Question

我需要添加一些or子句来查询。我需要在循环中完成它。

StringTokenizer st = new StringTokenizer(symptoms, ",");
while(st.hasMoreTokens()){
     qb.whereOr(Properties.Symptom.like("%" + st.nextToken() + "%"));
}

如何正确添加这些or条件，因为上面的内容无法按预期工作。我想为每个症状添加or。

Answer 1

If you look at the documentation，你会看到whereOr（）采用无限数量的条件。你想要做的是在数组中一次性添加它们：

StringTokenizer st = new StringTokenizer(symptoms, ",");

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

while(st.hasMoreTokens()){
     whereConditions.add(Properties.Symptom.like("%" + st.nextToken() + "%"));
}

// Give the ArrayList an already allocated array to place its contents in.
WhereCondition[] conditionsArray = new WhereCondition[whereConditions.size()];
conditionsArray = whereConditions.toArray(conditionsArray);

qb.whereOr(conditionsArray);

看起来文档中的方法调用需要两个非数组WhereConditions，然后是一个ellipsized参数，它接受一个数组或另外一个以逗号分隔的对象列表。因此，您可能需要执行以下操作才能使其正常工作：

qb.whereOr(conditionsArray[0], conditionsArray[1], Arrays.copyOfRange(conditionsArray, 2, conditionsArray.length);

ADDENDUM：看起来你正在使用与文档不匹配的api，可能是旧版本的greenDAO。我根据当前的文档编写了这个解决方案。我不能保证它会对你有用。如果可能，我建议更新。

Answer 2

试试这个：

StringTokenizer st = new StringTokenizer(symptoms, ",");
WhereCondition where = null;
while(st.hasMoreTokens()){
    if (where != null) {
        where = qb.or(where, Properties.Symptom.like("%" + st.nextToken() + "%"));
    } else {
        where = Properties.Symptom.like("%" + st.nextToken() + "%");
    }
}
qb.where(where).list();

Answer 3

我遇到了同样的问题所以我在Util类中添加了自己的方法，以便在数组中有一个或多个WhereCondition时执行相同的行为。

这是我的网关方法：

public static QueryBuilder whereOr(QueryBuilder queryBuilder, WhereCondition[] whereConditions){
        if(whereConditions == null) return queryBuilder.where(null);
        else if(whereConditions.length == 1) return queryBuilder.where(whereConditions[0]);
        else return queryBuilder.whereOr(whereConditions[0], whereConditions[1], Arrays.copyOfRange(whereConditions, 2, whereConditions.length));
    }

使用：Util.whereOr(queryBuilder, whereConditionsArray);

默认：使用此方法不能使用QueryBuilder中的Builder模式

（稍后）在这里，我分享了一些代码，可以在开发DAO方法时节省时间。

public class QueryBuilderUtil {
    public static final String EQ = "=?";
    public static final String NOTEQ = "<>?";
    public static final String LIKE = " LIKE ?";
    public static final String GE = ">=?";
    public static final String LE = "<=?";
    public static final String GT = ">?";
    public static final String LT = "<?";


    public static QueryBuilder whereOrOnSamePropertyWithDifferentValues(QueryBuilder queryBuilder, Property property, String operation, String values, String separator) {
        return whereOrOnSamePropertyWithDifferentValues(queryBuilder, property, operation, values.split(separator));

    }

    public static QueryBuilder whereOrOnSamePropertyWithDifferentValues(QueryBuilder queryBuilder, Property property, String operation, String[] values) {
        WhereCondition[] whereConditions = new WhereCondition[values.length];
        int i = 0;
        for (String value : values) {
            whereConditions[i++] = new WhereCondition.PropertyCondition(property, operation, value);
        }
        return whereOr(queryBuilder, whereConditions);
    }

    public static QueryBuilder whereOr(QueryBuilder queryBuilder, WhereCondition[] whereConditions) {
        if (whereConditions == null) return queryBuilder.where(null);
        else if (whereConditions.length == 1) return queryBuilder.where(whereConditions[0]);
        else return queryBuilder.whereOr(whereConditions[0], whereConditions[1], Arrays.copyOfRange(whereConditions, 2, whereConditions.length));
    }
}

使用此类，您可以在倍数上执行具有相同属性的whereOr＆＃34;值字符串＆＃34;在一条线上。有必要清理我的代码:)。但是，您只能执行类似于在类中声明的变量之类的简单操作。

示例：

public List<Block> loadAllByModId(String mods_id) {
        synchronized (this) {
            QueryBuilder<Block> queryBuilder = queryBuilder();
            QueryBuilderUtil.whereOrOnSamePropertyWithDifferentValues(queryBuilder, Properties.ModId, QueryBuilderUtil.EQ, mods_id, ";");
            query_list = queryBuilder.build();
        }
        Query<Block> query = query_list.forCurrentThread();
        return query.list();
    }

希望有所帮助

GreenDao whereOr和条件在循环中添加

3 个答案: