使用greenDao动态查询

Question

我需要验证一些条件来创建一个完整的查询:

QueryBuilder qb = getMyObjDao().queryBuilder();

if(someCondition)

 qb.where(MyObjDao.Properties.Prop1.eq(someValue)); 

else
qb.whereOr(MyObjDao.Properties.Prop2.eq(someValue),MyObjDao.Properties.Prop2.eq(someValue));

if(someOtherCondition)

 qb.where(MyObjDao.Properties.Prop3.eq(someValue)); 

其他

 qb.whereOr(MyObjDao.Properties.Prop4.eq(someValue));

那么是否可以连接查询构建器条件并动态创建查询构建器？或其他任何事情:

(a ='%'+ condition1或a ='%'+ condition1 +'%'或a = condition1 +'%')和
|(b ='%'+ condition2或b ='%'+ condition2 +'%'或b = condition2 +'%')和....

如何在绿道？

Answer 1

QueryBuilder.and()并QueryBuilder.or()用于组合WhereConditions.结果WhereCondition必须在内部使用QueryBuilder.where()(将结合使用的条件AND)或QueryBuilder.whereOr().

请注意,您的所有查询都没有多大意义.因此,我给你的代码可能无法按预期工作,因为我只是猜测你的期望.例如,你可以采取qb.whereOr(MyObjDao.Properties.Prop2.eq(someValue),MyObjDao.Properties.Prop2.eq(someValue))

这转化为where (Prop2 = someValue OR Prop2 = someValue)或可能转化为where (Prop2 = 'someValue' OR Prop2 = 'someValue').在每个中,OR和第二个语句都是过时的.

另一个例子是(a = '%'+condition1 or a = '%'+condition1+'%' or a = condition1 + '%') and (b = '%'+condition2 or b = '%'+condition2+'%' or b = condition2 + '%') and .... 如果你没有在其中搜索字符串%,那么带有这样的where子句的查询将返回none或false结果.

对于:

(a = '%'+condition1 or a = '%'+condition1+'%' or a = condition1 + '%') and
(b = '%'+condition2 or b = '%'+condition2+'%' or b = condition2 + '%') and ....

你可以使用这样的东西:

ArrayList<WhereCondition> and = new ArrayList<WhereCondition>();

if (condition1 != null) {
    and.add(queryBuilder.or(
            YourDao.Properties.a.eq("%"+condition1),
            YourDao.Properties.a.eq("%"+condition1+"%"),
            YourDao.Properties.a.eq(condition1+"%")));
}

if (condition2 != null) {
    and.add(queryBuilder.or(
            YourDao.Properties.a.eq("%"+condition2),
            YourDao.Properties.a.eq("%"+condition2+"%"),
            YourDao.Properties.a.eq(condition2+"%")));
}

...

if (and.size() == 1) {
    queryBuilder.where(and.get(0));
} else if (and.size() > 1) {
    WhereCondition first = and.remove(0);
    queryBuilder.where(first, and.toArray(new WhereCondition[and.size()]));
}

UPDATE

当然,您也可以使用另一种没有动态列表的方法:

对于:

QueryBuilder qb = getMyObjDao().queryBuilder();

if ( someCondition )

 qb.where(MyObjDao.Properties.Prop1.eq(someValue)); 

else
qb.whereOr(MyObjDao.Properties.Prop2.eq(someValue),MyObjDao.Properties.Prop2.eq(someValue));

if ( someOtherCondition )

 qb.where(MyObjDao.Properties.Prop3.eq(someValue)); 

else

 qb.whereOr(MyObjDao.Properties.Prop4.eq(someValue));

你可以用这个:

QueryBuilder<MyObj> queryBuilder = getMyObjDao().queryBuilder();
WhereCondition where = null;

if (someCondition1) {
    WhereCondition cond = MyObjDao.Properties.Prop1.eq(someValue);
    if (where == null) {
        where = cond;
    } else {
        where = queryBuilder.and(where, cond);
    }
} else {
    WhereCondition cond = queryBuilder.or(
            MyObjDao.Properties.Prop2.eq(someValue),
            MyObjDao.Properties.Prop2.eq(someOtherValue));
    if (where == null) {
        where = cond;
    } else {
        where = queryBuilder.and(where, cond);
    }
}

if (someOtherCondition) {
    WhereCondition cond = MyObjDao.Properties.Prop3.eq(someValue);
    if (where == null) {
        where = cond;
    } else {
        where = queryBuilder.and(where, cond);
    }
} else {
    WhereCondition cond = MyObjDao.Properties.Prop4.eq(someValue);
    if (where == null) {
        where = cond;
    } else {
        where = queryBuilder.or(where, cond2);
    }
}

List<YourObj> result = queryBuilder.where(where).list();

如您所见,如何在运行时使用greendao组合WhereConditions有很多可能性.但只要您没有详细说明您真正想做的事情,就没有人可以帮助您.

顺便说说:

• 如果您只使用一个WhereCondition,则使用where()或whereOr()不会产生任何差异.
• 你可能想查询:(a like '%'+condition1 or a like '%'+condition1+'%' or a like condition1 + '%')而不是(a = '%'+condition1 or a = '%'+condition1+'%' or a = condition1 + '%').
• 注意,这(a like '%'+condition1 or a like '%'+condition1+'%' or a like condition1 + '%')等于(a like '%'+condition1+'%')每个匹配a like '%'+condition1或a like condition1+'%'匹配的结果a like '%'+condition1+'%'.