GreenDao其中，或条件在循环中添加

Question

我需要添加一些or子句进行查询。我需要循环执行。

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

我如何正确添加这些or条件，因为上述操作无法正常工作。我想为每种症状添加or。

Answer 1

If you look at the documentation，您会看到whereOr()接受了无穷多个条件。您想要做的是将它们全部一次添加到数组中：

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);

看来文档中的方法调用采用了两个非数组的WhereConditions，然后是一个椭圆形的参数，该参数接受一个数组或其他以逗号分隔的对象列表。因此，您可能必须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));

附录：您似乎在使用与文档不匹配的API，可能是较旧的greenDAO版本。我根据当前文档编写了该解决方案。我不能保证它会为您工作。我建议尽可能进行更新。

Answer 2

尝试一下：

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

我有相同的问题，所以当我在数组中有一个或多个WhereCondition时，我在Util类中添加了自己的方法，以执行相同的行为。

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));
    }

用途：Util.whereOr(queryBuilder, whereConditionsArray);

默认：无法通过这种方法使用QueryBuilder中的构建器模式

（（稍后再说），在这里，我与您分享一些代码，这些代码可以在开发DAO方法时节省您的时间。

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));
    }
} 

使用此类，您可以在一行中对多个“值字符串”执行相同属性的whereOr。有必要清理我的代码:)。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();
    } 
希望有帮助