Fields are used to define what a Model is. They aren't instantiated directly - instead, when we create a class + * that extends {@link Ext.data.Model}, it will automatically create a Field instance for each field configured in a + * {@link Ext.data.Model Model}. For example, we might set up a model like this:
+ * +
+Ext.define('User', {
+ extend: 'Ext.data.Model',
+ fields: [
+ 'name', 'email',
+ {name: 'age', type: 'int'},
+ {name: 'gender', type: 'string', defaultValue: 'Unknown'}
+ ]
+});
+Four fields will have been created for the User Model - name, email, age and gender. Note that we specified a + * couple of different formats here; if we only pass in the string name of the field (as with name and email), the + * field is set up with the 'auto' type. It's as if we'd done this instead:
+ * +
+Ext.define('User', {
+ extend: 'Ext.data.Model',
+ fields: [
+ {name: 'name', type: 'auto'},
+ {name: 'email', type: 'auto'},
+ {name: 'age', type: 'int'},
+ {name: 'gender', type: 'string', defaultValue: 'Unknown'}
+ ]
+});
+Types and conversion
+ * + *The {@link #type} is important - it's used to automatically convert data passed to the field into the correct + * format. In our example above, the name and email fields used the 'auto' type and will just accept anything that is + * passed into them. The 'age' field had an 'int' type however, so if we passed 25.4 this would be rounded to 25.
+ * + *Sometimes a simple type isn't enough, or we want to perform some processing when we load a Field's data. We can + * do this using a {@link #convert} function. Here, we're going to create a new field based on another:
+ * +
+Ext.define('User', {
+ extend: 'Ext.data.Model',
+ fields: [
+ 'name', 'email',
+ {name: 'age', type: 'int'},
+ {name: 'gender', type: 'string', defaultValue: 'Unknown'},
+
+ {
+ name: 'firstName',
+ convert: function(value, record) {
+ var fullName = record.get('name'),
+ splits = fullName.split(" "),
+ firstName = splits[0];
+
+ return firstName;
+ }
+ }
+ ]
+});
+Now when we create a new User, the firstName is populated automatically based on the name:
+ * +
+var ed = Ext.ModelManager.create({name: 'Ed Spencer'}, 'User');
+
+console.log(ed.get('firstName')); //logs 'Ed', based on our convert function
+In fact, if we log out all of the data inside ed, we'll see this:
+ * +
+console.log(ed.data);
+
+//outputs this:
+{
+ age: 0,
+ email: "",
+ firstName: "Ed",
+ gender: "Unknown",
+ name: "Ed Spencer"
+}
+The age field has been given a default of zero because we made it an int type. As an auto field, email has + * defaulted to an empty string. When we registered the User model we set gender's {@link #defaultValue} to 'Unknown' + * so we see that now. Let's correct that and satisfy ourselves that the types work as we expect:
+ * +
+ed.set('gender', 'Male');
+ed.get('gender'); //returns 'Male'
+
+ed.set('age', 25.4);
+ed.get('age'); //returns 25 - we wanted an int, not a float, so no decimal places allowed
+dataIndex property in column definition objects passed to {@link Ext.grid.property.HeaderContainer}.
+ * Note: In the simplest case, if no properties other than name are required, a field
+ * definition may consist of just a String for the field name.
{@link Ext.data.Field#convert convert}
+ * has not been specified. This may be specified as a string value. Possible values are
+ * This may also be specified by referencing a member of the {@link Ext.data.Types} class.
+ *Developers may create their own application-specific data types by defining new members of the + * {@link Ext.data.Types} class.
+ */ + + /** + * @cfg {Function} convert + * (Optional) A function which converts the value provided by the Reader into an object that will be stored + * in the Model. It is passed the following parameters:{@link Ext.data.Field#defaultValue defaultValue}.
