Fields are used to define what a Model is. They aren't instantiated directly - instead, when we create a class -that extends Ext.data.Model, it will automatically create a Field instance for each field configured in a -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 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 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 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
-
-
-(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:
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 type is specified as "date".
A format string for the 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 Date
- -(Optional) A path expression for use by the Ext.data.reader.Reader implementation -that is creating the 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 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.
- -The name by which the field is referenced within the Model. This is referenced by, for example,
-the dataIndex property in column definition objects passed to 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.
False to exclude this field from the Ext.data.Model.modified fields in a model. This -will also exclude the field from being written using a 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.
-(Optional) Initial direction to sort ("ASC" or "DESC"). Defaults to
-"ASC".
(Optional) Initial direction to sort ("ASC" or "DESC"). Defaults to
-"ASC".
(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 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;
- }
-}
-(Optional) The data type for automatic conversion from received data to the stored value if 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 Ext.data.Types class.
- - -Developers may create their own application-specific data types by defining new members of the -Ext.data.Types class.
- -(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 - -