Invalid UpdateExpression when using parameter from ValueMap as index (REMOVE myArray[:index]) - amazon-dynamodb

I try to remove an element from an array. This operation
UpdateItemSpec updateItemSpec = new UpdateItemSpec()
.withPrimaryKey("id", id)
.withNameMap(new NameMap().with("#P", "myArray"))
.withValueMap(new ValueMap().withInt(":index", index))
.withUpdateExpression("REMOVE #P[:index]");
table.updateItem(updateItemSpec);
results with com.amazonaws.services.dynamodbv2.model.AmazonDynamoDBException: Invalid UpdateExpression: Syntax error; token: ":index", near: "[:index]"
If I remove ValueMap and concat string like this "REMOVE #P["+index+"]" it works fine but this solution looks ugly (like old bad SQL injection stuff). Is there a way to provide an index as a parameter?

REMOVE - Removes one or more attributes from an item
REMOVE - The UpdateExpression is expected to have attribute name only for REMOVE. It should not contain attribute value similar to SET.
There is no alternative other than String concatenation by some means.

Related

Populating an Apex Map from a SOQL query

// I have a custom metadata object named boatNames__mdt and I'm using two methods to get a list of picklist values in a String[];
First Method
Map<String, boatNames__mdt> mapEd = boatNames__mdt.getAll();
string boatTypes = (string) mapEd.values()[0].BoatPick__c;
// BoatPick__c is a textarea field (Eg: 'Yacht, Sailboat')
string[] btWRAP = new string[]{};
**btWRAP**.addAll(boatTypes.normalizeSpace().split(','));
Second Method
string[] strL = new string[]{};
Schema.DescribeFieldResult dfr = Schema.SObjectType.boatNames__mdt.fields.BoatTypesPicklist__c;
// BoatTypesPicklist__c is a picklist field (Picklist Values: 'Yacht, Sailboat')
PicklistEntry[] picklistValues = dfr.getPicklistValues();
for (PicklistEntry pick : picklistValues){
**strl**.add((string) pick.getLabel());
}
Map with SOQL query
Map<Id, BoatType__c> boatMap = new Map<Id, BoatType__c>
([Select Id, Name from BoatType__c Where Name in :btWRAP]);
When I run the above Map with SOQL query(btWRAP[]) no records show up.
But when I used it using the strl[] records do show up.
I'm stunned!
Can you please explain why two identical String[] when used in exact SOQL queries behave so different?
You are comparing different things so you get different results. Multiple fails here.
mapEd.values()[0].BoatPick__c - this takes 1st element. At random. Are you sure you have only 1 element in there? You might be getting random results, good luck debugging.
normalizeSpace() and trim() - you trim the string but after splitting you don't trim the components. You don't have Sailboat, you have {space}Sailboat
String s = 'Yacht, Sailboat';
List<String> tokens = s.normalizeSpace().split(',');
System.debug(tokens.size()); // "2"
System.debug(tokens); // "(Yacht, Sailboat)", note the extra space
System.debug(tokens[1].charAt(0)); // "32", space's ASCII number
Try splitting by "comma, optionally followed by space/tab/newline/any other whitespace symbol": s.split(',\\s*'); or call normalize in a loop over the split's results?
pick.getLabel() - in code never compare using picklist labels unless you really know what you're doing. Somebody will translate the org to German, French etc and your code will break. Compare to getValue()

Invalid type for parameter error when using put_item dynamodb

I want to write data in dataframe to dynamodb table
item = {}
for row in datasource_archived_df_join_repartition.rdd.collect():
item['x'] = row.x
item['y'] = row.y
client.put_item( TableName='tryfail',
Item=item)
but im gettin this error
Invalid type for parameter Item.x, value: 478.2, type: '<'type 'float''>', valid types: '<'type 'dict''>'
Invalid type for parameter Item.y, value: 696- 18C 12, type: '<'type 'unicode''>', valid types: '<'type 'dict''>'
Old question, but it still comes up high in a search and hasn't been answered properly, so here we go.
When putting an item in a DynamoDB table it must be a dictionary in a particular nested form that indicates to the database engine the data type of the value for each attribute. The form looks like below. The way to think of this is that an AttributeValue is not a bare variable value but a combination of that value and its type. For example, an AttributeValue for the AlbumTitle attribute below is the dict {'S': 'Somewhat Famous'} where the 'S' indicates a string type.
response = client.put_item(
TableName='Music',
Item={
'AlbumTitle': { # <-------------- Attribute
'S': 'Somewhat Famous', # <-- Attribute Value with type string ('S')
},
'Artist': {
'S': 'No One You Know',
},
'SongTitle': {
'S': 'Call Me Today',
},
'Year': {
'N': '2021' # <----------- Note that numeric values are supplied as strings
}
}
)
In your case (assuming x and y are numbers) you might want something like this:
for row in datasource_archived_df_join_repartition.rdd.collect():
item = {
'x': {'N': str(row.x)},
'y': {'N': str(row.y)}
}
client.put_item( TableName='tryfail', Item=item)
Two things to note here: first, each item corresponds to a row, so if you are putting items in a loop you must instantiate a new one with each iteration. Second, regarding the conversion of the numeric x and y into strings, the DynamoDB docs explain that the reason the AttributeValue dict requires this is "to maximize compatibility across languages and libraries. However, DynamoDB treats them as number type attributes for mathematical operations." For fuller documentation on the type system for DynamoDB take a look at this or read the Boto3 doc here since you are using Python.
The error message is indicating you are using the wrong type, it looks like you need to be using a dictionary when assigning values to item['x'] and item[y]. e.g.
item['x'] = {'value': row.x}
item['y'] = {'value': row.y}

