dataparser-json.js revision 85d511965757454bd8f7dc3e987518eb06e78d8f
/**
* The DataParser utility provides a common configurable interface for widgets to
* parse a variety of data against a given schema.
*
* @module dataparser-json
* @requires json, dataparser-base
* @title DataParser JSON Submodule
*/
/**
* JSON subclass for the YUI DataParser utility.
* @class DataParser.JSON
* @extends DataParser.Base
* @constructor
*/
DPJSON = function() {
};
/////////////////////////////////////////////////////////////////////////////
//
// DataParser.JSON static properties
//
/////////////////////////////////////////////////////////////////////////////
/**
* Class name.
*
* @property DataParser.JSON.NAME
* @type String
* @static
* @final
* @value "DataParser.JSON"
*/
NAME: "DataParser.JSON",
/////////////////////////////////////////////////////////////////////////////
//
// DataSource.XHR Attributes
//
/////////////////////////////////////////////////////////////////////////////
ATTRS: {
/**
* @attribute schema
* @description Object literal schema definition:
<dl>
<dt>resultsList {String}</dt>
<dd>Pointer to array of tabular data</dd>
<dt>fields {String[] | Object []}</dt>
<dd>Array of field names (aka keys), or array of object literals such as:
{key:"fieldname", parser:Date.parse}</dd>
<dt>metaFields {Object}</dt>
<dd>Hash of field names (aka keys) to include in the
oParsedResponse.meta collection</dd>
</dl>
* @type Object
* @default {}
*/
schema: {
value: {}
}
},
/**
* Utility function converts JSON locator strings into walkable paths
*
* @method DataParser.JSON.buildPath
* @param locator {String} JSON value locator.
* @return {String[]} Walkable path to data value.
* @static
*/
var path = null,
keys = [],
i = 0;
if (locator) {
// Strip the ["string keys"] and [1] array indexes
replace(/\[(['"])(.*?)\1\]/g,
function (x,$1,$2) {keys[i]=$2;return '.@'+(i++);}).
replace(/\[(\d+)\]/g,
function (x,$1) {keys[i]=parseInt($1,10)|0;return '.@'+(i++);}).
replace(/^\./,''); // remove leading dot
// Validate against problematic characters.
if (!/[^\w\.\$@]/.test(locator)) {
path = locator.split('.');
for (i=path.length-1; i >= 0; --i) {
if (path[i].charAt(0) === '@') {
path[i] = keys[parseInt(path[i].substr(1),10)];
}
}
}
else {
}
}
return path;
},
/**
* Utility function to walk a path and return the value located there.
*
* @method DataParser.JSON.walkPath
* @param path {String[]} Locator path.
* @param data {String} Data to traverse.
* @return {Object} Data value at location.
* @static
*/
walkPath: function (path, data) {
var i = 0,
len = path.length;
for (;i<len;i++) {
data = data[path[i]];
}
return data;
}
});
Y.extend(DPJSON, Y.DataParser.Base, {
/**
* Overriding parse method traverses JSON data according to given schema.
*
* @method _parse
* @param e {Event.Facade} Custom Event Facade for <code>request</code> event.
* @param e.data {MIXED} Data to parse.
* @return TBD
* @protected
*/
_parse: function(data) {
var schema = this.get("schema"),
data_in = (data.responseText && Y.JSON.parse(data.responseText)) || data,
data_out = {results:[],meta:{}};
if(LANG.isObject(data_in) && schema) {
// Parse results data
data_out = this._parseResults(schema, data_in, data_out);
// Parse meta data
if(LANG.isObject(schema.metaFields)) {
data_out = this._parseMeta(schema.metaFields, data_in, data_out);
}
}
else {
data_out.error = true;
}
return data_out;
},
/**
* Schema-parse list of results from full data
*
* @method _parseResults
* @return TBD
* @protected
*/
_parseResults: function(schema, data_in, data_out) {
if(schema.resultsList) {
var bError = false,
results = [],
path;
path = DPJSON.buildPath(schema.resultsList);
if(path) {
results = DPJSON.walkPath(path, data_in);
if (results === undefined) {
bError = true;
}
else {
if(LANG.isArray(schema.fields)) {
if(LANG.isArray(schema.fields)) {
results = this._parseFields(schema.fields, results);
}
else {
bError = true;
}
}
}
}
else {
bError = true;
}
if (bError) {
data_out.error = true;
}
data_out.results = results;
}
return data_out;
},
/**
* Schema-parse field data out of list of full results
*
* @method _parseFields
* @return TBD
* @protected
*/
_parseFields: function(fields, results) {
var data_out = [],
len = fields.length,
i, j,
field, key, path, parser,
simplePaths = [], complexPaths = [], fieldParsers = [],
result, record;
// First collect hashes of simple paths, complex paths, and parsers
for (i=0; i<len; i++) {
field = fields[i]; // A field can be a simple string or a hash
key = field.key || field; // Find the key
// Validate and store locators for later
path = DPJSON.buildPath(key);
if (path) {
if (path.length === 1) {
simplePaths[simplePaths.length] = {key:key, path:path[0]};
} else {
complexPaths[complexPaths.length] = {key:key, path:path};
}
} else {
}
// Validate and store parsers for later
parser = (LANG.isFunction(field.parser)) ? field.parser : Y.DataParser[field.parser+''];
if (parser) {
fieldParsers[fieldParsers.length] = {key:key, parser:parser};
}
}
// Traverse list of results, creating records of simple fields,
// complex fields, and applying parsers as necessary
for (i=results.length-1; i>=0; --i) {
record = {};
result = results[i];
if(result) {
// Cycle through simpleLocators
for (j=simplePaths.length-1; j>=0; --j) {
// Bug 1777850: The result might be an array instead of object
record[simplePaths[j].key] =
LANG.isUndefined(result[simplePaths[j].path]) ?
result[j] : result[simplePaths[j].path];
}
// Cycle through complexLocators
for (j=complexPaths.length - 1; j>=0; --j) {
record[complexPaths[j].key] = DPJSON.walkPath(complexPaths[j].path, result);
}
// Cycle through fieldParsers
for (j=fieldParsers.length-1; j>=0; --j) {
key = fieldParsers[j].key;
record[key] = fieldParsers[j].parser(record[key]);
// Safety net
if (LANG.isUndefined(record[key])) {
record[key] = null;
}
}
}
data_out[i] = record;
}
return data_out;
},
/**
* Parses results data according to schema
*
* @method _parseResults
* @return TBD
* @protected
*/
_parseMeta: function(metaFields, data_in, data_out) {
var key, path;
for(key in metaFields) {
if (metaFields.hasOwnProperty(key)) {
path = DPJSON.buildPath(metaFields[key]);
if (path && data_in) {
data_out.meta[key] = DPJSON.walkPath(path, data_in);
}
}
}
return data_out;
}
});
Y.DataParser.JSON = DPJSON;