Without saving SHA1 digest string in table directly. Is it possible to format the column in select statement ?
For example (Hope you know what i mean):
#item = Item.where(Digest::SHA1.hexdigest id.to_s:'356a192b7913b04c54574d18c28d46e6395428ab')
No, not the way you want it. The hexdigest method you're using won't be available at the database level. You could use database-specific functions though.
For example:
Item.where("LOWER(name) = ?", entered_name.downcase)
The LOWER() function will be available to the database so it can pass the name column to it.
For your case, I can suggest two solutions:
Obviously, store the encrypted field in the table. And then match.
key = '356a192b7913b04c54574d18c28d46e6395428ab'
Item.where(encrypted_id: key)
Iterate over all column values (ID, in your case) and find the one that matches:
all_item_ids = Item.pluck("CAST(id AS TEXT)")
item_id = all_item_ids.find{ |val| Digest::SHA1.hexdigest(val) == key }
Then you could use Item.find(item_id) to get the item or Item.where(id: item_id) to get an ActiveRecord::Relation object.
Related
I like to write a dynamoDb query in which I filter for a certain field, sounds simple.
All the examples I find always include the partition key value, which really confuses me, since it is unique value, but I want a list.
I got id as the partition key and no sort key or any other index. I tried to add partner as an index did not make any difference.
AttributeValue attribute = AttributeValue.builder()
.s(partner)
.build();
Map<String, AttributeValue> expressionValues = new HashMap<>();
expressionValues.put(":value", attribute);
Expression expression = Expression.builder()
.expression("partner = :value")
.expressionValues(expressionValues)
.build();
QueryConditional queryConditional = QueryConditional
.keyEqualTo(Key.builder()
.partitionValue("id????")
.build());
Iterator<Product> results = productTable.query(r -> r.queryConditional(queryConditional)
Would appreciate any help. Is there a misunderstandig on my side?
DynamoDB has two distinct, but similar, operations - Query and Scan:
Scan is for reading the entire table, including all partition keys.
Query is for reading a specific partition key - and all sort key in it (or a contiguous range of sort key - hence the nickname "range key" for that key).
If your data model does not have a range key, Query is not relevant for you - you should use Scan.
However this means that each time you call this query, the entire table will be read. Unless your table is tiny, this doesn't make economic sense, and you should reconsider your data model. For example, if you frequently look up results by the "partner" attribute, you can consider creating a GSI (global secondary index) with "partner" as its partition key, allowing you to quickly and cheapy fetch the list of items with a given "partner" value without scanning the entire table.
I have the following JSON in dynamo:
{
cdItem: "123456",
dtItem: "2021-03-01"
}
My hashkey is cdItem.
I would need my dtItem also be a key. So that if I send an item with the same cdItem, but different dtItem, it creates a new record and does not update the existing one.
How can I do this? Or, is it possible to do this?
There are multiple ways you can implement this and they depend on your access patterns.
If you only want to request an item for which you know both the cdItem as well as the dtItem values you could just overload the partition key by concatenating them, e.g. 123456#2021-03-01 that way you could keep your existing table.
A more flexible solution would be using a composite primary key, which is a combination of a partition and a sort key. This requires you to create a new table.
I'd set it up like this:
cdItem (Partition Key)
dtItem (Sort Key
123456
2021-02-27
123456
2021-02-28
123456
2021-03-01
654321
2021-03-01
You'll have to provide both of those attributes on each PutItem request.
You can also call GetItem with both values to retrieve a single item and you can select all dtItem values for a given cdItem value using the Query API as well as do some filtering on the value of dtItem.
I'm making a Microsoft Access table where one of the fields is a list of pre-made options. When I make a SQL query on that table it returns the values of the list as strings containing the spelled out choice. I would like to assign numerical values to each element of the list so a SQL query returns a number instead. How do I do this? I know it's possible because I have an access file with such a list but I'm unable to recreate it.
An easy way to do this is to have your combo box use a query of the table as a Rowsource. This query would have the table unique ID in the first field and the field you wish to return as the second field. Then change the setting on the combo box for "Column Count" to 2. If you want to show both fields change the "Column Widths" value to 1"; 1". If you want to show only one field, change the value of one you do not want to see to 0. Now we you refer to this list in an SQL queries, it will use the ID field but show the user the string field.
I have Tags as partition key in my table, and when I am trying to query I am getting AttributeError.
Below is my code:
kb_table = boto3.resource('dynamodb').Table('table_name')
result = kb_table.query(
KeyConditionExpression=Key('Tags').contains('search term')
)
return result['Items']
Error:
"errorMessage": "'Key' object has no attribute 'contains'"
Basically I want to search through the table where I the field is having that search term. I have achived it using scan but I have read everywhere that we should not use that.
result = kb_table.scan(
FilterExpression="contains (Tags, :titleVal)",
ExpressionAttributeValues={ ":titleVal": "search term" }
)
So I have changed my partition-key to Tags along with a sort-key so that I can achieve this using query but now I am getting this error.
Any idea how to get this working?
In order to use Query you must specify one partition to access, you cannot wildcard a partition or specify multiple keys.
KeyConditionExpression
The condition that specifies the key value(s)
for items to be retrieved by the Query action.
The condition must perform an equality test on a single partition key
value.
Assuming you want to search the whole table for tags, a scan is the most appropriate approach.
EDIT: You can use Query with the exact search term, but im guessing that is not what you want.
kb_table = boto3.resource('dynamodb').Table('table_name')
result = kb_table.query(
KeyConditionExpression=Key('Tags').eq('search term')
)
return result['Items']
I'm using the following: dynamodb2, boto, python. I have the following code for creating a table:
table = Table.create('mySecondTable',
schema=[HashKey('ID')],
RangeKey('advertiser'),
throughput={'read':5,'write':2},
global_indexes=[GlobalAllIndex('otherDataIndex',parts=[
HashKey('date',data_type=NUMBER),
RangeKey('publisher', date_type=str),
],throughput={'read':5,'write':3})],
connection=conn)
I would like to be able to have the following data that I can query by:
ID, advertiser, date, publisher, size, and color
That means I need a different schema. When I add additional points it does not query unless the column name is listed in the schema.
The problem however is that right now I am only able to query by Id, advertiser, date, and publisher in this case. How can I add additional columns that I can query by?
I read this which appears to say that it is possible:
http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GSI.html
However there is no example here:
http://boto.readthedocs.org/en/latest/dynamodb2_tut.html
I tried adding an additional range key however it doesn't work (cannot have duplicates)
I'd like it to be like:
table = Table.create('mySecondTable',
schema=[
RangeKey('advertiser'),
otherKey('date')
fourthKey('publisher') ... etc
throughput={'read':5,'write':2},
connection=conn)
Thanks!
If you want to add additional range keys you need to use Local secondary index.
You can query the LSI in the same way that you query the base table. You need to provide an exact value for the hashkey and a comparison-predicate for range key.