Query dynamically with greenDao

Question

I need to verify some conditions to create a complete query:

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));

So is it possible to concatenate query builder conditions and create query builder dynamically? or anything so:

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

How make that in greenDao?

Answer 1

QueryBuilder.and() and QueryBuilder.or() are used to combine WhereConditions. The resulting WhereConditions have to be used inside QueryBuilder.where() (which will combine the conditions using AND) or QueryBuilder.whereOr().

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Please notice, that all your queries don't make much sense. As consequence the code I give you may not work as you expected, as I am just guessing what you expect. as example you can take qb.whereOr(MyObjDao.Properties.Prop2.eq(someValue),MyObjDao.Properties.Prop2.eq(someValue))

This translates to where (Prop2 = someValue OR Prop2 = someValue) or maybe to where (Prop2 = 'someValue' OR Prop2 = 'someValue'). In each of them the OR and the second statement are obsolete.

Another example is (a = '%'+condition1 or a = '%'+condition1+'%' or a = condition1 + '%') and (b = '%'+condition2 or b = '%'+condition2+'%' or b = condition2 + '%') and .... If you are not searching for strings with % in it, the query with a where-clause like this is going to return none or false results.

---

For:

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

You can use something like this:

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

Of course you can use another approach without dynamic list as well:

For:

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));

You can use this:

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();

As you see there are a lot of possiblities how you can combine WhereConditions at runtime using greendao. But as long as you don't give a detailed example and description of what you really want to do, nobody can help you.

By the way:

• Using where() or whereOr() doesn't make any difference, if you are only using one WhereCondition.
• you probably wanted to query: (a like '%'+condition1 or a like '%'+condition1+'%' or a like condition1 + '%') instead of (a = '%'+condition1 or a = '%'+condition1+'%' or a = condition1 + '%').
• notice, that (a like '%'+condition1 or a like '%'+condition1+'%' or a like condition1 + '%') is equal to (a like '%'+condition1+'%') since every result that matches a like '%'+condition1 or a like condition1+'%' will also match a like '%'+condition1+'%'.