Node-postgres - Flattening query result array

Question

I want to get a array of ids from my database table as a one-dimensional array.

I've used QueryArrayConfig for my query string with the rowMode set to "array". I get my ids correctly, but it returns a two-dimensional array.

            const idQuery: pg.QueryArrayConfig = {
                name: 'get-ids',
                text: 'SELECT id FROM MySchema.SomeTable'
                rowMode: "array"
            };

            pool.query(idQuery).then((result: pg.QueryResult) => {
                console.log(result.rows);
                ...

I get : [ [ 1 ], [ 2 ] ], but I need [1 , 2]. Is there a way to do this with my query directly? Or do I need to flatten my array after I get my results?

Edit : If I remove rowMode: array, I get an array of javascript objects : [anonymous { id: 1 }, anonymous { id: 2 }], which doesn't give me what I need.

TommyBs · Accepted Answer · 2019-08-09 13:02:56Z

1

If you use a rowMode of 'Array' it will return each row as an individual array as per the docs https://node-postgres.com/features/queries#Query%20config%20object . The default is to return each one as an object, so just remove the rowMode:"array" line and see if that works.

With the object you can use map or the array you can use a simple flatMap on your original results

let results = result.flatMap(row => row); // for the array or array results
let results = result.map(item => item.id); // for the object results

edited Aug 9, 2019 at 13:02

answered Aug 9, 2019 at 12:51

TommyBs

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2 Comments

Jbert Over a year ago

If I remove rowMode: array, I get an array of javascript objects : [ anonymous { id: 1 }, anonymous { id: 2 } ]

TommyBs Over a year ago

Well it's either going to return an array of objects or an array of arrays, so it comes down to what you prefer working with

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