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AWS SDK Java DynamoDB - Query with Expression Attribute Name - An expression attribute value used in expression is not defined

Similar to: I cannot query my dynamodb table from aws lambda due to wrong filterexpression? and DynamoDB update error Invalid UpdateExpression: An expression attribute value used in expression is not defined
I am trying to code a way to query DynamoDB tables using partial matches on Partition Key / Sort Key in Java.
The DynamoDB table I am trying to access has a Partition key of "Type" (A restricted key word in DynamoDB, I know, but not my choice) and a Sort key of "Id". I know the "Type" but not the full Id, so I have researched the Query method using AWS SDK 2.x source code and have implemented as shown below:
DynamoDBClient dynamoDbClient = DynamoDbClient.builder()
.region(Region.EU_WEST_1)
.credentialsProvider(StaticCredentialsProvider.create(awsCredentials))
.build();
String idKey = "wholeIdKey";
String idValue = "partialIdValue";
String typeValue = "typeValue";
Map<String, String> expressionNames = new HashMap<>();
expressionNames.put("#t", "Type");
QueryRequest request = QueryRequest.builder()
.tableName(tableName)
.keyConditionExpression("begins_with ( " + idKey + ", :" + idValue + " )
AND #t = :" + typeValue)
.expressionAttributeNames(expressionNames)
.build();
QueryResponse response = dynamoDbClient.query(request);
However, when I run this code, I get the following error message:
Exception in thread "main" software.amazon.awssdk.services.dynamodb.model.DynamoDbException:
Invalid KeyConditionExpression: An expression attribute value used in expression is not defined; attribute value: :typeValue
It's as if it's not recognizing the fact that I have told the code use the Expression Attribute Names feature to replace the "#t" with "Type" (Which is a reserved keyword in DynamoDB)
Can anyone help?
EDIT: References for code:
https://docs.aws.amazon.com/code-samples/latest/catalog/javav2-dynamodb-src-main-java-com-example-dynamodb-Query.java.html
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.ExpressionAttributeNames.html
https://www.javadoc.io/static/software.amazon.awssdk/dynamodb/2.7.14/software/amazon/awssdk/services/dynamodb/model/QueryRequest.html#expressionAttributeNames--

The name is fine, but you're prefixing both values with ':'. That causes a lookup in ExpressionAttributeValues, which you did not provide.
Never try to write dynamic values directly into the query string.

Your expressionAttributeName looks fine, but you forgot to provide a value for :typeValue so dynamoDB cannot know what to look for.
In addition to what you did, you need to add an expressionAttributeValue where you can provide proper values. See documentation here

Fixed Code for whoever wants it in the future (Thanks to #aherve and #MattTimmermans)
DynamoDBClient dynamoDbClient = DynamoDbClient.builder()
.region(Region.EU_WEST_1)
.credentialsProvider(StaticCredentialsProvider.create(awsCredentials))
.build();
String idKey = "wholeIdKey";
String idValue = "partialIdValue";
String typeValue = "typeValue";
String typeKey = "typeKey";
Map<String, String> expressionNames = new HashMap<>();
expressionNames.put("#t", "Type");
expressionNames.put("#i", "Id");
Map<String, AttributeValue> expressionValues = new HashMap<>();
expressionValues.put(":typeName", AttributeValue.builder().s(typeValue).build());
expressionValues.put(":idName", AttributeValue.builder().s(idValue).build());
QueryRequest request = QueryRequest.builder()
.tableName(tableName)
.keyConditionExpression("#t = :typeName AND begins_with ( #i, :idName )")
.expressionAttributeNames(expressionNames)
.expressionAttributeValues(expressionValues)
.build();
response = dynamoDbClient.query(request);

Java Spark: How to get value from a column which is JSON formatted string for entire dataset?

Needs some help here. I am trying to read data from Hive/CSV. There is a column whose type is string and the value is json formatted string. It is something like this:
| Column Name A |
|----------------------------------------------------------|
|"{"key":{"data":{"key_1":{"key_A":[123]},"key_2":[456]}}}"|
How can I get the value of key_2 and insert it to a new column?
I tried to create a new function to the get value via Gson
private BigDecimal getValue(final String columnValue){
JsonObject jsonObject = JsonParser.parseString(columnValue).getAsJsonOBject();
return jsonObject.get("key").getAsJsonObject().get("key_1").getAsJsonObject().get("key_2").getAsJsonArray().get(0).getAsBigDecimal();
}
But how i can apply this method to the whole dataset?
I was trying to achieve something like this:
Dataset<Row> ds = souceDataSet.withColumn("New_column", getValue(sourceDataSet.col("Column Name A")));
But it cannot be done as the data types are different...
Could you please give any suggestions?
Thx!
hx!
------------------Update---------------------
As #Mck suggested, I used get_json_object.
As my value contains "
"{"key":{"data":{"key_1":{"key_A":[123]},"key_2":[456]}}}"
I used substring to removed " and make the new string like this
{"key":{"data":{"key_1":{"key_A":[123]},"key_2":[456]}}}
Code for substring
DataSet<Row> dsA = sourceDataSet.withColumn("Column Name A",expr("substring(Column Name A, 2, length(Column Name A))"))
I used dsA.show() and confirmed the dataset looks correct.
Then I used following code try to do it
Dataset<Row> ds = dsA.withColumn("New_column",get_json_object(dsA.col("Column Name A"), "$.key.data.key_2[0]"));
which returns null.
However, if the data is this:
{"key":{"data":{"key_2":[456]}}}
I can get value 456.
Any suggestions why I get null?
Thx for the help!

