#

API Docs for: 3.10.3
Show: Inherited Protected Private Deprecated

# File: dataschema/js/dataschema-json.js

    /**
    Provides a DataSchema implementation which can be used to work with JSON data.

    @module dataschema
    @submodule dataschema-json
    **/

    /**
    Provides a DataSchema implementation which can be used to work with JSON data.

    See the `apply` method for usage.

    @class DataSchema.JSON
    @extends DataSchema.Base
    @static
    **/
    var LANG = Y.Lang,
        isFunction = LANG.isFunction,
        isObject   = LANG.isObject,
        isArray    = LANG.isArray,
        // TODO: I don't think the calls to Base.* need to be done via Base since
        // Base is mixed into SchemaJSON.  Investigate for later.
        Base       = Y.DataSchema.Base,

        SchemaJSON;

    SchemaJSON = {

    /////////////////////////////////////////////////////////////////////////////
    //
    // DataSchema.JSON static methods
    //
    /////////////////////////////////////////////////////////////////////////////
        /**
         * Utility function converts JSON locator strings into walkable paths
         *
         * @method getPath
         * @param locator {String} JSON value locator.
         * @return {String[]} Walkable path to data value.
         * @static
         */
        getPath: function(locator) {
            var path = null,
                keys = [],
                i = 0;

            if (locator) {
                // Strip the ["string keys"] and [1] array indexes
                // TODO: the first two steps can probably be reduced to one with
                // /\[\s*(['"])?(.*?)\1\s*\]/g, but the array indices would be
                // stored as strings.  This is not likely an issue.
                locator = locator.
                    replace(/\[\s*(['"])(.*?)\1\s*\]/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.
                // commented out because the path isn't sent to eval, so it
                // should be safe. I'm not sure what makes a locator invalid.
                //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 {
                    Y.log("Invalid locator: " + locator, "error", "dataschema-json");
                }
                */
            }
            return path;
        },

        /**
         * Utility function to walk a path and return the value located there.
         *
         * @method getLocationValue
         * @param path {String[]} Locator path.
         * @param data {String} Data to traverse.
         * @return {Object} Data value at location.
         * @static
         */
        getLocationValue: function (path, data) {
            var i = 0,
                len = path.length;
            for (;i<len;i++) {
                if (isObject(data) && (path[i] in data)) {
                    data = data[path[i]];
                } else {
                    data = undefined;
                    break;
                }
            }
            return data;
        },

        /**
        Applies a schema to an array of data located in a JSON structure, returning
        a normalized object with results in the `results` property. Additional
        information can be parsed out of the JSON for inclusion in the `meta`
        property of the response object.  If an error is encountered during
        processing, an `error` property will be added.

        The input _data_ is expected to be an object or array.  If it is a string,
        it will be passed through `Y.JSON.parse()`.

        If _data_ contains an array of data records to normalize, specify the
        _schema.resultListLocator_ as a dot separated path string just as you would
        reference it in JavaScript.  So if your _data_ object has a record array at
        _data.response.results_, use _schema.resultListLocator_ =
        "response.results". Bracket notation can also be used for array indices or
        object properties (e.g. "response['results']");  This is called a "path
        locator"

        Field data in the result list is extracted with field identifiers in
        _schema.resultFields_.  Field identifiers are objects with the following
        properties:

          * `key`   : <strong>(required)</strong> The path locator (String)
          * `parser`: A function or the name of a function on `Y.Parsers` used
                to convert the input value into a normalized type.  Parser
                functions are passed the value as input and are expected to
                return a value.

        If no value parsing is needed, you can use path locators (strings)
        instead of field identifiers (objects) -- see example below.

        If no processing of the result list array is needed, _schema.resultFields_
        can be omitted; the `response.results` will point directly to the array.

        If the result list contains arrays, `response.results` will contain an
        array of objects with key:value pairs assuming the fields in
        _schema.resultFields_ are ordered in accordance with the data array
        values.

        If the result list contains objects, the identified _schema.resultFields_
        will be used to extract a value from those objects for the output result.

        To extract additional information from the JSON, include an array of
        path locators in _schema.metaFields_.  The collected values will be
        stored in `response.meta`.

