非法查询表达式：没有哈希关键条件在查询中发现，在AWS查询

Question

我有表AWS移动枢纽和我使用它

public class UserstopcoreDO { 
    private String _userId; 
    private String _usertoplevel; 
    private String _usertopscore; 
    private String _username; 

    @DynamoDBHashKey(attributeName = "userId") 
    @DynamoDBAttribute(attributeName = "userId") 
    public String getUserId() { 
     return _userId; 
    } 

    public void setUserId(final String _userId) { 
     this._userId = _userId; 
    } 

    @DynamoDBAttribute(attributeName = "usertoplevel") 
    public String getUsertoplevel() { 
     return _usertoplevel; 
    } 

    @DynamoDBAttribute(attributeName = "username") 
    public String getUsername() { 
     return _username; 
    } 

    public void setUsername(final String _username) { 
     this._username = _username; 
    } 

    public void setUsertoplevel(final String _usertoplevel) { 
     this._usertoplevel = _usertoplevel; 
    } 

    @DynamoDBIndexHashKey(attributeName = "usertopscore", globalSecondaryIndexName = "usertopscore") 
    public String getUsertopscore() { 
     return _usertopscore; 
    } 

    public void setUsertopscore(final String _usertopscore) { 
     this._usertopscore = _usertopscore; 
    } 

} 

在表格下面的模型，我有1500+记录，现在我想所以我写了下面的查询

final DynamoDBQueryExpression<UserstopcoreDO> queryExpression = new DynamoDBQueryExpression<>(); 
      queryExpression.withLimit(10); 
      queryExpression.setScanIndexForward(false); 
      final PaginatedQueryList<UserstopcoreDO> results = mapper.query(UserstopcoreDO.class, queryExpression); 
      Iterator<UserstopcoreDO> resultsIterator = results.iterator(); 
      if (resultsIterator.hasNext()) { 
       final UserstopcoreDO item = resultsIterator.next(); 
       try { 
        Log.d("Item :",item.getUsertopscore()); 
       } catch (final AmazonClientException ex) { 
        Log.e(LOG_TAG, "Failed deleting item : " + ex.getMessage(), ex); 
       } 
      } 

从中取前10名的记录但是当我运行的代码它给我一个错误

Caused by: java.lang.IllegalArgumentException: Illegal query expression: No hash key condition is found in the query 

但在我的情况下，我不需要任何条件，因为我想获取前10条记录而不是一条特定记录。那么如何处理这种情况呢？

Answer 1

请在查询表达式中设置散列键。以下是主表和GSI的查询表达式示例（需要设置索引名称）。

查询主表： -

设置表格的散列键值。

UserstopcoreDO hashKeyObject = new UserstopcoreDO(); 
hashKeyObject.setUserId("1"); 

DynamoDBQueryExpression<UserstopcoreDO> queryExpressionForMainTable = new DynamoDBQueryExpression<UserstopcoreDO>() 
    .withHashKeyValues(hashKeyObject); 

查询索引： -

设置索引名和散列索引的键值。

UserstopcoreDO hashIndexKeyObject = new UserstopcoreDO(); 
    hashIndexKeyObject.setUsertoplevel("100"); 

DynamoDBQueryExpression<UserstopcoreDO> queryExpressionForGsi = new DynamoDBQueryExpression<UserstopcoreDO>() 
      .withHashKeyValues(hashIndexKeyObject).withIndexName("usertopscore"); 

GSI属性在映射： -

@DynamoDBIndexHashKey(attributeName = "usertoplevel", globalSecondaryIndexName = "usertopscore") 
public String getUsertoplevel() { 
    return _usertoplevel; 
} 

@DynamoDBIndexRangeKey(attributeName = "usertopscore", globalSecondaryIndexName = "usertopscore") 
public String getUsertopscore() { 
    return _usertopscore; 
}