Use get_json_object:
ds.withColumn(
"New_column",
get_json_object(
col("Column Name A").substr(lit(2), length(col("Column Name A")) - 2),
"$.key.data.key_2[0]")
).show(false)
+----------------------------------------------------------+----------+
|Column Name A |New_column|
+----------------------------------------------------------+----------+
|"{"key":{"data":{"key_1":{"key_A":[123]},"key_2":[456]}}}"|456 |
+----------------------------------------------------------+----------+

reading two variable values after decrypting

I am working on "Forgot Password". I am trying to create a reset token with email + current_time. email is user login whilst code will check if time >= 5 minutes then this link will not work. Here is my code:
// preparing token email + time
Date now = new Date();
String prepareToken = "?email="+email+"&tokenTime="+now.getTime();
// encrypt prepareToken value
Encryptor enc = new Encryptor();
resetToken = enc.encrypt(resetToken);
The token will be sent as for example as http://domainname.com/ForgotPassword?resetToken=adj23498ljj238809802340823
Problem:
When user click it then I got as request parameter and obviously decrypt this parameter but how can I get email in one String + time as another String
Please advise

If your issue is simply parsing the decoded String to get some sort of Map of your parameters, I'd suggest you to read Parse a URI String into Name-Value Collection .
Hope it helps.
EDIT :
Assuming you have the splitQuery(URL url) method from the previous link and that you successfully decoded the token :
public String getEmailFromToken(String decodedToken) {
// if you decoded your token it will looks like the prepareToken String
String stubUrl = "http://localhost"+decodedToken;
Map<String,String> map = splitQuery(new URL(stubUrl));
return map.get("timeToken");
}
I created a properly formed URL to respect the URL syntax.
With little tweak, you should be able to implement splitQuery for a String. I hope you can manage that.

How to get values custom metadata properties

I'm trying to get the metadata for an asset in the DAM. However, it seems that the metadata comes back as empty for properties that don't have "dc:" in front of them.
Resource rs = getResourceResolver().getResource(fileReference);
Asset asset = rs.adaptTo(Asset.class);
//this works
title = asset.getMetadataValue("dc:title").toString();
//this does not work.
//I have ensured that "mine.title" is a property and has string value assigned to it.
customTitle = asset.getMetadataValue("mine.title").toString():
//this does not work either
customTitle = asset.getMetadata("mine.title").toString():
Is there a way to get the value from a custom metadata property?

Assets at the end are simple nodes, so to get some property you can do something like this (depending on actual path of variable fileReference):
Resource metadataResource = rs.getChild("jcr:content/metadata");
ValueMap properties = ResourceUtil.getValueMap(metadataResource);
customTitle = properties.get("mine.title", "defaultValue")

"dc:title" comes with a registered namespace "dc" (Dublin Core) whereas "mine.title" does not.
That's the reason of title = asset.getMetadataValue("dc:title").toString(); giving you proper value than customTitle = asset.getMetadataValue("mine.title").toString()
You can attack this problem in many ways.
Change the property name to "dc:myTitle" and retrieve it in the same way you are retrieving "dc:title" [0]
You can retrieve the value of "mine.title" in the way Alex has described.
Resource rs = getResourceResolver().getResource(fileReference + "/jcr:content/metadata");
ValueMap damAssetValueMap = damResource.adaptTo(ValueMap.class);
String shortName = damAssetValueMap.get("shortName", String.class);
Register a new namespace and define options (in your case , its "mine").
A look at "/libs/dam/nodetypes" and "/libs/dam/options/metadata" might be helpful.
[0] Check "/libs/dam/options/metadata"

Why am getting an error cannot parse the key in google app engine for java

I had tried with the below way and got failed,
Query query = new Query("Users");
List<Entity> results = datastore.prepare(query).asList(FetchOptions.Builder.withLimit(PAGE_SIZE));
for (Entity user : results){
Key key = user.getKey();
System.out.println(key); // here am getting as Users(151),Users(152)...
From here am passing the "Key" as request parameter to a servlet.
In My Servlet,
String keyString = req.getParameter("key");
Key key = KeyFactory.stringToKey(keyString);
datastore.delete(key);
the error says "Cannot parse: Users(151)==" and the line of error is " Key key = KeyFactory.stringToKey(keyString);"
Can anyone suggest me an idea,
Your help will be appreciated.

Instead of passing Key as java objects to servlet, you should use this snippet to serialize
String encodedKey = KeyFactory.keyToString(key)
and this to deserialize
Key key = KeyFactory.stringToKey(encodedKey)