        @example
            // Process array of arrays
            var schema = {
                    resultListLocator: 'produce.fruit',
                    resultFields: [ 'name', 'color' ]
                },
                data = {
                    produce: {
                        fruit: [
                            [ 'Banana', 'yellow' ],
                            [ 'Orange', 'orange' ],
                            [ 'Eggplant', 'purple' ]
                        ]
                    }
                };

            var response = Y.DataSchema.JSON.apply(schema, data);

            // response.results[0] is { name: "Banana", color: "yellow" }

            // Process array of objects + some metadata
            schema.metaFields = [ 'lastInventory' ];

            data = {
                produce: {
                    fruit: [
                        { name: 'Banana', color: 'yellow', price: '1.96' },
                        { name: 'Orange', color: 'orange', price: '2.04' },
                        { name: 'Eggplant', color: 'purple', price: '4.31' }
                    ]
                },
                lastInventory: '2011-07-19'
            };

            response = Y.DataSchema.JSON.apply(schema, data);

            // response.results[0] is { name: "Banana", color: "yellow" }
            // response.meta.lastInventory is '2001-07-19'

            // Use parsers
            schema.resultFields = [
                {
                    key: 'name',
                    parser: function (val) { return val.toUpperCase(); }
                },
                {
                    key: 'price',
                    parser: 'number' // Uses Y.Parsers.number
                }
            ];

            response = Y.DataSchema.JSON.apply(schema, data);

            // Note price was converted from a numeric string to a number
            // response.results[0] looks like { fruit: "BANANA", price: 1.96 }

        @method apply
        @param {Object} [schema] Schema to apply.  Supported configuration
            properties are:
          @param {String} [schema.resultListLocator] Path locator for the
              location of the array of records to flatten into `response.results`
          @param {Array} [schema.resultFields] Field identifiers to
              locate/assign values in the response records. See above for
              details.
          @param {Array} [schema.metaFields] Path locators to extract extra
              non-record related information from the data object.
        @param {Object|Array|String} data JSON data or its string serialization.
        @return {Object} An Object with properties `results` and `meta`
        @static
        **/
        apply: function(schema, data) {
            var data_in = data,
                data_out = { results: [], meta: {} };

            // Convert incoming JSON strings
            if (!isObject(data)) {
                try {
                    data_in = Y.JSON.parse(data);
                }
                catch(e) {
                    data_out.error = e;
                    return data_out;
                }
            }

            if (isObject(data_in) && schema) {
                // Parse results data
                data_out = SchemaJSON._parseResults.call(this, schema, data_in, data_out);

                // Parse meta data
                if (schema.metaFields !== undefined) {
                    data_out = SchemaJSON._parseMeta(schema.metaFields, data_in, data_out);
                }
            }
            else {
                Y.log("JSON data could not be schema-parsed: " + Y.dump(data) + " " + Y.dump(data), "error", "dataschema-json");
                data_out.error = new Error("JSON schema parse failure");
            }

            return data_out;
        },

        /**
         * Schema-parsed list of results from full data
         *
         * @method _parseResults
         * @param schema {Object} Schema to parse against.
         * @param json_in {Object} JSON to parse.
         * @param data_out {Object} In-progress parsed data to update.
         * @return {Object} Parsed data object.
         * @static
         * @protected
         */
        _parseResults: function(schema, json_in, data_out) {
            var getPath  = SchemaJSON.getPath,
                getValue = SchemaJSON.getLocationValue,
                path     = getPath(schema.resultListLocator),
                results  = path ?
                            (getValue(path, json_in) ||
                             // Fall back to treat resultListLocator as a simple key
                                json_in[schema.resultListLocator]) :
                            // Or if no resultListLocator is supplied, use the input
                            json_in;

            if (isArray(results)) {
                // if no result fields are passed in, then just take
                // the results array whole-hog Sometimes you're getting
                // an array of strings, or want the whole object, so
                // resultFields don't make sense.
                if (isArray(schema.resultFields)) {
                    data_out = SchemaJSON._getFieldValues.call(this, schema.resultFields, results, data_out);
                } else {
                    data_out.results = results;
                }
            } else if (schema.resultListLocator) {
                data_out.results = [];
                data_out.error = new Error("JSON results retrieval failure");
                Y.log("JSON data could not be parsed: " + Y.dump(json_in), "error", "dataschema-json");
            }

