ColdFusion Query Json Custom Data Reader For ExtJS
Adobe's implementation of JSON return for ColdFusion is great, and frustrating. They use a non-standard return in that, instead of the expected name/value pairs, they return first a COLUMNS element, listing the column names only once, and then the DATA array of the record set values. The column names are listed in the order with which the data is listed in each array element. This is great, in the fact that the data packets are much smaller than the traditional return (traditional meaning, that which is returned by most other app servers), but the down side is, it isn't traditional.
John Wilson wrote a custom Data Reader for the Ext JS library, to help with parsing the ColdFusion return. However, although it created records within a Data Store, it didn't handle the column aliasing you are usually capable of when defining fields, nor did it properly cast variables as it should. I finally had a chance to run it through Firebug, and step through the process, at which point I also really had a chance to review the custom extension.
While it worked, it really wasn't using the best tool for the job. The extension extended the Ext.data.DataReader base component. The ColdFusion return basically gives you an Array of records (the DATA), and Ext JS already provides an Ext.data.ArrayReader object that extends the JsonReader. So, after some refactoring and general tinkering, I now release the CFQueryReader custom Ext data reader.
Inspired by the CFJsonReader, originally writtin by John Wilson (Daemach).
This Custom Data Reader will take the JSON return of a ColdFusion Query object, rather returned straight up, or via the ColdFusion QueryForGrid() method.
The CFQueryReader constructor takes two arguments @meta : object containing single key/value pair for the 'id' of each record, equating to the 'mapping' of the column @recordType : field mapping object
The recordType object allows you to alias the returned ColdFusion column name (which is always passed in upper case) to any 'name' you wish, as well as assign a data type, which your ExtJS app will attempt to cast whenever the value is referenced.
ColdFusion's JSON return, for a ColdFusion Query object, will appear in the following format:
"STREXPENSECATEGORIES"],"DATA" :[[2,"Carpet Cleaning",1,"Cleaining"],
[1,"Cleaning Service",1,"Cleaining"]]}
The ColdFusion JSON return on any query that is first passed through ColdFusion's QueryForGrid() method will return the object in the following format:
"DATA":[[1,"Bob","Smith"],[6,"Jim","Brown"]]}}
The Ext.data.CFQueryReader is designed to accomodate either format automatically. You would create your reader instance in much the same way as the CFJsonReader was created:
{name: 'myIdField', mapping: 'MYIDFIELD'},
{name: 'data1', mapping: 'DATA1'},
{name: 'data2', mapping: 'DATA2'}
];
var myCFReader = new Ext.data.CFQueryReader({id:'MYIDFIELD'},myDataModel);
Notice that the 'id' value mirrors the alias 'name' of the record's field.
The CFQueryReader is available from the below download link. Anyone having any issues just post a comment. You may also find information on the Ext JS Forum Post.
You know, I've never tried a composite key within this. The reader's "id" attribute is strictly to provide the store with a unique record identifier. For instance, I have a table for States where my primary key is actually the state's abbreviation [a CHAR(2) field], which is the "id" I give to the reader.