?
        4. Advanced Installation
        5. Git Installation
        6. Command Line Installation
          1. The Setup Config Xml File
        7. Troubleshooting Installation
        8. Using MODx Revolution from SVN
      4. An Overview of MODX
        1. Glossary of Revolution Terms
          1. Explanation of Directory Structure
        2. Roadmap
        3. MODX Revolution Framework Structure Ideology
        4. What's New in 2.3
    2. FAQs & Troubleshooting
      1. CMP Development FAQs & Troubleshooting
    3. Making Sites with MODX
      1. Structuring Your Site
        1. Resources
          1. Content Types
          2. Named Anchor
          3. Static Resource
          4. Symlink
            1. Using Resource Symlinks
          5. Weblink
        2. Templates
        3. Chunks
        4. Using Snippets
      2. Tag Syntax
      3. Customizing Content
        1. Template Variables
          1. Creating a Template Variable
          2. Adding a Custom TV Type - MODX 2.2
          3. Bindings
            1. CHUNK Binding
            2. DIRECTORY Binding
            3. EVAL Binding
            4. FILE Binding
            5. INHERIT Binding
            6. RESOURCE Binding
            7. SELECT Binding
          4. Template Variable Input Types
          5. Template Variable Output Types
            1. Date TV Output Type
            2. Delimiter TV Output Type
            3. HTML Tag TV Output Type
            4. Image TV Output Type
            5. URL TV Output Type
          6. Adding a Custom TV Input Type
          7. Adding a Custom TV Output Type
          8. Creating a multi-select box for related pages in your template
          9. Accessing Template Variable Values via the API
        2. Properties and Property Sets
        3. Input and Output Filters (Output Modifiers)
          1. Custom Output Filter Examples
      4. Commonly Used Template Tags
        1. Date Formats
    4. Administering Your Site
      1. Settings
        1. System Settings
          1. access_category_enabled
          2. date_timezone
          3. access_context_enabled
          4. access_resource_group_enabled
          5. allow_duplicate_alias
          6. allow_forward_across_contexts
          7. allow_multiple_emails
          8. allow_tags_in_post
          9. archive_with
          10. automatic_alias
          11. auto_check_pkg_updates
          12. auto_check_pkg_updates_cache_expire
          13. auto_menuindex
          14. base_help_url
          15. blocked_minutes
          16. cache_action_map
          17. cache_context_settings
          18. cache_db
          19. cache_db_expires
          20. cache_db_session
          21. cache_default
          22. cache_disabled
          23. cache_format
          24. cache_handler
          25. cache_json
          26. cache_json_expires
          27. cache_lang_js
          28. cache_lexicon_topics
          29. cache_noncore_lexicon_topics
          30. cache_resource
          31. cache_resource_expires
          32. cache_scripts
          33. cache_system_settings
          34. clear_cache_refresh_trees
          35. compress_css
          36. compress_js
          37. concat_js
          38. container_suffix
          39. cultureKey
          40. custom_resource_classes
          41. default_per_page
          42. default_template
          43. editor_css_path
          44. editor_css_selectors
          45. emailsender
          46. emailsubject
          47. enable_dragdrop
          48. error_page
          49. extension_packages
          50. failed_login_attempts
          51. feed_modx_news
          52. feed_modx_news_enabled
          53. feed_modx_security
          54. feed_modx_security_enabled
          55. fe_editor_lang
          56. filemanager_path
          57. filemanager_path_relative
          58. filemanager_url
          59. filemanager_url_relative
          60. forgot_login_email
          61. friendly_alias_lowercase_only
          62. forward_merge_excludes
          63. friendly_alias_max_length
          64. friendly_alias_restrict_chars
          65. friendly_alias_restrict_chars_pattern
          66. friendly_alias_strip_element_tags
