Dynamo db query using contains operator

Question

My table items are of the form of

function addDoc(movie,cb){
    var params = {
        TableName: "Movies",
        Item: {
            "year":  movie.year,
            "title": movie.title,
            "info":  movie.info,
            "genres" : movie.info.genres || []
        }
    };
    docClient.put(params, function(err, data) {
        bar.tick(1)
        i++;
        cb(err);
    });
}

async.eachLimit(allMovies,50,addDoc,function (err) {
    console.log(err)
    console.log("done inserting " + i + " movies");
});

I'm running this code :

var params = {
    TableName : "Movies",
    //ProjectionExpression:"#yr, title, genres, info.actors[0]",
    KeyConditionExpression: "#yr = :yyyy and contains(genres, :g1)",
    ExpressionAttributeNames:{
        "#yr": "year"
    },
    ExpressionAttributeValues: {
        ":yyyy":1992,
        ":g1" : "Drama"
    },
    //Select : "COUNT"
};
var start = Date.now()
docClient.query(params, function(err, data) {
    if (err) {
        console.error("Unable to query. Error:", JSON.stringify(err, null, 2));
    } else {
        console.log("time elapsed :",Date.now()-start);
        console.log("Query succeeded.");

        console.log(data)

    }
});

and I'm getting this error

"Invalid operator used in KeyConditionExpression: contains"

any idea?

notionquest · Accepted Answer · 2018-01-17 12:57:48Z

30

There are few things that need to be clarified here.

1) The Key attributes of DynamoDB has to be scalar data type. So, I believe the attribute genres can't be defined as SET or LIST data type

2) KeyConditionExpression - can refer to Hash and Sort key only. So, I presume the attribute genres is defined as SORT key of the table

3) contains can be used on FilterExpression on data types STRING, SET or LIST. It can't be used on KeyConditionExpression

Conclusion - Refer point 3 for straight forward answer

edited Jan 17, 2018 at 12:57

answered May 25, 2017 at 8:53

notionquest

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6 Comments

sid8491 Over a year ago

any idea how to perform seaching in text? as in substring searching? ex: search for blue in blue screen error

notionquest Over a year ago

@sid8491 You can use CONTAINS. Please note that it is a case sensitive match. FilterExpression: "contains (title, :titleVal)", ExpressionAttributeValues: { ":titleVal": "somevalue" }

notionquest Over a year ago

@sid8491 it can be used for string as well.

MK Yung Over a year ago

but the example here showed that contains can be used on KeyConditionExpression ? docs.aws.amazon.com/amazondynamodb/latest/developerguide/…

Vingtoft Over a year ago

@MKYung I'm also totally confused by now. Official docs clearly shows that 'contains' can me used in KeyConditionExpression

|

Armen Babakanian · Accepted Answer · 2022-04-15 04:07:54Z

0

Based on the SDK documentation, KeyConditionExpression supports the following expressions:

a = b — true if the attribute a is equal to the value b

a < b — true if a is less than b

a <= b — true if a is less than or equal to b

a > b — true if a is greater than b

a >= b — true if a is greater than or equal to b

a BETWEEN b AND c — true if a is greater than or equal to b, and less than or equal to c.

The following function is also supported:

begins_with (a, substr)— true if the value of attribute a begins with a particular substring.

see documentation page: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Query.html

answered Apr 15, 2022 at 4:07

Armen Babakanian

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