给grails添加text映射支持

在grails中,domain class的String字段总是被映射成varchar,当然可以自己写xml映射文件解决这个问题,不过没有一劳永逸的解决方法了吗?于是开始搜索grails的论坛,发现这个特性还没有实现,开发人员倒是给出了一个issue:在constraints中实现type约束: propertyname(type:"text"),很郁闷了,还是自己来修改一下grails的源代码吧.
由于要在constraints中添加type约束,那么需要实现一个可以识别type的约束类,如下(在org.codehaus.groovy.grails.validation.ConstrainedProperty中):
先添加一个约束类字符串的声明, 反正他也不会用在validate,就在校验处理的时候什么也不作好了:
public static final String MAPPING_TYPE_CONSTRAINT = "type";
记得把这个类添加到map中
constraints.put(MAPPING_TYPE_CONSTRAINT, MappingTypeConstraint.class);

static class MappingTypeConstraint extends AbstractConstraint {
private String mapping_type;

public boolean supports(Class type) {
if (type == null)
return false;
return String.class.isAssignableFrom(type);
}

/*
* (non-Javadoc)
*
* @see org.codehaus.groovy.grails.validation.ConstrainedProperty.AbstractConstraint#setParameter(java.lang.Object)
*/
public void setParameter(Object constraintParameter) {
if (!(constraintParameter instanceof Comparable))
throw new IllegalArgumentException(
"Parameter for constraint ["
+ MAPPING_TYPE_CONSTRAINT
+ "] of property ["
+ constraintPropertyName
+ "] of class ["
+ constraintOwningClass
+ "] must implement the interface [java.lang.Comparable]");

this.mapping_type = (String) constraintParameter;
super.setParameter(constraintParameter);
}

public String getType() {
return this.mapping_type;
}

public String getName() {
return MAPPING_TYPE_CONSTRAINT;
}

protected void processValidate(Object target, Object propertyValue,
Errors errors) {
}
}

还要添加两个方法:
public Comparable getType() {
MappingTypeConstraint c = (MappingTypeConstraint) this.appliedConstraints
.get(MAPPING_TYPE_CONSTRAINT);
if (c == null) {
Range r = getRange();
if (r == null) {
return null;
} else {
return r.getFrom();
}
}
return c.getType();
}

public void setType(String type) {
if (!String.class.isInstance(propertyType)) {
throw new MissingPropertyException(
"Mapping type constraint can only be applied to a String property",
MAPPING_TYPE_CONSTRAINT, owningClass);
}

Constraint c = (Constraint) this.appliedConstraints
.get(MAPPING_TYPE_CONSTRAINT);
if (type == null) {
this.appliedConstraints.remove(MAPPING_TYPE_CONSTRAINT);
} else {
if (c != null) {
c.setParameter(type);
} else {
c = new MatchesConstraint();
c.setOwningClass(this.owningClass);
c.setPropertyName(this.propertyName);
c.setParameter(type);
this.appliedConstraints.put(MAPPING_TYPE_CONSTRAINT, c);
}
}
}
再添加个方法,偷懒点,只考虑"text"这种映射, 实际上我也只需要"text"映射:
public boolean hasMapTypeConstraints() {
return appliedConstraints.containsKey(MAPPING_TYPE_CONSTRAINT);
}
好了,前期准备工作基本上做好了,
然后去org.codehaus.groovy.grails.orm.hibernate.cfg.GrailsDomainBinder
修改一下bindSimpleValue方法就ok了:

private static void bindSimpleValue(GrailsDomainClassProperty grailsProp, SimpleValue simpleValue,Mappings mappings) {
// set type

simpleValue.setTypeName(grailsProp.getType().getName());

//添加text映射支持
Map cs = (Map)grailsProp.getDomainClass().getConstrainedProperties();
if (cs != null) {
ConstrainedProperty cp = (ConstrainedProperty)cs.get(grailsProp.getName());
if (cp != null && cp.hasMapTypeConstraints()) {
simpleValue.setTypeName(Hibernate.TEXT.getName());

System.out.println("TEXT Mapping: for =>" + grailsProp.getName());
}

}


Table table = simpleValue.getTable();
Column column = new Column();
if(grailsProp.isManyToOne())
column.setNullable(false);

column.setValue(simpleValue);
bindColumn(grailsProp, column);

if(table != null) table.addColumn(column);

simpleValue.addColumn(column);
}

ok,重新打包放到grails的dist目录下面,这样我们就可以在grails的domainclass中使用这样的约束:
def constraints = {
content(length:10..20000,blank:false, type:"text")
}
于是content的类型就映射到了Hibernate.Text上面去了.而不是原先的varchar