          67. friendly_alias_translit
          68. friendly_alias_translit_class
          69. friendly_alias_translit_class_path
          70. friendly_alias_trim_chars
          71. friendly_alias_urls
          72. friendly_alias_word_delimiter
          73. friendly_alias_word_delimiters
          74. friendly_urls
          75. friendly_url_prefix
          76. friendly_url_suffix
          77. global_duplicate_uri_check
          78. hidemenu_default
          79. link_tag_scheme
          80. mail_charset
          81. mail_encoding
          82. mail_smtp_auth
          83. mail_smtp_helo
          84. mail_smtp_hosts
          85. mail_smtp_keepalive
          86. mail_smtp_pass
          87. mail_smtp_port
          88. mail_smtp_prefix
          89. mail_smtp_single_to
          90. mail_smtp_timeout
          91. mail_smtp_user
          92. mail_use_smtp
          93. manager_date_format
          94. manager_direction
          95. manager_favicon_url
          96. manager_language
          97. manager_lang_attribute
          98. manager_theme
          99. manager_time_format
          100. context_tree_sort
          101. context_tree_sortby
          102. context_tree_sortdir
          103. session_enabled
          104. upload_files
          105. modx_charset
          106. new_file_permissions
          107. new_folder_permissions
          108. password_generated_length
          109. password_min_length
          110. phpthumb_allow_src_above_docroot
          111. phpthumb_cache_maxage
          112. phpthumb_cache_maxfiles
          113. phpthumb_cache_maxsize
          114. phpthumb_cache_source_enabled
          115. phpthumb_document_root
          116. phpthumb_error_bgcolor
          117. phpthumb_error_fontsize
          118. phpthumb_error_textcolor
          119. phpthumb_far
          120. phpthumb_imagemagick_path
          121. phpthumb_nohotlink_enabled
          122. phpthumb_nohotlink_erase_image
          123. phpthumb_nohotlink_text_message
          124. phpthumb_nohotlink_valid_domains
          125. phpthumb_nooffsitelink_enabled
          126. phpthumb_nooffsitelink_erase_image
          127. phpthumb_nooffsitelink_require_refer
          128. phpthumb_nooffsitelink_text_message
          129. phpthumb_nooffsitelink_valid_domains
          130. phpthumb_nooffsitelink_watermark_src
          131. phpthumb_zoomcrop
          132. principal_targets
          133. proxy_auth_type
          134. proxy_host
          135. proxy_password
          136. proxy_port
          137. proxy_username
          138. publish_default
          139. rb_base_dir
          140. rb_base_url
          141. request_controller
          142. request_param_alias
          143. request_param_id
          144. resource_tree_node_name
          145. resource_tree_node_tooltip
          146. richtext_default
          147. search_default
          148. server_offset_time
          149. server_protocol
          150. session_cookie_domain
          151. session_cookie_lifetime
          152. session_cookie_path
          153. session_cookie_secure
          154. session_handler_class
          155. session_name
          156. settings_version
          157. signupemail_message
          158. site_name
          159. site_start
          160. site_status
          161. site_unavailable_message
          162. site_unavailable_page
          163. strip_image_paths
          164. symlink_merge_fields
          165. tree_default_sort
          166. tree_root_id
          167. tvs_below_content
          168. udperms_allowroot
          169. ui_debug_mode
          170. unauthorized_page
          171. upload_maxsize
          172. use_alias_path
          173. use_browser
          174. use_editor
          175. use_multibyte
          176. welcome_screen
          177. which_editor
          178. which_element_editor
          179. xhtml_urls
      2. Using Friendly URLs
      3. Contexts
        1. Creating a Subdomain from a Folder using Virtual Hosts
        2. Using One Gateway Plugin to Manage Multiple Domains
      4. Customizing the Manager
        1. Customizing the Manager via Plugins
        2. Form Customization Profiles
