Conditional update Dynamodb on nested object

Question

I am trying to learn to use DynamoDB with C# I have Partial updates, Put, Delete working. Conditional update works (If the Attributes is part of root object).

I have the following model created.

Person with a lot of attributes. The following works:

Expression expr = new Expression();
expr.ExpressionStatement = "Age = :age";
expr.ExpressionAttributeValues[":age"] = 26;

UpdateItemOperationConfig config = new UpdateItemOperationConfig
{
    ConditionalExpression = expr,
    ReturnValues = ReturnValues.AllNewAttributes
};

Document updatedPerson2 = personCatalog.UpdateItem(doc, config);

But what if my condition was on the Pet Name?
I have tried a couple of approaches with no luck eg:

expr.ExpressionStatement = "Pet.Name = :name";
expr.ExpressionAttributeValues[":name"] = "Lilleper";

Hope someone can help :) Or just nudge me in the right direction.

Strange. If I cange it to: expr.ExpressionStatement = "Pet.Age = :age"; expr.ExpressionAttributeValues[":age"] = 30; it works? Doesn't string work? — Kiksen
– Kiksen, Commented Jan 27, 2017 at 6:36

Alexander Patrikalakis · Accepted Answer · 2017-03-29 06:56:00Z

2

Try externalizing the Name sub-attribute name to ExpressionAttributeNames.

Expression expr = new Expression();
expr.ExpressionStatement = "Pet.#name = :name";
expr.ExpressionAttributeNames["#name"] = "Name";
expr.ExpressionAttributeValues[":name"] = "Lilleper";

answered Mar 29, 2017 at 6:56

Alexander Patrikalakis

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1 Comment

Kiksen Over a year ago

Awesome :) Thanks for the help.

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