How to search a value from array of objects in DynamoDB in node js

Question

For suppose the item is like

{
'EventType': 'git/push'
'EventTime': 1416251010,
'Commits': [
    {
        'id': '29d02aff...',
        'subject': 'Add the thing to the place'
    },
    {
        'id': '9d888fec...',
        'subject': 'Spelling errors'
    },
    ...
]

}

then I want the output like

{
'EventType': 'git/push'
'EventTime': 1416251010,
'Commits': [
    {
        'id': '29d02aff...',
        'subject': 'Add the thing to the place'
    }
 ]
}

can you please suggest me the DynamoDB filter. Thanks in advance.

Thanks notionquest for responding this post, I want to filter with EventType and subject from comments, actually, comments will contain more than one recode with the same subject, that is the case I want all the records with the matched subject. — RamMohan222
– RamMohan222, Commented Nov 3, 2017 at 5:32
If you know both the id and subject of the comments, then it is possible. Otherwise, it is not possible. — notionquest
– notionquest, Commented Nov 3, 2017 at 5:59
ok if I know id and subject how can I apply the filter condition — RamMohan222
– RamMohan222, Commented Nov 3, 2017 at 6:22

notionquest · Accepted Answer · 2017-11-03 16:51:05Z

4

CONTAINS function can be used to filter or find the data in DynamoDB list. However, please note that you need to have both the attributes (i.e. id and subject) of the object (complex object in terms of DynamoDB) to find the data in List.

CONTAINS is supported for lists: When evaluating "a CONTAINS b", "a" can be a list; however, "b" cannot be a set, a map, or a list.

Sample code:-

var table = "eventtype";
var params = {
    TableName: table,
    KeyConditionExpression: "EventType = :eventType",
    FilterExpression: "contains(Commits, :commitVal )",
    ExpressionAttributeValues: {
        ":eventType": 'git/push',
        ":commitVal": {
            'id': '29d02aff',
            'subject': 'Add the thing to the place'
        }
    }
};

docClient.query(params, function (err, data) {
    if (err) {
        console.error("Unable to read item. Error JSON:", JSON.stringify(err,
            null, 2));
    } else {
        console.log("GetItem succeeded:", JSON.stringify(data, null, 2));
    }
});

answered Nov 3, 2017 at 16:51

notionquest

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3 Comments

RamMohan222 Over a year ago

Thanks for your answer, Is it possible only with id.? in some situations I'm only known id I don't know a subject.

Nikhil Manapure Over a year ago

@Ram did you find a way to just check with id and not subject? I have a similar situation. Thanks!!

Lakindu Hewawasam Over a year ago

@RamMohan222, is there a way to get it with just ID?

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