No hash key condition is found in the query

Question

I am trying to query my DynamoDB table for an individual record using a unique partition key:

DynamoDBQueryExpression queryExpression=new DynamoDBQueryExpression()
            .withHashKeyValues("parkurself")
            .withFilterExpression("Latitude>25")
            .withFilterExpression("Latitude<40")
            .withFilterExpression("Longitude>25")
            .withFilterExpression("Longitude<40")
            .withConsistentRead(false);
PaginatedQueryList<ParkingInfo> result=mapper.query(ParkingInfo.class, queryExpression);

However, I have received an error "No hash key condition is found in the query" The Logcat is being attached.

Caused by: java.lang.IllegalArgumentException: Illegal query expression: No hash key condition is found in the query
        at com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBMapper.processKeyConditions(DynamoDBMapper.java:2420)
        at com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBMapper.createQueryRequestFromExpression(DynamoDBMapper.java:2382)
        at com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBMapper.query(DynamoDBMapper.java:2166)
        at com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBMapper.query(DynamoDBMapper.java:2127)
        at monster.com.parkurself.QueryParkingInfo.doInBackground(QueryParkingInfo.java:63)
        at monster.com.parkurself.QueryParkingInfo.doInBackground(QueryParkingInfo.java:18)
        at android.os.AsyncTask$2.call(AsyncTask.java:295)
        at java.util.concurrent.FutureTask.run(FutureTask.java:237)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
        at java.lang.Thread.run(Thread.java:818)

I don't know how to fix it. Can anyone give me some help? Thank you in advance.

Thank you very much for your answers. However, my table has no range key, it only has a primary hash key. So, I do not know how to deal with it with only a hash key. — Yu Zou, Oct 09 '15 at 06:28

score 2 · Answer 1 · answered Oct 22 '15 at 14:55

As Mircea said, you need to create a class that encapsulates the entry first which it looks like you have done. The issue here is you have passed in the String class which has no mapping attributes.

Create an instance of the mapper class and set the hash key to the one you want to query. Pass that class into the query and it should work.

// Create object which maps to the query object.
ParkingInfo parkingInfo = new ParkingInfo();
parkingInfo.setID("parkurself");

DynamoDBQueryExpression<ParkingInfo> queryExpression = new DynamoDBQueryExpression<ParkingInfo>()
        .withHashKeyValues(parkingInfo)
        .withFilterExpression("Latitude>25")
        .withFilterExpression("Latitude<40")
        .withFilterExpression("Longitude>25")
        .withFilterExpression("Longitude<40")
        .withConsistentRead(false);

PaginatedQueryList<ParkingInfo> result = mapper.query(ParkingInfo.class, queryExpression);

score 1 · Answer 2 · answered Oct 09 '15 at 12:44

you are not going through the dynamo db mapper (http://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/services/dynamodbv2/datamodeling/DynamoDBMapper.html and http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/JavaSDKHighLevel.html) in order to use the DynamoDBQueryExpression you have to go through the mapper. what you pass into withHashKeyValues need to be an object instantiated from a class that has the right annotations on it. See example here:

http://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/services/dynamodbv2/datamodeling/DynamoDBMapper.html

you will need to create a class that has Parkurself, Longitude, Latitude as members and correctly tag them via attributes.

More about how to access DDB here: http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/AboutJava.html

If you don't want/need to use the mapper (i.e. high level api) you could go through the low level api.

True, but I think the question is for Android. See http://docs.aws.amazon.com/mobile/sdkforandroid/developerguide/dynamodb_om.html. — WestonE, Oct 09 '15 at 16:44
think the dynamo mapper usage pattern and the need to the mapper class still applies — Mircea, Oct 09 '15 at 17:02

No hash key condition is found in the query

2 Answers2