        3. Form Customization Sets
          1. Customizing Tabs via Form Customization
          2. MODX GitHub Contributor's Guide
        4. Manager Templates and Themes
      5. MODX GitHub Integrator's Guide
      6. Security
        1. Hardening MODX Revolution
        2. Policies
          1. ACLs
          2. Permissions
            1. Permissions - Administrator Policy
            2. Permissions - Resource Policy
          3. PolicyTemplates
        3. Resource Groups
        4. Roles
        5. Security Standards
        6. Security Tutorials
          1. More on the Anonymous User Group
          2. Creating a Second Super Admin User
          3. Giving a User Manager Access
          4. Making Member-Only Pages
          5. Restricting an Element from Users
        7. Troubleshooting Security
          1. Resetting a User Password Manually
        8. User Groups
        9. Users
      7. Installing a Package
        1. Troubleshooting Package Management
      8. Upgrading MODX
        1. Upgrading to Revolution 2.0.5
        2. Upgrading from 2.0.x to 2.1.x
        3. Upgrading from Versions Earlier than 2.0.5
        4. Upgrading to 2.2.x
        5. Upgrading to Revolution 2.0.0-rc-2
        6. Troubleshooting Upgrades
        7. Upgrading from MODx Evolution
          1. Functional Changes from Evolution
      9. Moving Your Site to a New Server, or to Root from Subfolder
      10. Media Sources
        1. Adding a Media Source
        2. Assigning Media Sources to TVs
        3. Media Source Types
          1. Media Source Type - File System
          2. Media Source Type - S3
        4. Securing a Media Source
          1. Creating a Media Source for Clients Tutorial
      11. Dashboards
        1. Assigning a Dashboard to a User Group
        2. Creating a Dashboard Widget
        3. Dashboard Widget Types
          1. Dashboard Widget Type - File
          2. Dashboard Widget Type - HTML
          3. Dashboard Widget Type - Inline PHP
          4. Dashboard Widget Type - Snippet
        4. Managing Your Dashboard
    5. Developing in MODX
      1. Code Standards
      2. Overview of MODX Development
        1. Developer Introduction
          1. Getting Started Developing
        2. Extras Directories
        3. Setting up a Development Environment
      3. Basic Development
        1. Static Elements
        2. Plugins
          1. System Events
            1. OnMODXInit
            2. OnFileManagerBeforeUpload
            3. OnFileManagerDirCreate
            4. OnFileManagerDirRemove
            5. OnFileManagerDirRename
            6. OnFileManagerFileCreate
            7. OnFileManagerFileRemove
            8. OnFileManagerFileRename
            9. OnFileManagerFileUpdate
            10. OnPackageInstall
            11. OnPackageUninstall
            12. OnPackageRemove
            13. OnBeforeCacheUpdate
            14. OnBeforeChunkFormDelete
            15. OnBeforeChunkFormSave
            16. OnBeforeDocFormDelete
            17. OnBeforeDocFormSave
            18. OnBeforeEmptyTrash
            19. OnBeforeManagerLogin
            20. OnBeforeManagerLogout
            21. OnBeforeManagerPageInit
            22. OnBeforePluginFormDelete
            23. OnBeforePluginFormSave
            24. OnBeforeSaveWebPageCache
            25. OnBeforeSnipFormDelete
            26. OnBeforeSnipFormSave
            27. OnBeforeTempFormDelete
            28. OnBeforeTempFormSave
            29. OnBeforeTVFormDelete
            30. OnBeforeTVFormSave
            31. OnBeforeUserActivate
            32. OnBeforeUserFormDelete
            33. OnBeforeUserFormSave
            34. OnBeforeWebLogin
            35. OnBeforeWebLogout
            36. OnCacheUpdate
            37. OnCategoryBeforeRemove
            38. OnCategoryBeforeSave
            39. OnCategoryRemove
            40. OnCategorySave
            41. OnChunkBeforeRemove
            42. OnChunkBeforeSave
            43. OnChunkFormDelete
            44. OnChunkFormPrerender
            45. OnChunkFormRender
            46. OnChunkFormSave
            47. OnChunkRemove
            48. OnChunkSave
            49. OnContextBeforeRemove
            50. OnContextBeforeSave
