{"id":668,"date":"2022-07-06T21:28:00","date_gmt":"2022-07-07T02:28:00","guid":{"rendered":"https:\/\/blog.felineflock.com\/?p=668"},"modified":"2024-01-03T21:40:29","modified_gmt":"2024-01-04T03:40:29","slug":"how-to-use-track-with-complex-types-in-lightning-web-components","status":"publish","type":"post","link":"https:\/\/blog.felineflock.com\/index.php\/2022\/07\/06\/how-to-use-track-with-complex-types-in-lightning-web-components\/","title":{"rendered":"How to Use @track with Complex Types in Lightning Web Components"},"content":{"rendered":"\n
\"\"<\/figure>\n\n\n\n

Did you know that you can pass complex types of data from Lightning Web Components to Apex controllers?<\/p>\n\n\n\n

I’ve recently implemented a Lightning data table<\/a> with pagination and sorting so I’ve created a data structure “queryParameters” like this (*):<\/p>\n\n\n\n

@track queryParameters = { <\/code><\/p>\n\n\n\n

sortFieldName: '', <\/code><\/p>\n\n\n\n

sortDirection: '', <\/code><\/p>\n\n\n\n

pageNumber: 1, <\/code><\/p>\n\n\n\n

pageSize: 8 <\/code><\/p>\n\n\n\n

};<\/code><\/p>\n\n\n\n

Then I’ve referenced the queryParameters variable in a @wire call to an Apex controller as below: <\/p>\n\n\n\n

@wire( getAvailableRecords, { queryParameters: '$queryParameters' } )<\/code><\/p>\n\n\n\n

Then found a couple of interesting details:<\/p>\n\n\n\n

    \n
  1. The Apex method will require a Map<Object, Object> or Map<Object, String><\/strong> for complex\/composite Javascript types such as “queryParameters”. The parameter will not be received if you declare it as a class with @AuraEnabled members. You will have to receive it as a Map instead.<\/li>\n\n\n\n
  2. If you change a member of the object queryParameters, even though you’ve annotated it with @track (*), it won’t track and the component will not rerender. You will have to modify the queryParameters object entirely – instead of just one of its members – to cause the expected reaction (that is, the @wire method should be called when queryParameters changes).<\/li>\n<\/ol>\n\n\n\n

    So I’ve ended up coding the changes to queryParameters like below, to cause @track to not ignore changes: <\/p>\n\n\n\n

    <\/merlin-component><\/merlin-component>\/\/ refresh data when page is changed <\/code><\/p>\n\n\n\n

    <\/merlin-component>this.queryParameters = { <\/code><\/p>\n\n\n\n

    <\/merlin-component> ...this.queryParameters, <\/code><\/p>\n\n\n\n

    <\/merlin-component> pageNumber: pageNumber <\/code><\/p>\n\n\n\n

    };<\/code><\/p>\n\n\n\n

    ... <\/code><\/p>\n\n\n\n

    \/\/ refresh data when sorting criteria is changed<\/code><\/p>\n\n\n\n

    this.queryParameters = { <\/code><\/p>\n\n\n\n

    ...this.queryParameters, <\/code><\/p>\n\n\n\n

    sortFieldName: fieldName, <\/code><\/p>\n\n\n\n

    sortDirection: sortDirection <\/code><\/p>\n\n\n\n

    }<\/code><\/p>\n\n\n\n

    (*) @track is no longer needed since Spring ’20 release<\/a> and all fields in a LWC class are reactive. @track was mentioned to make the point clear.<\/p>\n\n\n\n

    It is interesting though that the observed behavior is exactly opposite of what is described in Spring ’20 and has been reported as a bug<\/a>.<\/p>\n\n\n\n

    Thanks to Krishna Teja<\/a> for this article that gave more clarity on passing complex data types from LWC to Apex<\/a>!<\/p>\n","protected":false},"excerpt":{"rendered":"

    Did you know that you can pass complex types of data from Lightning Web Components to Apex controllers? I’ve recently implemented a Lightning data table with pagination and sorting so I’ve created a data structure “queryParameters” like this (*): @track queryParameters = { sortFieldName: ”, sortDirection: ”, pageNumber: 1, pageSize: 8 }; Then I’ve referenced […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-668","post","type-post","status-publish","format-standard","hentry","category-blog"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/blog.felineflock.com\/index.php\/wp-json\/wp\/v2\/posts\/668","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.felineflock.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.felineflock.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.felineflock.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.felineflock.com\/index.php\/wp-json\/wp\/v2\/comments?post=668"}],"version-history":[{"count":1,"href":"https:\/\/blog.felineflock.com\/index.php\/wp-json\/wp\/v2\/posts\/668\/revisions"}],"predecessor-version":[{"id":670,"href":"https:\/\/blog.felineflock.com\/index.php\/wp-json\/wp\/v2\/posts\/668\/revisions\/670"}],"wp:attachment":[{"href":"https:\/\/blog.felineflock.com\/index.php\/wp-json\/wp\/v2\/media?parent=668"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.felineflock.com\/index.php\/wp-json\/wp\/v2\/categories?post=668"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.felineflock.com\/index.php\/wp-json\/wp\/v2\/tags?post=668"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}