+// example of convert function
+function fullName(v, record){
+ return record.name.last + ', ' + record.name.first;
+}
+
+function location(v, record){
+ return !record.city ? '' : (record.city + ', ' + record.state);
+}
+
+Ext.define('Dude', {
+ extend: 'Ext.data.Model',
+ fields: [
+ {name: 'fullname', convert: fullName},
+ {name: 'firstname', mapping: 'name.first'},
+ {name: 'lastname', mapping: 'name.last'},
+ {name: 'city', defaultValue: 'homeless'},
+ 'state',
+ {name: 'location', convert: location}
+ ]
+});
+
+// create the data store
+var store = new Ext.data.Store({
+ reader: {
+ type: 'json',
+ model: 'Dude',
+ idProperty: 'key',
+ root: 'daRoot',
+ totalProperty: 'total'
+ }
+});
+
+var myData = [
+ { key: 1,
+ name: { first: 'Fat', last: 'Albert' }
+ // notice no city, state provided in data object
+ },
+ { key: 2,
+ name: { first: 'Barney', last: 'Rubble' },
+ city: 'Bedrock', state: 'Stoneridge'
+ },
+ { key: 3,
+ name: { first: 'Cliff', last: 'Claven' },
+ city: 'Boston', state: 'MA'
+ }
+];
+ * (Optional) Used when converting received data into a Date when the {@link #type} is specified as "date".
A format string for the {@link Ext.Date#parse Ext.Date.parse} 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. See {@link Date}
+ */ + dateFormat: null, + + /** + * @cfg {Boolean} useNull + *(Optional) Use when converting received data into a Number type (either int or float). If the value cannot be parsed,
+ * null will be used if useNull is true, otherwise the value will be 0. Defaults to false
+ */
+ useNull: false,
+
+ /**
+ * @cfg {Mixed} defaultValue
+ * (Optional) The default value used when a Model is being created by a {@link Ext.data.reader.Reader Reader}
+ * when the item referenced by the {@link Ext.data.Field#mapping mapping} does not exist in the data
+ * object (i.e. undefined). (defaults to "")
+ */
+ defaultValue: "",
+ /**
+ * @cfg {String/Number} mapping
+ *
(Optional) A path expression for use by the {@link Ext.data.reader.Reader} implementation + * that is creating the {@link Ext.data.Model Model} to extract the Field value from the data object. + * If the path expression is the same as the field name, the mapping may be omitted.
+ *The form of the mapping expression depends on the Reader being used.
+ *If a more complex value extraction strategy is required, then configure the Field with a {@link #convert} + * function. This is passed the whole row object, and may interrogate it in whatever way is necessary in order to + * return the desired data.
+ */ + 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}. A custom + * sort example:
+// current sort after sort we want
+// +-+------+ +-+------+
+// |1|First | |1|First |
+// |2|Last | |3|Second|
+// |3|Second| |2|Last |
+// +-+------+ +-+------+
+
+sortType: function(value) {
+ switch (value.toLowerCase()) // native toLowerCase():
+ {
+ case 'first': return 1;
+ case 'second': return 2;
+ default: return 3;
+ }
+}
+ * "ASC" or "DESC"). Defaults to
+ * "ASC".
+ */
+ sortDir : "ASC",
+ /**
+ * @cfg {Boolean} allowBlank
+ * @private
+ * (Optional) Used for validating a {@link Ext.data.Model model}, defaults to true.
+ * An empty value here will cause {@link Ext.data.Model}.{@link Ext.data.Model#isValid isValid}
+ * to evaluate to false.
+ */
+ allowBlank : true,
+
+ /**
+ * @cfg {Boolean} persist
+ * False to exclude this field from the {@link Ext.data.Model#modified} fields in a model. This
+ * will also exclude the field from being written using a {@link Ext.data.writer.Writer}. This option
+ * is useful when model fields are used to keep state on the client but do not need to be persisted
+ * to the server. Defaults to true.
+ */
+ persist: true
+});