Coldbox and VueJS untangled

Month: January 2020

Input validation with full null support

Adobe introduced full null support in ColdFusion 2018. Before 2018 null values returned by databases and external systems were converted to empty strings. This behaviour made it almost impossible to distinguish between empty strings and null values, and also caused issues with serialization and deserialization. You also had to take special precautions to insert or update null values in a database. Interaction with Java, including CFORM based hibernate could also result in returned null values so we always had te be very careful when trying to handle these dreaded nulls.

Lucee already has full null support since many years, but just as with the latest ACF version, you have to enable this in the administrator, just to stay compatible with older versions of ACF.

So, because of all these null handling issues, why not enable full null support? That’s what we imagined when creating our latest REST based application. But before hurrying to your admin panel better think if it will break something.

Before the Modernize or die times as promoted by Ortus Solutions there were many ways to find out in Coldbox if all input variables existed. Let me give these two JSON examples, both are used for the creation of a user in the body of a post request:

//first example, customer_id as a null value because customer is not selected yet
{
    "customer_id": null,
    "username": "wdb",
    "password": "topsecret"
}
//second example, customer_id omitted because customer is not selected yet
{
    "username": "wdb",
    "password": "topsecret"
}

When we post this userdata, I want to validate if my customer_id is there so I can populate some required customer field. When null support is not enabled we have a few options to check if we have a usable customer_id.

function createUser( event, rc, prc ) {
  //option 1
  if ( event.valueExists("customer_id") ){
    //....
  }
  //option 2
  if ( structKeyExists(rc,"customer_id") ){
    //....
  }
  //option 3
  if ( !isNull(rc.customer_id) ){
    //....
  }

The first options seems to make sense. Event.valueExists is a way to check if my customer_id is a value in my request collection.
The second options is slightly more low level, it just checks the request collection for the existence of customer_id.
The third option is a little bit more direct. It just checks if rc.customer_id is not null so I can continue.

So it seems it doesn’t matter which method I use. But now I enable full null support, and the whole landscape is changing. In the previous part I just assumed the key should be there, or not be null.

But now I have to know what my frontEnd VueJS developer is doing. Is he sending a null value for customer_id if there is no customer selection yet? Or is he only sending values in the JSON body which already have a value? This will make a lot of difference .

If my frondend developer is sending null values and I enable null support in CFML my event.valueExists and StructKeyExists() checks are completely useless, because my customer_id variable now does exist in the request collection. The problem here is it’s value is useless, because I can’t retrieve a required customer based on a null value. So the only safe check now is the !Isnull(rc.customer_id) .

The situation is still a bit different if you also want to be able to update a database based on the input of a null value. In that case you have to check for both Event.ValueExists AND IsNull.

The above examples seem quite trivial, but a word of warning is appropriate here. You really have to know how your frontend application should handle these null values. Are you validating ALL properties, or only the properties which have been entered by the user?

A second important point is the handling of nulls in some of your supporting libraries. We failed a lot of tests because one of our libraries tried to determine the datatype of our input automatically. Since null values have no datatype the library failed. This was fixed very soon, but especially when using some older libraries or modules you really should take a close look at the code when possible.

Order of elements in a qb array of structs

Recently someone asked in the coldbox Slack channel if the keys of a struct are always accessed in the same order. The answer is usually no , but if you know which keys are present it is quite simple to access them in the right order. But if you really want the keys in a fixed order you can create your structs this way:

MyOrderedStruct= structNew( "ordered"); 

Although the key order is seldom important we encountered such a case. We were building a control panel in VueJS where we displayed a list of DNS records based on a JSON array of structs.
These records can be exported to a comma delimited file, but since we were doing the export in some standard Vue component we were limited in the output format of the file. Keys showed up in the same order as in the JSON structs, which was undesirable for our clients.

Our output was based on a qb (QueryBuilder) query were the results were returned as an array of structs. Let’s say we were querying for id and name in our query, e.g:

return qb.from("records")
  .select("id,name")
  .get()
//wen serializing to json the result might look like this
//but we want id,name order instead of name,id
"data": [
      {
          "name": "SomeName",
          "id": "297A83FD-1715-416F-801B-44BE1743443A",
      },
      {
          "name": "Another item",
          "id": "892FECBC-84FA-4C5E-B494-525C3712F6A2"
      }
] 

If we want to change the order of the struct keys we could do some mapping on the array, e.q.

return items.map(function(item){
  var newitem = structNew( "ordered" );
  newitem.id = item.id;
  newitem.name = item.name;
  return newitem;
});

but this is quite inefficient for larger datasets. Qb is converting all queries to an array of structs, and we are creating structs again based on the qb results. Fortunately qb has a handy feature where you can define your own output format. In this case the queries in qb are directly converted to an array of ordered structs. The following code snippet was suggested by qb author Eric Peterson. Thanks Eric!

// CF2016+ and/or Lucee 5+
moduleSettings = {
    qb = {
        returnFormat = function( q ) {
            return queryReduce( arguments.q, function( acc, row ) {
                var rowStruct = structNew( "ordered" );
                for ( var columnName in q.columnList ) {
                    rowStruct[ columnName ] = row[ columnName ];
                }
                acc.append( rowStruct );
                return acc;
            }, [] );
        }
    }
}

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