Passing list of search string in contains in FilterExpression

Is there any way to pass a list of search strings in the contains() method of FilterExpression in DynamoDb?
Something like below:
search_str = ['value-1', 'value-2', 'value-3']
result = kb_table.scan(
FilterExpression="contains (title, :titleVal)",
ExpressionAttributeValues={ ":titleVal": search_str }
)
For now I can only think of looping through the list and scanning the table multiple times (as in below code), but I think it will be resource heavy.
for item in search_str:
result += kb_table.scan(
FilterExpression="contains (title, :titleVal)",
ExpressionAttributeValues={ ":titleVal": item }
)
Any suggestions.
For the above scenario, the CONTAINS should be used with OR condition. When you give array as input for CONTAINS, DynamoDB will check for the SET attribute ("SS", "NS", or "BS"). It doesn't looks for the sub-sequence on the string attribute.
If the target attribute of the comparison is of type String, then the
operator checks for a substring match. If the target attribute of the
comparison is of type Binary, then the operator looks for a
subsequence of the target that matches the input. If the target
attribute of the comparison is a set ("SS", "NS", or "BS"), then the
operator evaluates to true if it finds an exact match with any member
of the set.
Example:-
movies1 = "MyMovie"
movies2 = "Big New"
fe1 = Attr('title').contains(movies1)
fe2 = Attr('title').contains(movies2)
response = table.scan(
FilterExpression=fe1 or fe2
)
a little bit late but to allow people to find a solution i give here my method.
lets assume that in your DB you have a props called 'EMAIL you want to filter your scan on this EMAIL with a list of value. you can proceed as following.
list_of_elem=['mail1#mail.com','mail2#mail.com','mail3#mail.com']
#set an empty string to create your query
stringquery=""
# loop each element in your list
for index,value in enumerate(list_of_elem):
# add your query of contains with mail value
stringquery=stringquery+f"Attr('EMAIL').contains('{value }')"
# while your value is not the last element in list add the 'OR' operator
if index < len(list_of_elem)-1:
stringquery=stringquery+ ' | '
dynamodb = boto3.resource('dynamodb')
# Use eval of your query string to parse the string as filter expression
tableUser = dynamodb.Table('mytable')
tableUser.scan(
FilterExpression=eval(stringquery)
)

Simple.Data casting to ToList<string>()

I am using Simple.Data and want to know if I can Select a single column and then cast it to a list of string values. For example using the query below I get the error:
Cannot implicitly convert type 'Simple.Data.SimpleRecord' to 'string'
var result = _database.ParentRegionList.All()
.Select(_database.ParentRegionList.RegionName)
.Where(_database.ParentRegionList.RegionName.Like(startsWith + "%"))
.Distinct()
.ToList<string>();
However if I create a class LocationAutoComplete that has a single public property "RegionName" of type string then the cast works fine.
var result = _database.ParentRegionList.All()
.Select(_database.ParentRegionList.RegionName)
.Where(_database.ParentRegionList.RegionName.Like(startsWith + "%"))
.Distinct()
.ToList<LocationAutoComplete>();
The ToList<T> Simple.Data method expects you to be casting the contents of a SimpleRecord to an object, which is why it works with your LocationAutoComplete class. Full details can be found here.
If you are returning only one field which you wish to return as a scalar value or a list of scalar values, use the ToScalar<T> or ToScalarList<T> method instead. Full details can be found here
If RegionName is a varchar then all you need is
var result = _database.ParentRegionList.All()
.Where(_database.ParentRegionList.RegionName.Like(startsWith + "%"))
.Select(_database.ParentRegionList.RegionName)
.Distinct()
.ToList();
You don't need the <string>

How can I tell if E4X expression has a match or not?

I am trying to access an XMLList item and convert it to am XML object.
I am using this expression:
masonicXML.item.(#style_number == styleNum)
For example if there is a match everything works fine but if there is not a match then I get an error when I try cast it as XML saying that it has to be well formed. So I need to make sure that the expression gets a match before I cast it as XML. I tried setting it to an XMLList variable and checking if it as a text() propertie like this:
var defaultItem:XMLList = DataModel.instance.masonicXML.item.(#style_number == styleNum);
if(defaultItem.text())
{
DataModel.instance.selectedItem = XML(defaultItem);
}
But it still give me an error if theres no match. It works fine if there is a match.
THANKS!
In my experience, the simplest way to check for results is to grab the 0th element of the list and see if it's null.
Here is your code sample with a few tweaks. Notice that I've changed the type of defaultItem from XMLList to XML, and I'm assigning it to the 0th element of the list.
var defaultItem:XML =
DataModel.instance.masonicXML.item.(#style_number == styleNum)[0];
if( defaultItem != null )
{
DataModel.instance.selectedItem = defaultItem;
}
OK I got it to work with this:
if(String(defaultItem.#style_number).length)
Matt's null check is a good solution. (Unless there is the possibility of having null items within an XMLList.. probably not, but I haven't verified this.)
You can also check for the length of the XMLList without casting it to a String:
if (defaultItem.#style_number.length() > 0)
The difference to String and Array is that with an XMLList, length() is a method instead of a property.

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