# DataField.js

    /**
     * @class Ext.data.Field
     * <p>This class encpasulates the field definition information specified in the field definition objects
     * passed to {@link Ext.data.Record#create}.</p>
     * <p>Developers do not need to instantiate this class. Instances are created by {@link Ext.data.Record.create}
     * and cached in the {@link Ext.data.Record#fields fields} property of the created Record constructor's <b>prototype.</b></p>
     */
    Ext.data.Field = function(config){
        if(typeof config == "string"){
            config = {name: config};
        }
        Ext.apply(this, config);

        if(!this.type){
            this.type = "auto";
        }

        var st = Ext.data.SortTypes;
        // named sortTypes are supported, here we look them up
        if(typeof this.sortType == "string"){
            this.sortType = st[this.sortType];
        }

        // set default sortType for strings and dates
        if(!this.sortType){
            switch(this.type){
                case "string":
                    this.sortType = st.asUCString;
                    break;
                case "date":
                    this.sortType = st.asDate;
                    break;
                default:
                    this.sortType = st.none;
            }
        }

        // define once
        var stripRe = /[\$,%]/g;

        // prebuilt conversion function for this field, instead of
        // switching every time we're reading a value
        if(!this.convert){
            var cv, dateFormat = this.dateFormat;
            switch(this.type){
                case "":
                case "auto":
                case undefined:
                    cv = function(v){ return v; };
                    break;
                case "string":
                    cv = function(v){ return (v === undefined || v === null) ? '' : String(v); };
                    break;
                case "int":
                    cv = function(v){
                        return v !== undefined && v !== null && v !== '' ?
                               parseInt(String(v).replace(stripRe, ""), 10) : '';
                        };
                    break;
                case "float":
                    cv = function(v){
                        return v !== undefined && v !== null && v !== '' ?
                               parseFloat(String(v).replace(stripRe, ""), 10) : '';
                        };
                    break;
                case "bool":
                case "boolean":
                    cv = function(v){ return v === true || v === "true" || v == 1; };
                    break;
                case "date":
                    cv = function(v){
                        if(!v){
                            return '';
                        }
                        if(Ext.isDate(v)){
                            return v;
                        }
                        if(dateFormat){
                            if(dateFormat == "timestamp"){
                                return new Date(v*1000);
                            }
                            if(dateFormat == "time"){
                                return new Date(parseInt(v, 10));
                            }
                            return Date.parseDate(v, dateFormat);
                        }
                        var parsed = Date.parse(v);
                        return parsed ? new Date(parsed) : null;
                    };
                 break;

            }
            this.convert = cv;
        }
    };

    Ext.data.Field.prototype = {
        /**
         * @cfg {String} name
         * The name by which the field is referenced within the Record. This is referenced by,
         * for example, the <em>dataIndex</em> property in column definition objects passed to {@link Ext.grid.ColumnModel}
         */
    // holder
    /***
         * @cfg {String} type
         * (Optional) The data type for conversion to displayable value. Possible values are
         * <div class="mdetail-params"><ul><li>auto (Default, implies no conversion)</li>
         * <li>string</li>
         * <li>int</li>
         * <li>float</li>
         * <li>boolean</li>
         * <li>date</li></ul></div>
         */
    // holder
    /***
         * @cfg {Function} convert
         * (Optional) A function which converts the value provided by the Reader into an object that will be stored
         * in the Record. It is passed the following parameters:<ul>
         * <li><b>v</b> : Mixed<div class="sub-desc">The data value as read by the Reader.</div></li>
         * <li><b>rec</b> : Mixed<div class="sub-desc">The data object containing the row as read by the Reader.
         * Depending on Reader type, this could be an Array, an object, or an XML element.</div></li>
         * </ul>
         */
    // holder
    /***
         * @cfg {String} dateFormat
         * (Optional) A format string for the {@link Date#parseDate Date.parseDate} function, or "timestamp" if the
         * value provided by the Reader is a UNIX timestamp, or "time" if the value provided by the Reader is a
         * javascript millisecond timestamp.
         */
        dateFormat: null,
        /**
         * @cfg {Mixed} defaultValue
         * (Optional) The default value used <b>when a Record is being created by a
         * {@link Ext.data.Reader Reader}</b> when the item referenced by the <b><tt>mapping</tt></b> does not exist in the data object
         * (i.e. undefined). (defaults to "")
         */
        defaultValue: "",
        /**
         * @cfg {String} mapping
         * (Optional) A path specification for use by the {@link Ext.data.Reader} implementation
         * that is creating the Record to access the data value from the data object. If an {@link Ext.data.JsonReader}
         * is being used, then this is a string containing the javascript expression to reference the data relative to
         * the Record item's root. If an {@link Ext.data.XmlReader} is being used, this is an {@link Ext.DomQuery} path
         * to the data item relative to the Record element. If the mapping expression is the same as the field name,
         * this may be omitted.
         */
        mapping: null,
        /**
         * @cfg {Function} sortType
         * (Optional) A function which converts a Field's value to a comparable value in order to ensure correct
         * sort ordering. Predefined functions are provided in {@link Ext.data.SortTypes}
         */
        sortType : null,
        /**
         * @cfg {String} sortDir
         * (Optional) Initial direction to sort. "ASC" or "DESC"
         */
        sortDir : "ASC"
    };

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