Could not parse as expression defining a DataTable in Thymeleaf

Question

I have a basic SpringBoot 2.0.4.RELEASE app. using Spring Initializer, JPA, embedded Tomcat, Thymeleaf template engine, and package as an executable JAR file.

I have this definition of a datatable in a template

    <script th:inline="javascript">
            /*<![CDATA[*/ 

        $.fn.dataTable.ext.errMode = 'throw';

            var ajaxUrl = /*[[@{${ajaxUrl}}]]*/ "";

                var table = $('#smsEventTable').DataTable( {
                    order: [[ 0, "desc" ]],
                    select: true,
                    bLengthChange: false,
                    stateSave: true,
                    pageLength: 20,
                    ajax: ajaxUrl, 
                       "columns": [
                           { data: 'id' },
                           { data: 'smsId' },
                           { data: 'companyName' },
                           { data: 'description' },
                           { data: 'battery', className: 'col_battery' },
                           { data: 'dateTime' },
                           { data: 'signal' },           
                           { data: 'data' },
                           { data: 'alarm' }
                       ] 
                });

            /*]]>*/
</script>

But the first time I load the page and there is no data I got this error:

Caused by: org.thymeleaf.exceptions.TemplateProcessingException: Could not parse as expression: " 0, "desc" " (template: "/sms/smsList" - line 273, col 12)

Answer 1

The problem here is this expression: order: [[ 0, "desc" ]],. Because that expression has double brackets ([[ and ]]), Thymeleaf is trying to evaluate it as an inline expression. The simplest way to fix this is to format it differently by break up the brackets:

order: [ [0, "desc"] ],

or

order: [
    [0, "desc"]
],

You could also break up your JavaScript into two blocks (disabling inlining in the second one) like this:

<script th:inline="javascript">
    var ajaxUrl = /*[[@{${ajaxUrl}}]]*/ "";
</script>

<script th:inline="none">
/*<![CDATA[*/ 
    $.fn.dataTable.ext.errMode = 'throw';

    var table = $('#smsEventTable').DataTable({
        order: [[0, "desc"]],
        select: true,
        bLengthChange: false,
        stateSave: true,
        pageLength: 20,
        ajax: ajaxUrl, 
           "columns": [
               {data: 'id'},
               {data: 'smsId'},
               {data: 'companyName'},
               {data: 'description'},
               {data: 'battery', className: 'col_battery'},
               {data: 'dateTime'},
               {data: 'signal'},           
               {data: 'data'},
               {data: 'alarm'}
           ] 
    });
/*]]>*/
</script>

Answer 2

Break the square brackets as follows,

order: [
   [0, "desc"]
],