moto/tests/test_dynamodb/test_dynamodb_batch_get_item.py

import boto3
import sure  # noqa # pylint: disable=unused-import
import pytest

from moto import mock_dynamodb
from botocore.exceptions import ClientError


def _create_user_table():
    client = boto3.client("dynamodb", region_name="us-east-1")
    client.create_table(
        TableName="users",
        KeySchema=[{"AttributeName": "username", "KeyType": "HASH"}],
        AttributeDefinitions=[{"AttributeName": "username", "AttributeType": "S"}],
        ProvisionedThroughput={"ReadCapacityUnits": 5, "WriteCapacityUnits": 5},
    )
    client.put_item(
        TableName="users", Item={"username": {"S": "user1"}, "foo": {"S": "bar"}}
    )
    client.put_item(
        TableName="users", Item={"username": {"S": "user2"}, "foo": {"S": "bar"}}
    )
    client.put_item(
        TableName="users", Item={"username": {"S": "user3"}, "foo": {"S": "bar"}}
    )
    return client


@mock_dynamodb
def test_batch_items_returns_all():
    dynamodb = _create_user_table()
    returned_items = dynamodb.batch_get_item(
        RequestItems={
            "users": {
                "Keys": [
                    {"username": {"S": "user0"}},
                    {"username": {"S": "user1"}},
                    {"username": {"S": "user2"}},
                    {"username": {"S": "user3"}},
                ],
                "ConsistentRead": True,
            }
        }
    )["Responses"]["users"]
    assert len(returned_items) == 3
    assert [item["username"]["S"] for item in returned_items] == [
        "user1",
        "user2",
        "user3",
    ]


@mock_dynamodb
def test_batch_items_throws_exception_when_requesting_100_items_for_single_table():
    dynamodb = _create_user_table()
    with pytest.raises(ClientError) as ex:
        dynamodb.batch_get_item(
            RequestItems={
                "users": {
                    "Keys": [
                        {"username": {"S": "user" + str(i)}} for i in range(0, 104)
                    ],
                    "ConsistentRead": True,
                }
            }
        )
    ex.value.response["Error"]["Code"].should.equal("ValidationException")
    msg = ex.value.response["Error"]["Message"]
    msg.should.contain("1 validation error detected: Value")
    msg.should.contain(
        "at 'requestItems.users.member.keys' failed to satisfy constraint: Member must have length less than or equal to 100"
    )


@mock_dynamodb
def test_batch_items_throws_exception_when_requesting_100_items_across_all_tables():
    dynamodb = _create_user_table()
    with pytest.raises(ClientError) as ex:
        dynamodb.batch_get_item(
            RequestItems={
                "users": {
                    "Keys": [
                        {"username": {"S": "user" + str(i)}} for i in range(0, 75)
                    ],
                    "ConsistentRead": True,
                },
                "users2": {
                    "Keys": [
                        {"username": {"S": "user" + str(i)}} for i in range(0, 75)
                    ],
                    "ConsistentRead": True,
                },
            }
        )
    ex.value.response["Error"]["Code"].should.equal("ValidationException")
    ex.value.response["Error"]["Message"].should.equal(
        "Too many items requested for the BatchGetItem call"
    )


@mock_dynamodb
def test_batch_items_with_basic_projection_expression():
    dynamodb = _create_user_table()
    returned_items = dynamodb.batch_get_item(
        RequestItems={
            "users": {
                "Keys": [
                    {"username": {"S": "user0"}},
                    {"username": {"S": "user1"}},
                    {"username": {"S": "user2"}},
                    {"username": {"S": "user3"}},
                ],
                "ConsistentRead": True,
                "ProjectionExpression": "username",
            }
        }
    )["Responses"]["users"]

    returned_items.should.have.length_of(3)
    [item["username"]["S"] for item in returned_items].should.be.equal(
        ["user1", "user2", "user3"]
    )
    [item.get("foo") for item in returned_items].should.be.equal([None, None, None])

    # The projection expression should not remove data from storage
    returned_items = dynamodb.batch_get_item(
        RequestItems={
            "users": {
                "Keys": [
                    {"username": {"S": "user0"}},
                    {"username": {"S": "user1"}},
                    {"username": {"S": "user2"}},
                    {"username": {"S": "user3"}},
                ],
                "ConsistentRead": True,
            }
        }
    )["Responses"]["users"]

    [item["username"]["S"] for item in returned_items].should.be.equal(
        ["user1", "user2", "user3"]
    )
    [item["foo"]["S"] for item in returned_items].should.be.equal(["bar", "bar", "bar"])


@mock_dynamodb
def test_batch_items_with_basic_projection_expression_and_attr_expression_names():
    dynamodb = _create_user_table()
    returned_items = dynamodb.batch_get_item(
        RequestItems={
            "users": {
                "Keys": [
                    {"username": {"S": "user0"}},
                    {"username": {"S": "user1"}},
                    {"username": {"S": "user2"}},
                    {"username": {"S": "user3"}},
                ],
                "ConsistentRead": True,
                "ProjectionExpression": "#rl",
                "ExpressionAttributeNames": {"#rl": "username"},
            }
        }
    )["Responses"]["users"]

    returned_items.should.have.length_of(3)
    [item["username"]["S"] for item in returned_items].should.be.equal(
        ["user1", "user2", "user3"]
    )
    [item.get("foo") for item in returned_items].should.be.equal([None, None, None])


@mock_dynamodb
def test_batch_items_should_throw_exception_for_duplicate_request():
    client = _create_user_table()
    with pytest.raises(ClientError) as ex:
        client.batch_get_item(
            RequestItems={
                "users": {
                    "Keys": [
                        {"username": {"S": "user0"}},
                        {"username": {"S": "user0"}},
                    ],
                    "ConsistentRead": True,
                }
            }
        )
    ex.value.response["Error"]["Code"].should.equal("ValidationException")
    ex.value.response["Error"]["Message"].should.equal(
        "Provided list of item keys contains duplicates"
    )


@mock_dynamodb
def test_batch_items_should_return_16mb_max():
    """
    A single operation can retrieve up to 16 MB of data [...]. BatchGetItem returns a partial result if the response size limit is exceeded [..].

    For example, if you ask to retrieve 100 items, but each individual item is 300 KB in size,
    the system returns 52 items (so as not to exceed the 16 MB limit).

    It also returns an appropriate UnprocessedKeys value so you can get the next page of results.
    If desired, your application can include its own logic to assemble the pages of results into one dataset.
    """
    client = _create_user_table()
    # Fill table with all the data
    for i in range(100):
        client.put_item(
            TableName="users",
            Item={"username": {"S": f"largedata{i}"}, "foo": {"S": "x" * 300000}},
        )

    resp = client.batch_get_item(
        RequestItems={
            "users": {
                "Keys": [{"username": {"S": f"largedata{i}"}} for i in range(75)],
                "ConsistentRead": True,
            }
        }
    )

    resp["Responses"]["users"].should.have.length_of(55)
    unprocessed_keys = resp["UnprocessedKeys"]["users"]["Keys"]
    # 75 requested, 55 returned --> 20 unprocessed
    unprocessed_keys.should.have.length_of(20)

    # Keys 55-75 are unprocessed
    unprocessed_keys.should.contain({"username": {"S": "largedata55"}})
    unprocessed_keys.should.contain({"username": {"S": "largedata65"}})

    # Keys 0-55 are processed in the regular response, so they shouldn't show up here
    unprocessed_keys.shouldnt.contain({"username": {"S": "largedata45"}})