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nthu-stage / back-end

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db hint #73

Open vitaly-t opened 7 years ago

vitaly-t commented 7 years ago

looking at this code: https://github.com/nthu-stage/back-end/blob/master/src/model/workshops.js

you are misusing method sequence. The method is there for processing infinite/dynamic sequences, it is not for handling 1-2-3 step logic, which can easily be done within task/transaction on its own.

It's just quite inefficient.

yun-cloud commented 7 years ago

Didn't notice that sequence is for processing a dynamic sequence. Still trying to rewrite it~~~. Thank you for your suggestion. Very appreciate it🙂

BTW, could I ask you 1 question? when I tries to do some sql, like WHERE column IN $(dynamic_array), How should I to do this?

My current solutions is

function query_values (datas) {
    //! sql = "... WHERE column IN $(col:raw)"
    //! db.any(sql, {col: query_values(datas)});

    if (datas.length === 0) {
        return '(NULL)';
    }
    let values = {};
    for (let data of datas) {
        values[data.toString()] = data;
    }
    return pgp.helpers.values(values);
}

But seems that pgp.helper.values method is not for this situation(?!

vitaly-t commented 7 years ago

See my answer here: https://stackoverflow.com/questions/10720420/node-postgres-how-to-execute-where-col-in-dynamic-value-list-query

Basically, you use the WHERE column IN $(dynamic_array:csv) syntax, passing an array of values for dynamic_array :wink: