dav*_*tto 5 javascript extjs models extjs4.1
我的问题很长......所以,请耐心等待:)
我正在使用ExtJS 4中的模型,但是我在关联方面遇到了一些问题,因此我创建了一个函数来为我执行自动模型创建.让我们假设我需要解析以下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"
}
}, ...]
}
itens代表省份(巴西葡萄牙语的Estados),其中有一个国家(巴西葡萄牙语País).我试图使用ExtJS关联,但我认为它就像Java关系一样,我错了.好吧,对于这个JSON,我有这些Java类和这些Ext模型(模型也是使用提供的函数创建的).
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
}
创建模型的功能
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
});
};
使用函数创建模型
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
]
});
上面的代码与此相对应.我创建了自动化嵌套数据字段创建的函数(因为我说的关联问题).
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" }
]
});
好的,这些模型(使用我的createModel函数创建)与我的JsonStores非常兼容.到目前为止,Java端的所有映射关联都不为null,因此,我的商店总是有嵌套数据要处理.现在,我必须处理一些可以具有空关联的实体,并且我的问题就开始了.需要处理此场景的商店不起作用(在存储操作中抛出异常,表示字段为空).我正在使用Gson从我的实体创建JSON.它的默认行为是不对序列化空字段,它们将在客户端未定义,所以我虽然如果我序列化空字段(发送null)将使Ext实现空字段而不是尝试处理它.为此,我使用此代码创建Gson:
Gson gson = new GsonBuilder().serializeNulls().create();
好的,现在正在生成具有空关联的JSON,但是Ext继续抱怨.我试图使用字段映射和defaultValue配置没有成功.为了简单起见,让我们使用Estados和Países(Privinces和Countries)的例子,其中Pais不再是@NotNull.带有空pais的JSON就像:
{
"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"
}
}, ...]
}
使用此代码,pais.id,pais.nome和pais.sigla字段将不可用,因为pais属性为null.所以,我的问题是:当存储空为null或未定义时,如何使存储忽略某些字段？我已经尝试寻找一个没有成功的解决方案......非常感谢你!
编辑:在服务器端的一些可能的解决方案中考虑整个晚上之后,我在最后15分钟内实现了一个解决方案,但我确实不喜欢它...它是一种在使用之前遍历每个对象"对象树"的反射方法Gson将默认值设置为null的字段.它正在运行,但JSON变得越来越不必要.遍历方法:
/**
* 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();
}
}
我想你怎么看...谢谢!
编辑2:再次问好.我放弃!:)我将使用我在上面发布的解决方案.我发现了一些补丁来改善与模型和网格的关系.我测试了它们,但是空字段的问题仍然存在(至少错误消失了).好的,现在是时候继续开发了.应用程序完成后,我将回到此问题,尝试改进我的解决方案.谢谢!
不太确定这是否是问题所在，因为您没有给出确切的错误；但我之前遇到过可选嵌套数据的问题，解决方案是在模型中创建一个映射函数：
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; } }
]
});