            51. OnContextFormPrerender
            52. OnContextFormRender
            53. OnContextRemove
            54. OnContextSave
            55. OnDocFormDelete
            56. OnDocFormPrerender
            57. OnDocFormRender
            58. OnDocFormSave
            59. OnDocPublished
            60. OnDocUnPublished
            61. OnEmptyTrash
            62. OnFileManagerUpload
            63. OnHandleRequest
            64. OnInitCulture
            65. OnLoadWebDocument
            66. OnLoadWebPageCache
            67. OnManagerAuthentication
            68. OnManagerLogin
            69. OnManagerLoginFormPrerender
            70. OnManagerLoginFormRender
            71. OnManagerLogout
            72. OnManagerPageAfterRender
            73. OnManagerPageBeforeRender
            74. OnManagerPageInit
            75. OnPageNotFound
            76. OnPageUnauthorized
            77. OnParseDocument
            78. OnPluginBeforeRemove
            79. OnPluginBeforeSave
            80. OnPluginEventRemove
            81. OnPluginFormDelete
            82. OnPluginFormPrerender
            83. OnPluginFormRender
            84. OnPluginFormSave
            85. OnPluginRemove
            86. OnPluginSave
            87. OnPropertySetBeforeRemove
            88. OnPropertySetBeforeSave
            89. OnPropertySetRemove
            90. OnPropertySetSave
            91. OnResourceGroupBeforeRemove
            92. OnResourceGroupBeforeSave
            93. OnResourceGroupRemove
            94. OnResourceGroupSave
            95. OnRichTextBrowserInit
            96. OnRichTextEditorInit
            97. OnRichTextEditorRegister
            98. OnSiteRefresh
            99. OnSiteSettingsRender
            100. OnTemplateVarBeforeRemove
            101. OnTemplateVarBeforeSave
            102. OnTemplateVarRemove
            103. OnTemplateVarSave
            104. OnUserActivate
            105. OnUserBeforeRemove
            106. OnUserBeforeSave
            107. OnUserChangePassword
            108. OnUserFormDelete
            109. OnUserFormSave
            110. OnUserNotFound
            111. OnUserRemove
            112. OnUserSave
            113. OnWebAuthentication
            114. OnWebLogin
            115. OnWebLogout
            116. OnWebPageComplete
            117. OnWebPageInit
            118. OnWebPagePrerender
        3. Snippets
          1. Adding CSS and JS to Your Pages Through Snippets
          2. How to Write a Good Chunk
          3. How to Write a Good Snippet
          4. Templating Your Snippets
        4. xPDO
      4. Advanced Development
        1. Caching
          1. Setting up Memcache in MODX
        2. Custom Manager Pages
          1. Custom Manager Pages in 2.3
          2. Actions and Menus
            1. Action List
          3. Custom Manager Pages Tutorial
          4. MODExt
            1. MODx.combo.ComboBox
            2. MODx.Console
            3. MODx.FormPanel
            4. MODx.grid.Grid
            5. MODx.grid.LocalGrid
            6. MODx.msg
            7. MODx.tree.Tree
            8. MODx.Window
            9. MODExt Tutorials
              1. 1. Ext JS Tutorial - Message Boxes
              2. 2. Ext JS Tutorial - Ajax Include
              3. 3. Ext JS Tutorial - Animation
              4. 4. Ext JS Tutorial - Manipulating Nodes
              5. 5. Ext JS Tutorial - Panels
              6. 7. Ext JS Tutoral - Advanced Grid
              7. 8. Ext JS Tutorial - Inside a CMP
            10. MODExt MODx Object
        3. Custom Resource Classes
          1. Creating a Resource Class
            1. Creating a Resource Class - Step 2
            2. Creating a Resource Class - Step 3
            3. Creating a Resource Class - Step 4
        4. Extending modUser
        5. From the Command Line (CLI)
        6. Internationalization
          1. Adding a Translation
        7. MODX Services
          1. modFileHandler
          2. modMail
          3. modRegistry
        8. Namespaces
        9. Package Management
          1. Package Dependencies
          2. Creating a 3rd Party Component Build Script
          3. Providers
          4. Transport Packages
