Freemarker JSON dump

example.ftl

<#assign foo><@objectToJson object=data.myobj /></#assign>
${foo?html}

<#macro objectToJson object>
    <@compress single_line=true>
        <#if object?is_hash || object?is_hash_ex>
            <#assign first="true">
        {
            <#list object?keys as key>
                <#if first="false">,</#if>
                <#assign foo = key />
                <#assign value><@objectToJson object=object[key]!"" /></#assign>
            "${key}": ${value?trim}
                <#assign first="false">
            </#list>
        }
        <#elseif object?is_enumerable>
            <#assign first="true">
        [
            <#list object as item>
                <#if first="false">,</#if>
                <#assign value><@objectToJson object=item /></#assign>
            ${value?trim}
                <#assign first="false">
            </#list>
        ]
        <#else>
        "${object?trim}"
        </#if>
    </@compress>
</#macro>

Great, thanks for sharing, will use in https://github.com/InseeFrLab/keycloakify

<#macro objectToJson object depth>
    <@compress>

        <#local isHash = false>
        <#attempt>
            <#local isHash = object?is_hash || object?is_hash_ex>
        <#recover>
            /* can't evaluate if object is hash */
            undefined
            <#return>
        </#attempt>
        <#if isHash>

            <#local keys = "">

            <#attempt>
                <#local keys = object?keys>
            <#recover>
                /* can't list keys of object */
                undefined
                <#return>
            </#attempt>

            {${'\n'}

            <#list keys as key>

                <#if key == "class">
                    /* skipping "class" property of object */
                    <#continue>
                </#if>

                <#local value = "">

                <#attempt>
                    <#local value = object[key]>
                <#recover>
                    /* couldn't dereference ${key} of object */
                    <#continue>
                </#attempt>

                <#if depth gt 4>
                    /* Avoid calling recustively too many times depth: ${depth}, key: ${key} */
                    <#continue>
                </#if>

                "${key}": <@objectToJson object=value depth=depth+1/>,

            </#list>

            }${'\n'}

            <#return>

        </#if>


        <#local isMethod = "">
        <#attempt>
            <#local isMethod = object?is_method>
        <#recover>
            /* can't test if object is a method */
            undefined
            <#return>
        </#attempt>

        <#if isMethod>
            undefined
            <#return>
        </#if>



        <#local isBoolean = "">
        <#attempt>
            <#local isBoolean = object?is_boolean>
        <#recover>
            /* can't test if object is a boolean */
            undefined
            <#return>
        </#attempt>

        <#if isBoolean>
            ${object?c}
            <#return>
        </#if>


        <#local isEnumerable = "">
        <#attempt>
            <#local isEnumerable = object?is_enumerable>
        <#recover>
            /* can't test if object is enumerable */
            undefined
            <#return>
        </#attempt>

        <#if isEnumerable>

            [${'\n'}

            <#list object as item>

                <@objectToJson object=item depth=depth+1/>,

            </#list>

            ]${'\n'}

            <#return>
        </#if>


        <#attempt>
            "${object?no_esc}"
        <#recover>
            /* couldn't convert into string non hash, non method, non boolean, non enumerable object */
            undefined;
            <#return>
        </#attempt>


    </@compress>
</#macro>
<script>

<#assign obj = .data_model>

<#assign foo><@objectToJson object=obj depth=0 /></#assign>

console.log(${foo});
console.log(JSON.parse(JSON.stringify(${foo})));

</script>