            return data_out;
        },

        /**
         * Get field data values out of list of full results
         *
         * @method _getFieldValues
         * @param fields {Array} Fields to find.
         * @param array_in {Array} Results to parse.
         * @param data_out {Object} In-progress parsed data to update.
         * @return {Object} Parsed data object.
         * @static
         * @protected
         */
        _getFieldValues: function(fields, array_in, data_out) {
            var results = [],
                len = fields.length,
                i, j,
                field, key, locator, path, parser, val,
                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
                locator = field.locator || key; // Find the locator

                // Validate and store locators for later
                path = SchemaJSON.getPath(locator);
                if (path) {
                    if (path.length === 1) {
                        simplePaths.push({
                            key : key,
                            path: path[0]
                        });
                    } else {
                        complexPaths.push({
                            key    : key,
                            path   : path,
                            locator: locator
                        });
                    }
                } else {
                    Y.log("Invalid key syntax: " + key, "warn", "dataschema-json");
                }

                // Validate and store parsers for later
                //TODO: use Y.DataSchema.parse?
                parser = (isFunction(field.parser)) ?
                            field.parser :
                            Y.Parsers[field.parser + ''];

                if (parser) {
                    fieldParsers.push({
                        key   : key,
                        parser: parser
                    });
                }
            }

            // Traverse list of array_in, creating records of simple fields,
            // complex fields, and applying parsers as necessary
            for (i=array_in.length-1; i>=0; --i) {
                record = {};
                result = array_in[i];
                if(result) {
                    // Cycle through complexLocators
                    for (j=complexPaths.length - 1; j>=0; --j) {
                        path = complexPaths[j];
                        val = SchemaJSON.getLocationValue(path.path, result);
                        if (val === undefined) {
                            val = SchemaJSON.getLocationValue([path.locator], result);
                            // Fail over keys like "foo.bar" from nested parsing
                            // to single token parsing if a value is found in
                            // results["foo.bar"]
                            if (val !== undefined) {
                                simplePaths.push({
                                    key:  path.key,
                                    path: path.locator
                                });
                                // Don't try to process the path as complex
                                // for further results
                                complexPaths.splice(i,1);
                                continue;
                            }
                        }

                        record[path.key] = Base.parse.call(this,
                            (SchemaJSON.getLocationValue(path.path, result)), path);
                    }

                    // Cycle through simpleLocators
                    for (j = simplePaths.length - 1; j >= 0; --j) {
                        path = simplePaths[j];
                        // Bug 1777850: The result might be an array instead of object
                        record[path.key] = Base.parse.call(this,
                                ((result[path.path] === undefined) ?
                                result[j] : result[path.path]), path);
                    }

                    // Cycle through fieldParsers
                    for (j=fieldParsers.length-1; j>=0; --j) {
                        key = fieldParsers[j].key;
                        record[key] = fieldParsers[j].parser.call(this, record[key]);
                        // Safety net
                        if (record[key] === undefined) {
                            record[key] = null;
                        }
                    }
                    results[i] = record;
                }
            }
            data_out.results = results;
            return data_out;
        },

        /**
         * Parses results data according to schema
         *
         * @method _parseMeta
         * @param metaFields {Object} Metafields definitions.
         * @param json_in {Object} JSON to parse.
         * @param data_out {Object} In-progress parsed data to update.
         * @return {Object} Schema-parsed meta data.
         * @static
         * @protected
         */
        _parseMeta: function(metaFields, json_in, data_out) {
            if (isObject(metaFields)) {
                var key, path;
                for(key in metaFields) {
                    if (metaFields.hasOwnProperty(key)) {
                        path = SchemaJSON.getPath(metaFields[key]);
                        if (path && json_in) {
                            data_out.meta[key] = SchemaJSON.getLocationValue(path, json_in);
                        }
                    }
                }
            }
            else {
                data_out.error = new Error("JSON meta data retrieval failure");
            }
            return data_out;
        }
    };

    // TODO: Y.Object + mix() might be better here
    Y.DataSchema.JSON = Y.mix(SchemaJSON, Base);