How to ignore null fields in ExtJS data models?

Question

How to ignore null fields in ExtJS data models?

My question is very long ... So be patient :)

I work with models in ExtJS 4, but I have some problems with associations, so I created a function to automatically create a model for me. Suppose I need to parse the following JSON:

{ 
    "success": true, 
    "total": 28, 
    "itens": [{
        "id":1,
        "nome":"ACRE",
        "sigla":"AC",
        "pais":{
            "id":31,
            "nome":"BRASIL",
            "sigla":"BR"
        }
    },{
        "id":2,
        "nome":"ALAGOAS",
        "sigla":"AL",
        "pais":{
            "id":31,
            "nome":"BRASIL",
            "sigla":"BR"
        }
    }, ...]
}

Eden represent the provinces (Estados in Brazilian Portuguese) that have a country (País in Brazilian Portuguese). I tried to use ExtJS associations, but I thought it worked like a Java relationship, and I was wrong. Well, for this JSON, I have these Java classes and these Ext-models (models are created using the provided function).

Pais.java

@Entity
// named queries here...
public class Pais implements Serializable {

    @Id
    @GeneratedValue
    private Long id;

    @NotNull
    @NotEmpty
    @Length( max = 100 )
    private String nome;

    @NotNull
    @NotEmpty
    @Column( unique = true )
    @Length( min = 2, max = 4 )
    private String sigla;

    // getters, setters, equals, hashCode and toString here

}

Estado.java

@Entity
// named queries here...
public class Estado implements Serializable {

    @Id
    @GeneratedValue
    private Long id;

    @NotNull
    @NotEmpty
    @Length( max = 100 )
    private String nome;

    @NotNull
    @NotEmpty
    @Column( unique = true )
    @Length( min = 2, max = 4 )
    private String sigla;

    @NotNull
    @ManyToOne
    private Pais pais;

    // getters, setters, equals, hashCode and toString here

}

Model Creation Function

Ext.ns( "Uteis" );

// other utility functions here...

Uteis.createModel = function( modelData ) {

    var fields = modelData.fields;
    var processedFields = [];
    var normalFields = [];
    var relationFields = [];

    for ( var i in fields ) {

        if ( fields[i].type ) {

            switch ( fields[i].type ) {

                case "auto":
                case "string":
                case "int":
                case "float":
                case "boolean":
                case "date":
                    normalFields.push( fields[i] );
                    break;

                default:

                    var relationField = fields[i];

                    var prefix = relationField.name + ".";
                    var modelInstance = Ext.create( relationField.type );

                    modelInstance.fields.each( function( item, index, length ) {

                        var newField = {};

                        // I used this sintax to make possible create only some fields
                        // if I need in the future.
                        newField["name"] = prefix + item.name;
                        newField["type"] = item.type.type;

                        newField["convert"] = item.convert;
                        newField["dateFormat"] = item.dateFormat;
                        newField["defaultValue"] = item.defaultValue;
                        newField["mapping"] = item.mapping;
                        newField["persist"] = item.persist;
                        newField["sortDir"] = item.sortDir;
                        newField["sortType"] = item.sortType;
                        newField["useNull"] = item.useNull;

                        relationFields.push( newField );

                    });

                    break;

            }

        } else {
            normalFields.push( fields[i] );
        }

    }

    processedFields = normalFields.concat( relationFields );

    // debugging code
    /*console.log( "*** " + modelData.name );
    for ( var i in processedFields ) {
        console.log( processedFields[i] );
    }*/

    Ext.define( modelData.name, {
        extend: "Ext.data.Model",
        fields: processedFields
    });

};

Using the function to create models

Uteis.createModel({ 
    name: "Modelos.Pais",
    fields: [
        { name: "id",  type: "int" },
        { name: "nome",  type: "string" },
        { name: "sigla",  type: "string" }
    ]
});

Uteis.createModel({ 
    name: "Modelos.Estado",
    fields: [
        { name: "id",  type: "int" },
        { name: "nome",  type: "string" },
        { name: "sigla",  type: "string" },
        { name: "pais", type: "Modelos.Pais" } // <= references the model created above
    ]
});

. ( , ).

Ext.define( "Modelos.Pais", {
    extend: "Ext.data.Model",
    fields: [
        { name: "id",  type: "int" },
        { name: "nome",  type: "string" },
        { name: "sigla",  type: "string" }
    ]
});

Ext.define( "Modelos.Estado", {
    extend: "Ext.data.Model",
    fields: [
        { name: "id",  type: "int" },
        { name: "nome",  type: "string" },
        { name: "sigla",  type: "string" },
        { name: "pais.id",  type: "int" },
        { name: "pais.nome",  type: "string" },
        { name: "pais.sigla",  type: "string" }
    ]
});

, ( createModel) JsonStores. Java , . , , . , , ( , , ). Gson JSON . , , undefined , , , ( ), Ext . Gson:

Gson gson = new GsonBuilder().serializeNulls().create();

, JSON , Ext . defaultValue . , Estados Países (Privinces and Countries), Pais @NotNull. JSON pais :

{ 
    "success": true, 
    "total": 28, 
    "itens": [{
        "id":1,
        "nome":"ACRE",
        "sigla":"AC",
        "pais":null   // <= here
    },{
        "id":2,
        "nome":"ALAGOAS",
        "sigla":"AL",
        "pais":{  // this is not null
            "id":31,
            "nome":"BRASIL",
            "sigla":"BR"
        }
    }, ...]
}

pais.id, pais.nome pais.sigla , pais null. , : , undefined? ... !

. , 15 , ... " ", Gson , . , JSON . :

/**
 * A method to traverse the object tree and set "default" values to null fields.
 * 
 * @param target The object to be inspected.
 */
public static void traverseAndSetDefaultValue( Object target ) {

    try {

        for ( Field f : target.getClass().getDeclaredFields() ) {

            // ok to change...
            f.setAccessible( true );

            // is null? so create something
            if ( f.get( target ) == null ) {

                // new instance of the current field
                Object newInstance = null;

                // it needs to traverse to the next level?
                boolean okToTraverse = false;

                switch ( f.getType().getSimpleName() ) {

                    case "Byte":
                    case "Short":
                    case "Integer":
                        newInstance = 0;
                        break;

                    case "Long":
                        newInstance = 0L;
                        break;

                    case "Float":
                        newInstance = 0F;
                        break;

                    case "Double":
                        newInstance = 0D;
                        break;

                    case "Character":
                        newInstance = '\0';
                        break;

                    case "Boolean":
                        newInstance = Boolean.FALSE;
                        break;

                    case "String":
                        newInstance = "";
                        break;

                    case "List":
                        newInstance = new ArrayList();
                        break;

                    case "Set":
                        newInstance = new HashSet();
                        break;

                    default:
                        // calling the default constructor for no 
                        // "default" types
                        newInstance = f.getType().newInstance();
                        okToTraverse = true;
                        break;

                }

                f.set( target, newInstance );

                if ( okToTraverse ) {
                    traverseAndSetDefaultValue( newInstance );
                }

            }

        }

    } catch ( IllegalAccessException | InstantiationException exc ) {
        exc.printStackTrace();
    }

}

, ... !

2: . !:) , . , . , ( , ). , . , , . !

+5

javascript extjs extjs4.1 models

davidbuzatto 12 . '12 20:38

2

Austin Greco · Answer 1 · 2012-08-31T19:16:00+0000

, , ; , :

Ext.define( "Modelos.Estado", {
    extend: "Ext.data.Model",
    fields: [
        { name: "id",  type: "int" },
        { name: "nome",  type: "string" },
        { name: "sigla",  type: "string" },
        { name: "pais.id",  type: "int", mapping: function( o ) { return o.pais ? o.pais.id : null; } },
        { name: "pais.nome",  type: "string", mapping: function( o ) { return o.pais ? o.pais.nome : null; } },
        { name: "pais.sigla",  type: "string", mapping: function( o ) { return o.pais ? o.pais.sigla : null; } }
    ]
});

Dmitry Shost · Answer 2 · 2012-10-15T14:39:33+0000

Ext.data.reader.Json, :

Ext.define('Ext.data.reader.SafeJson', {
    extend: 'Ext.data.reader.Json',
    alias : 'reader.safejson',
    /**
     * @private
     * Returns an accessor function for the given property string. Gives support for properties such as the following:
     * 'someProperty'
     * 'some.property'
     * 'some["property"]'
     * This is used by buildExtractors to create optimized extractor functions when casting raw data into model instances.
     */
    createAccessor: (function() {
        var re = /[\[\.]/;

        return function(expr) {
            if (Ext.isEmpty(expr)) {
                return Ext.emptyFn;
            }
            if (Ext.isFunction(expr)) {
                return expr;
            }
            if (this.useSimpleAccessors !== true) {
                var i = String(expr).search(re);
                if (i >= 0) {
                    if (i > 0) {    // Check all property chain for existence. Return null if any level does not exist.
                        var a = [];
                        var l = expr.split('.');
                        var r = '';
                        for (var w in l) {
                            r = r + '.' + l[w];
                            a.push('obj' + r);
                        }
                        var v = "(" + a.join(" && ") + ") ? obj." + expr + " : null";
                        return Ext.functionFactory('obj', 'return (' + v + ')');
                    } else {
                        return Ext.functionFactory('obj', 'return obj' + (i > 0 ? '.' : '') + expr);
                    }
                }
            }
            return function(obj) {
                return obj[expr];
            };
        };
    }()),

        /**
     * @private
     * @method
     * Returns an accessor expression for the passed Field. Gives support for properties such as the following:
     *
     * - 'someProperty'
     * - 'some.property'
     * - 'some["property"]'
     *
     * This is used by buildExtractors to create optimized on extractor function which converts raw data into model instances.
     */
    createFieldAccessExpression: (function() {
        var re = /[\[\.]/;

        return function(field, fieldVarName, dataName) {
            var me     = this,
                hasMap = (field.mapping !== null),
                map    = hasMap ? field.mapping : field.name,
                result,
                operatorSearch;

            if (typeof map === 'function') {
                result = fieldVarName + '.mapping(' + dataName + ', this)';
            } else if (this.useSimpleAccessors === true || ((operatorSearch = String(map).search(re)) < 0)) {
                if (!hasMap || isNaN(map)) {
                    // If we don't provide a mapping, we may have a field name that is numeric
                    map = '"' + map + '"';
                }
                result = dataName + "[" + map + "]";
            } else {                
                if (operatorSearch > 0) {
                    var a = [];
                    var l = map.split('.');
                    var r = '';
                    for (var w in l) {
                        r = r + '.' + l[w];
                        a.push(dataName + r);
                    }
                    result = "("+a.join(" && ")+") ? "+dataName+"."+map+" : null";
                } else {
                    result = dataName + map;
                }
            }            
            return result;
        };
    }())
});

, JSON- .

JSON:

{
    root: [{
        id: 1,
        name: {
            name: "John",
            phone: "123"
        },          
    },
    {
        id: 4,
        name: null,         
    },
    ]
}

: http://jsfiddle.net/8Ftag/

ExtJS 4.1.1

How to ignore null fields in ExtJS data models?

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