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# Example: DataSchema.JSON

DataSchema.JSON normalizes arbitrary JSON data against a given schema into an object with known properties.

#### Basic example

###### Data

    {
        "total":10,
        "results":[
            {"n":1, "fname":"George", "lname":"Washington"},
            {"n":2, "fname":"John", "lname":"Adams"},
            {"n":3, "fname":"Thomas", "lname":"Jefferson"},
            {"n":4, "fname":"James", "lname":"Madison"},
            {"n":5, "fname":"James", "lname":"Monroe"},
            {"n":6, "fname":"John", "mname":"Quincy", "lname":"Adams"},
            {"n":7, "fname":"Andrew", "lname":"Jackson"},
            {"n":8, "fname":"Martin", "lname":"Van Buren"},
            {"n":9, "fname":"William", "mname":"Henry", "lname":"Harrison"},
            {"n":10, "fname":"John", "lname":"Tyler"}
        ]
    }

###### Schema

    {
        metaFields: {total:"total"},
        resultListLocator: "results",
        resultFields: [{key:"n"}, {key:"fname"}, {key:"lname"}]
    }

###### Normalized data

#### Complex example

###### Data

    {
        "profile":{
            "current":160,
            "target":150
        },
        "reference": [
            {
                "category":"exercise",
                "type":"expenditure",
                "activities":[
                    {"name":"biking", "calories":550},
                    {"name":"golf", "calories":1000},
                    {"name":"running", "calories":650},
                    {"name":"swimming", "calories":650},
                    {"name":"walking", "calories":225}
                ]
            },
            {
                "category":"nutrition",
                "type":"intake",
                "fruit":[
                    {"name":"apple", "calories":70},
                    {"name":"banana", "calories":70},
                    {"name":"orange", "calories":90},
                ],
                "vegetables":[
                    {"name":"baked potato", "calories":150},
                    {"name":"broccoli", "calories":50},
                    {"name":"green beans", "calories":30}
                ]
            }
        ],
        "program": [
            {
                "category":"exercise",
                "schedule":[
                    {"day":"sunday", "activity":"swimming"},
                    {"day":"monday", "activity":"running"},
                    {"day":"tuesday", "activity":"biking"},
                    {"day":"wednesday", "activity":"running"},
                    {"day":"thursday", "activity":"swimming"},
                    {"day":"friday", "activity":"running"},
                    {"day":"saturday", "activity":"golf"}
                ]
            },
            {
                "category":"diet",
                "schedule":[
                ]
            }
        ]
    }

###### Schema

    {
        metaFields: {current:"profile.current", target:"profile.target",
            reference:"reference[0].activities"},
        resultListLocator: "program[0].schedule",
        resultFields: [{key:"day"}, {key:"activity"}]
    }

###### Normalized data

In order to use DataSchema.JSON, input data must be a JavaScript object.

    YUI().use("dataschema-json", function(Y) {
        var data_in = {
                total:10,
                results:[
                    {n:1, fname:"George", lname:"Washington"},
                    {n:2, fname:"John", lname:"Adams"},
                    {n:3, fname:"Thomas", lname:"Jefferson"},
                    {n:4, fname:"James", lname:"Madison"},
                    {n:5, fname:"James", lname:"Monroe"},
                    {n:6, fname:"John", mname:"Quincy", lname:"Adams"},
                    {n:7, fname:"Andrew", lname:"Jackson"},
                    {n:8, fname:"Martin", lname:"Van Buren"},
                    {n:9, fname:"William", mName:"Henry", lname:"Harrison"},
                    {n:10, fname:"John", lname:"Tyler"}
                ]
            },
            schema = {
                metaFields: {total:"total"},
                resultListLocator: "results",
                // Or simply: ["n", "fname", "lname"]
                resultFields: [{key:"n"}, {key:"fname"}, {key:"lname"}]
            },
            data_out = Y.DataSchema.JSON.apply(schema, data_in));

        alert(data_out);
    });

The data itself can get fairly complex, with deeply nested arrays and objects. In your schema, you can use dot notation and the array-index syntax to define these locations. When necessary, you can also use object-bracket notation to define locations that might otherwise be invalid with dot notation.

    YUI().use("dataschema-json", function(Y) {
            var data_in = {
                "profile":{
                    "current":160,
                    "target":150
                },
                "reference": [
                    {
                        "category":"exercise",
                        "type":"expenditure",
                        "activities":[
                            {"name":"biking", "calories":550},
                            {"name":"golf", "calories":1000},
                            {"name":"running", "calories":650},
                            {"name":"swimming", "calories":650},
                            {"name":"walking", "calories":225}
                        ]
                    },
                    {
                        "category":"nutrition",
                        "type":"intake",
                        "fruit":[
                            {"name":"apple", "calories":70},
                            {"name":"banana", "calories":70},
                            {"name":"orange", "calories":90},
                        ],
                        "vegetables":[
                            {"name":"baked potato", "calories":150},
                            {"name":"broccoli", "calories":50},
                            {"name":"green beans", "calories":30}
                        ]
                    }
                ],
                "program": [
                    {
                        "category":"exercise",
                        "weekly schedule":[
                            {"day":"sunday", "activity":"swimming"},
                            {"day":"monday", "activity":"running"},
                            {"day":"tuesday", "activity":"biking"},
                            {"day":"wednesday", "activity":"running"},
                            {"day":"thursday", "activity":"swimming"},
                            {"day":"friday", "activity":"running"},
                            {"day":"saturday", "activity":"golf"}
                        ]
                    },
                    {
                        "category":"diet",
                        "schedule":[
                        ]
                    }
                ]
            },
            schema = {
                metaFields: {current:"profile.current", target:"profile.target",
                    reference:"reference[0].activities"},
                resultListLocator: "program[0]['weekly schedule']",
                // Or simply: ["day", "activity"]
                resultFields: [{key:"day"}, {key:"activity"}]
            },
            data_out = Y.DataSchema.Array.apply(schema, data_in));

        alert(data_out);
    });