Author: John Au-Yeung

Web developer specializing in React, Vue, and front end development.

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Python Answers

How to set content type with Python Flask?

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Sometimes, we want to set content type with Python Flask.

In this article, we’ll look at how to set content type with Python Flask.

How to set content type with Python Flask?

To set content type with Python Flask, we can use the Response class.

For instance, we write

from flask import Response


@app.route("/ajax_ddl")
def ajax_ddl():
    xml = "foo"
    return Response(xml, mimetype="text/xml")

to create a Response object with the xml string as the body and the mimetype set to the MIME type of the response.

Conclusion

To set content type with Python Flask, we can use the Response class.

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Python Answers

How to fix ImportError: No module named MySQLdb with Python?

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Sometimes, we want to fix ImportError: No module named MySQLdb with Python.

In this article, we’ll look at how to fix ImportError: No module named MySQLdb with Python.

How to fix ImportError: No module named MySQLdb with Python?

To fix ImportError: No module named MySQLdb with Python, we install the pymysql package.

To install it, we run

pip install pymysql

Then we add a connection string with

SQLALCHEMY_DATABASE_URI = 'mysql+pymysql://.....'

Conclusion

To fix ImportError: No module named MySQLdb with Python, we install the pymysql package.

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JavaScript Answers

How to replace callbacks with promises in Node.js and JavaScript?

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Sometimes, we want to replace callbacks with promises in Node.js and JavaScript.

In this article, we’ll look at how to replace callbacks with promises in Node.js and JavaScript.

How to replace callbacks with promises in Node.js and JavaScript?

To replace callbacks with promises in Node.js and JavaScript, we can use the promisfy function from the util module.

For instance, we write

const { promisify } = require("util");
const glob = promisify(require("glob"));

app.get("/", async (req, res) => {
  const files = await glob("src/**/*-spec.js");
  res.render("template-test", { files });
});

to call promisify with the glob function we get from require("glob").

promisify returns a promise if we pass in anything that takes a standard Node.js async callback.

Therefore, we can use await with glob to get the resolve value from the promise.

Conclusion

To replace callbacks with promises in Node.js and JavaScript, we can use the promisfy function from the util module.

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JavaScript Answers

How to compare JavaScript Date objects?

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Sometimes, we want to compare JavaScript Date objects.

In this article, we’ll look at how to compare JavaScript Date objects.

How to compare JavaScript Date objects?

To compare JavaScript Date objects, we convert the dates to timestamps before we compare them.

For instance, we write

console.log(+startDate2 === +startDate3);
console.log(startDate2.getTime() === startDate3.getTime());
console.log(Number(startDate2) === Number(startDate3));

to use +, getTime or Number to convert the startDate2 and startDate3 date objects into timestamps in milliseconds before we compare them.

Timestamps are integers, so we can compare them with the === operator.

Conclusion

To compare JavaScript Date objects, we convert the dates to timestamps before we compare them.

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JavaScript Answers

How to parse date time string in dd.mm.yyyy format with JavaScript?

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Sometimes, we want to parse date time string in dd.mm.yyyy format with JavaScript.

In this article, we’ll look at how to parse date time string in dd.mm.yyyy format with JavaScript.

How to parse date time string in dd.mm.yyyy format with JavaScript?

To parse date time string in dd.mm.yyyy format with JavaScript, we can call the string split method.

For instance, we write

const strDate = "03.09.1979";
const [day, month, year] = strDate.split(".");
const date = new Date(+year, +month - 1, +day);

to call strDate.split to split the strDate string by the period.

Then we get the day, month, and year from the split string.

Next, we pass the 3 values into the Date constructor to create a date object from them.

We subtract month by 1 before we pass it into the Date constructor since it accepts a month that starts with 0 for January.

We use + to convert each value to a number before we pass them in as arguments.

Conclusion

To parse date time string in dd.mm.yyyy format with JavaScript, we can call the string split method.