GreenDao在循环中添加or和条件

Question

我需要添加一些or子句来查询。我需要在循环中执行。

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

我如何才能正确地添加这些or条件，因为上面的工作不像预期的那样。我想为每个症状添加or

Answer 1

如果您查看文档，您将看到whereOr()接受无限多的条件。你要做的是一次性将它们全部添加到数组中:

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接受两个非数组的where条件和一个椭圆形参数，该参数接受一个数组或一个额外的以逗号分隔的对象列表。所以你可能需要做一些像这样的事情来让它正常工作:

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

附录:看起来您使用的api与文档不匹配，可能是旧版本的greenDAO。我根据当前文档编写了这个解决方案。我不能保证它对你有用。我建议尽可能更新。

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

我也有同样的问题，所以我在Util类中添加了自己的方法，当我在数组中有一个或多个whereconcondition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);

默认值:不能使用QueryBuilder中的Builder模式

在这里，我分享了一些代码，可以节省您开发DAO方法的时间。

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));
    }
} 

使用这个类，您可以对一行中的多个"values字符串"执行具有相同属性的whereOr操作。清理我的代码是必要的:)。但是，您只能执行简单的操作，例如在类中声明的变量。

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