        10. Using runProcessor
        11. Validating Requests: Tokens and Nonces
        12. Developing RESTful APIs
      5. Other Development Resources
        1. Summary of Legacy Code Removed in 2.1
        2. API Reference
        3. Class Reference
          1. modResource
            1. modResource.isMember
          2. modChunk
            1. modChunk.getContent
            2. modChunk.setContent
          3. modUser
            1. modUser.addSessionContext
            2. modUser.changePassword
            3. modUser.endSession
            4. modUser.getSessionContexts
            5. modUser.getSettings
            6. modUser.hasSessionContext
            7. modUser.isAuthenticated
            8. modUser.isMember
            9. modUser.loadAttributes
            10. modUser.removeSessionContext
            11. modUser.removeSessionContextVars
            12. modUser.removeSessionCookie
          4. modX
            1. modX.addEventListener
            2. modX.checkForLocks
            3. modX.checkSession
            4. modX.executeProcessor
            5. modX.getAuthenticatedUser
            6. modX.getCacheManager
            7. modX.getChildIds
            8. modX.getChunk
            9. modX.getConfig
            10. modX.getContext
            11. modX.getEventMap
            12. modX.getLoginUserID
            13. modX.getLoginUserName
            14. modX.getParentIds
            15. modX.getParser
            16. modX.getPlaceholder
            17. modX.getRegisteredClientScripts
            18. modX.getRegisteredClientStartupScripts
            19. modX.getRequest
            20. modX.getResponse
            21. modX.getService
            22. modX.getSessionState
            23. modX.getTree
            24. modX.getUser
            25. modX.getVersionData
            26. modX.handleRequest
            27. modX.hasPermission
            28. modX.initialize
            29. modX.invokeEvent
            30. modX.lexicon
            31. modX.makeUrl
            32. modX.parseChunk
            33. modX.regClientCSS
            34. modX.regClientHTMLBlock
            35. modX.regClientScript
            36. modX.regClientStartupHTMLBlock
            37. modX.regClientStartupScript
            38. modX.reloadConfig
            39. modX.removeAllEventListener
            40. modX.removeEventListener
            41. modX.runProcessor
            42. modX.runSnippet
            43. modX.sendError
            44. modX.sendErrorPage
            45. modX.sendForward
            46. modX.sendRedirect
            47. modX.sendUnauthorizedPage
            48. modX.setDebug
            49. modX.setPlaceholder
            50. modX.setPlaceholders
            51. modX.switchContext
            52. modX.toPlaceholder
            53. modX.toPlaceholders
            54. modX.unsetPlaceholder
            55. modX.unsetPlaceholders
        4. Loading MODX Externally
        5. Reserved Parameters
    6. Case Studies and Tutorials
      1. Developing an Extra in MODX Revolution
        1. Developing an Extra in MODX Revolution, Part II
        2. Developing an Extra in MODX Revolution, Part III
      2. Developing an Extra in MODX Revolution - MODX 2.1 and Earlier
        1. Developing an Extra in MODX Revolution, Part II - MODX 2.1 and Earlier
        2. Developing an Extra in MODX Revolution, Part III - MODX 2.1 and Earlier
      3. PHP Coding in MODx Revolution, Pt. I
        1. PHP Coding in MODx Revolution, Pt. II
        2. PHP Coding in MODx Revolution, Pt. III
      4. Using Custom Database Tables in your 3rd Party Components
      5. Creating a Blog in MODx Revolution
      6. Loading Pages in the Front-End via AJAX and jQuery Tabs
      7. Reverse Engineer xPDO Classes from Existing Database Table
      8. Integrating a Template into MODX Tutorial
      9. Quick and Easy MODX Tutorials
        1. Automated Server-Side Image Editing
      10. Adding Custom Fields to Manager Forms
      11. Create a Multilingual Website with migxMultiLang
      12. Managing Resources and Elements via SVN
    7. MODX Community Information
      1. Becoming a Core Contributor
      2. Filing Bug Reports
      3. Getting a MODx Account
      4. Using GitHub

Creating a multi-select box for related pages in your template

This brief tutorial will explain how you can make a client-proof  "Related pages" template variable. This specific example will introduce you to several MODX subjects including writing custom snippets and using custom output modifiers, however there are many different ways to achieve the same result. This tutorial will hopefully allow you to get a deeper understanding of several of the used concepts and help you further develop highly customizable content editing.

Setting up the Template Variable

Of course we will need a Template Variable. In the Manager, navigate to the Elements tab in the navigation structure and click the icon with a TV on it, or right click on the Template Variables section to create a new template variable. Give it a suitable name and caption (this tutorial assumes relatedPages).

In this case we will want to be able of selecting multiple resources, so we're going to choose the input type "Listbox (multi-select)", however you could also use the Checkbox type without adjusting the rest of this tutorial if you would rather have a list of checkboxes. 

Next link the Template Variable to the template that needs it on the "Template Access" tab, for example your blog item template.

To fill the template variable with some values, we will need to write simple snippet* and run it in the Input Options field. To do this we will be using what is known as an @BINDING. Add the following code to the Input Options field:

 @EVAL return $modx->runSnippet('listMyResources',array('parent' => 9));

This makes use of the @EVAL binding to wrap the rest of the input in an eval() PHP statement. This can be used to execute PHP, and therefore access the very powerful $modx object. We are then using that to use the runSnippet method which, well, runs a snippet, while passing the array in the second parameter as properties. In this case we are telling it that "parent" is equal to 9. The result of this snippet will then be returned - not echoed. This is needed to make sure it can be parsed and will not be placed on the page randomly.

You probably don't have a snippet called listMyResources yet, so let's create it.

* You don't *have* to write a snippet, you could use getResources for it as well, but to introduce you to a number of interesting methods while we're at it you may want to write your own. .

Creating the snippet

We will need to create a snippet that lists the appropriate resources, and in such a way that it makes sense to the TV input type. The Listbox will be expecting a string like the following:

value1==name||value2==name2||lasteone==Last name?

The above consists of three key-value pairs, seperated by two pipes. The key and value are separated by two equal characters. So this is what we want the snippet to output as well.

Create a new snippet and name it listMyResources or whatever you put in the input options of the template variable. Let's start of by assigning the property expected (parent) to a variable.

$parent = $modx->getOption('parent',$scriptProperties,9);

This sets the variable $parent to the value of any "parent" property found. This can be from an assigned property set or inline properties like in our situation. The 9 in the end is the default value to be used if there is no value found.

$parentObj = $modx->getObject('modResource',$parent);
if (!($parentObj instanceof modResource)) { return ''; }
$resArray = $parentObj->getMany('Children');

Then we will get the Object (abstraction) of the parent resource using the getObject method and assign it to a variable named parentObj. We check if we are dealing with a proper resource (ie, the resource with the id $parent existed and loaded into $parentObj just fine). After that we will set up the $resArray variable which is filled with an array of the parents' children if any.

Now that we have all the children we need, let's get the information we need from each aswell.

$resources = array();
foreach($resArray as $res) {
  if ($res instanceof modResource) {
    $resources[] = $res->get('pagetitle') . '==' . $res->get('id');

First we instantiate a new variable as an empty array. While not really required, it is good practice and can prevent injection of not-so-funny things elsewhere. Next we loop through the array with resources and when a valid resource, we store the id and pagetitle in a new entry in the $resources array. Note that we are putting it in with the two equal characters to put it in the right format for the TV.

Almost done!

$out = implode("||",$resources);
return $out;

We just glue together the array into a string, seperated by the two pipes (remember the tv input type syntax?) , and return it. Be sure not to echo it as that will make it show up whenever it is being called instead of when it is requested and can lead to unexpected results.

Now if you go to a resource and change it to the template linked to this template variable, you should see the a list of pages you can select.

For clarity, here's the complete snippet:

$parent = $modx->getOption('parent',$scriptProperties,9);
$parentObj = $modx->getObject('modResource',$parent);
if (!($parentObj instanceof modResource)) { return ''; }
$resArray = $parentObj->getMany('Children');
$resources = array();
foreach($resArray as $res) {
  if ($res instanceof modResource) {
    $resources[] = $res->get('pagetitle') . '==' . $res->get('id');
$out = implode("||",$resources);
return $out;

Presenting the related pages in your template

You can just put the TV tag in your template, but most likely that will just give you a bunch of numbers, representing the IDs of the selected resources. You'll want to do a few things. First of, go back to your template variable and set the Output type to "delimiter". You will be giving the option to specify what your delimiter will be, for example a comma or two pipes. Let's set it as a comma for this tutorial.

Now to show it in your template, we will want a snippet that fetches the resources based on the ID we got from the template variable, parse it in a chunk so we can display it in anyway we want to and then return it to the template.

We will assume this would be our snippet call:

 [[relatedPages? &input=`[[*relatedPages]]` &tpl=`relatedPagesTpl`]]

So we are setting an input property with the delimited list of resource IDs that we said were related, and a chunkname (relatedPagesTpl) to use as the chunk template.

