Empty string is truthy?

[shaunlimjin]

After upgrading to v2.2.3 from v1.1.1, I've noticed that conditionals that evaluate empty strings now return a "truthy" value.

The following: {?value}{value}{:else}{messages.phone_number_example}{/value}

used to display phone_number_example when value == "", but now prints [Object object] instead.

[jimmyhchan]

cannot reproduce:

Empty strings shows falsy for me.

I'm looking at a simple example using http://linkedin.github.io/dustjs/test/test.html and it is behaving as expected.

Can you provide an example of a template/json pair that is showing the problem?

[rragan]

Ditto. Cannot reproduce with: {?value}true{:else}false{/value}

var json = { value: "" }

This outputs false. Be sure there isn't an extra space between your quotes.

[shaunlimjin]

Sorry for the delayed response. To reproduce:

Template:

{#arguments.phoneNumberModel}{#phoneNumberParts}
        <input type="text" class="text required focused" id="msisdn" name="phoneNumberParts[0].value" value="{?value}{value}{:else}{messages.phone_number_example}{/value}" maxlength="{maxLength}"/>
{/phoneNumberParts}{/arguments.phoneNumberModel}

JSON:

{
    "arguments": {
        "phoneNumberModel": {
            "phoneNumberParts": [
                {
                    "pattern": "[0-9]{10,10}",
                    "maxLength": 10,
                    "minLength": 10,
                    "value": ""
                }
            ]
        }
    },
    "messages": {     
        "phone_number_example": {
            "value": "xxx xxx xxxx",
            "key": "testkey"
        }
    }
}

Output:

<input type="text" class="text required focused" id="msisdn" name="phoneNumberParts[0].value" value="[object Object]" maxlength="10"/>

It works fine if the "messages" object is removed from the json, leaving it like so:

{
    "arguments": {
        "phoneNumberModel": {
            "phoneNumberParts": [
                {
                    "pattern": "[0-9]{10,10}",
                    "maxLength": 10,
                    "minLength": 10,
                    "value": ""
                }
            ]
        }
    }
}

Again, everything was working fine in dust.js v1.1.1

[rragan]

The problem is here: value="{?value}{value}{:else}{messages.phone_number_example}{/value}"

Dust puts params on the context stack via their name so this creates a param that has a function call to evaluate the stuff in the quotes. When the function is evaluated the param name value blocks visibility of the actual data value "value". If you rename the param to "valu", things work as you expect. The order in which things are put on the stack (params) changed but it may change back. That is under discussion. That is why this broke.

Update: Hold that thought. There may be more going on.

Your example still outputs [Object object] because t{messages.phone_number_example} is an object.

[shaunlimjin]

Thanks for the response, Richard.

In my case, the reason why this broke is probably different. My project is also using the dust-helpers library along with version 1.6.3 of the i18next library. My guess there is a compatibility issue with i18next.

The truthy/falsy evaluation is actually working. The [Object object] being printed is actually the messages.phone_number_example object.

Please feel free to close this issue.

Thanks, Shaun