Let's work on the snippet then. Why don't we start with fetching and checking the two properties we added?

if (empty($input)) { return 'This article is so unique, that we couldn\'t find anything related to it!'; }
$tpl = $modx->getOption('tpl',$scriptProperties,'relatedPagesTpl');
if ($modx->getChunk($tpl) == '') { return 'We found some related pages, but don\'t know how to present it.'; }

What you see here is first checking if the $input variable (derived from the &input property) is empty and return an error message if so. The reason we're using this directly and not in the way as shown with the $tpl variable (using modX::getOption) is because we could also use the snippet as an output filter, and when we do that we can assume the $input variable is set. More about output filters here. On the second line we are first assigning a value to $tpl, which is either the "tpl" property passed in the snippet call, or the default of 'relatedPagesTpl'. On the third line we fetch the chunk by its name using modX::getChunk, and if that is empty (so it does not exist, or is empty) we return a nice error message.

So now that we have the settings, we can start processing. Let's first split up the delimited list of IDs into an array using the explode function. We will also set up an empty array for our output.

$ids = explode(',', $input);
$output = array();

Now loop through the $ids array...

foreach ($ids as $key => $value) {
  // We will do something here in a minute

Within the loop we will want to get the resource object first, and to prevent we will create links that others can not access, we are making sure it has been published as well. You could add more conditions (for example, only when the 'hidemenu' field is set to 0, or only searchable resources will show up), but we are happy with this.

After we fetched the object, we are also going to make sure we found an object. If we don't, and a selected resource that was not published can potentially result in a nasty fatal PHP error being visible instead of your carefully handcrafted template with related pages... To be 100% sure, we are checking if the returned object is part of the "modResource" class.

foreach ($ids as $key => $value) {
  $resource = $modx->getObject('modResource',array(
    'published' => 1,
    'id' => $value));
  if ($resource instanceof modResource) {
    // We are sure we have a resource here, so let's do something!

Okay, so what do we want to do now? Let's just assume we want to call the chunk we assigned earlier, and put all resource fields into placeholders so we can call pretty much anything in there. For this we use the modElement::toArray() method to create an array of field => value pairs, and the modX::getChunk method (we also used that before, remember?) with the value array as second parameter to tell it to parse those as placeholders. We assign the result of that (which is the chunk with the placeholders parsed with the values we passed) to our $output array.

foreach ($ids as $key => $value) {
  $resource = $modx->getObject('modResource',array(
    'published' => 1,
    'id' => $value));
  if ($resource instanceof modResource) {
    $output[] = $modx->getChunk($tpl,$resource->toArray());

All we need to do now is return the $output array as a string and we have our related pages. The implode function glues together the different array items, using the first parameter (in this case an empty string) as delimiter. We could specify a comma-space in there to glue together with a comma in between, however in this case we wont.

return implode('',$output);

And that's it!

For clarity, this is the resulting snippet we named "relatedPages":

if (empty($input)) { return 'This article is so unique, that we couldn\'t find anything related to it!'; }
$tpl = $modx->getOption('tpl',$scriptProperties,'relatedPagesTpl');
if ($modx->getChunk($tpl) == '') { return 'We found some related pages, but don\'t know how to present it.'; }
$ids = explode(',', $input);
$output = array();
foreach ($ids as $key => $value) {
  $resource = $modx->getObject('modResource',array(
    'published' => 1,
    'id' => $value));
  if ($resource instanceof modResource) {
    $output[] = $modx->getChunk($tpl,$resource->toArray());
return implode('',$output);

An example of the relatedPagesTpl could be:

  <a href="[[~[[+id]]]]" title="[[+pagetitle]]">
  </a>, by [[+createdby:userinfo=`fullname`]]

This creates a list item with a link to the resource and its pagetitle as the title attribute. It will try to use the longtitle for the link text, but defaults to the pagetitle if the longtitle doesn't exist. It also uses the userinfo output modifier to add the fullname of the author of the resource to the list item. You can use any default resource field there.

Further reading..

When looking to also include TVs in your relatedPagesTpl chunk, you'll have to modify the snippet a bit.

Also, when you want to search multiple parents for resources you will need to adjust the first snippet as well.

A possible solution for both of these features can be found at http://forums.modx.com/thread/70087/related-pages-tv-display-images

Another similar question and its answer, relevant to the same: http://forums.modx.com/thread/70587/display-resources-selected-through-tv-urgent

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