God, it's impossible! You just have to convert the entire fucking call stack all the way up to async functions. It could mean refactoring hundreds of functions.
To be fair, there is a logic to this, if you put yourself within the crappiness of the JavaScript threading model. And Python is not that much better with its Global Interpreter Lock.
The problem is that async was introduced relatively late, previously we just had to use infinitely deep callback trees, which was worse:compared to the new infinitely more readable:But now we are in an endless period of transition between both worlds.
myAsync().then(ret => myAsync2(ret).then(ret2 => myAsync3(re3)))ret = await myAsync()
ret2 = await myAsync2(ret)
ret3 = await myAsync3(ret3)It is also worth mentioning that callbacks are still inescapable if you really want to fan out into a non-linear dependency graph, usually with
Promise.all:await Promise.all([
myAsync(1).then(ret => myAsync2(ret)),
myAsync(2).then(ret => myAsync2(ret)),
])Bibliography:
- stackoverflow.com/questions/21819858/how-to-wrap-async-function-calls-into-a-sync-function-in-node-js-or-javascript
- stackoverflow.com/questions/9121902/call-an-asynchronous-javascript-function-synchronously
- stackoverflow.com/questions/47227550/using-await-inside-non-async-function
- stackoverflow.com/questions/43832490/is-it-possible-to-use-await-without-async-in-js
- stackoverflow.com/questions/6921895/synchronous-delay-in-code-execution
And then, after many many hours of this work, you might notice that the new code is way, way way slower than before, because making small functions
async has a large performance impact: madelinemiller.dev/blog/javascript-promise-overhead/. Real world case with a 4x slowdown: github.com/ourbigbook/ourbigbook/tree/async-slow.Anyways, since you Googled here, you might as well learn the standard pattern to convert callbacks functions into async functions using a promise: stackoverflow.com/questions/4708787/get-password-from-input-using-node-js/71868483#71868483
WellSync, if you are gonna useSync this wonky language thing inSync one place, you might as well useSync it everywhereSync and make it more decent. See also: how to convert
async to sync in JavaScript.Their CLI debugger is a bit crap compared to GDB, basic functionality is either lacking or too verbose:Documentation at: nodejs.org/dist/latest-v16.x/docs/api/debugger.html
- stackoverflow.com/questions/65493221/how-to-break-at-a-specific-function-or-line-with-the-node-js-node-inspect-comman
- stackoverflow.com/questions/70486188/how-to-break-on-uncaught-exception-on-the-node-js-node-inspect-command-line-debu Some operations are only possible on the browser debug UI...
- foreign keys are capitalized:
- you must give
foreignKeywhen using aliases, otherwise it fails subtely. That would be derived automatically. - stackoverflow.com/questions/41502699/return-flat-object-from-sequelize-with-association can't auto-flatten to reuse the database's
ORDER limitandoffsetdon't work withoutsubQuery: falsewhen doing includes! It is just too buggy. Examples of this can be found e.g. under nodejs/sequelize/many_to_many_same_model.js.- stackoverflow.com/questions/34059081/how-do-i-reference-an-association-when-creating-a-row-in-sequelize-without-assum hard to not duplicate foreign keys values everywhere
- stack traces permanently broken or requiring non-obvious configs:
- does not automatically update fields on hooks: github.com/sequelize/sequelize/issues/8586#issuecomment-422877555
- cannot change columns when other columns have constraints due to the backup table?
- you have to use
.get()forattributealiased fields, why? stackoverflow.com/questions/32649218/how-do-i-select-a-column-using-an-alias/69890944#69890944 .idgets added toSELECTno matter what, breakingGROUP BYunless you do horrible workarounds:- no simple built-in mechanism for transaction retries: Sequelize transaction retries
- impossible to do subqueries in general. Docs just tell you to use literals. This in particular prevents single query deletes with join as done at nodejs/sequelize/raw/many_to_many.js:Also, you can't get query strings either: github.com/sequelize/sequelize/issues/2325
- sequelize.org/master/manual/sub-queries.html: the docs actually just tell you to use literals, lol
- stackoverflow.com/questions/45354001/nodejs-sequelize-delete-with-nested-select-query
- migrations. Generally speaking, anything but the simplest migrations are exceedingly hard to get right, as you have to go very low level when doing migrations. Syntax can be very different from regular DB operations.
- no way to do (non-raw) queries during migrations, e.g. to update fields based on other fields in a complex way?
- github.com/sequelize/cli/issues/862
- stackoverflow.com/questions/18742962/add-data-in-sequelize-migration-script
- stackoverflow.com/questions/38671483/sequelize-migration-update-model-after-updating-column-attributes
- stackoverflow.com/questions/38998397/can-i-use-sequelize-models-in-migration-scripts
- stackoverflow.com/questions/45286429/custom-query-on-sequelize-seeder
queryInterface.sequelize.modelscontains onlySequelizeMeta. Not sure why they have this limitation. - stackoverflow.com/questions/56043246/node-js-sequelize-no-primary-keys-when-migrating/56046101#56046101
- SQLite
changeColumnmigrations do on delete cascades of other tables. SQLite does not have change column statements, so they have to drop and recreate tables, but they don't temporarily remove cascades, so you lose data: stackoverflow.com/questions/62667269/sequelize-js-how-do-we-change-column-type-in-migration/70486686#70486686 - associations require full explicit index construction: stackoverflow.com/questions/39651853/how-to-create-join-table-with-foreign-keys-with-sequelize-or-sequelize-cli
- ability to iterate over a large result without blowing up memory and without using limit + offset (which is inneficient e.g. when looping over recursive queries). This is also known as cursor or streaming interfaces:E.g. the Python SQLite interface supports this just fine: stackoverflow.com/questions/29582736/python3-is-there-a-way-to-iterate-row-by-row-over-a-very-large-sqlite-table-wi
- stack overflow
- stackoverflow.com/questions/28787889/how-can-i-set-up-sequelize-js-to-stream-data-instead-of-a-promise-callback
- stackoverflow.com/questions/43964067/how-to-implement-cursor-pagination-using-sequelize
- stackoverflow.com/questions/57164242/perform-sequelize-findall-in-a-huge-array
- stackoverflow.com/questions/55191891/how-to-loop-through-result-in-sequelize generic loop
- issue tracker
- stack overflow
- empty
attributes: []breaks some nested queries: github.com/sequelize/sequelize/issues/16436 - does not expose a iteration API that supports large arrays?E.g. Python SQLite does: stackoverflow.com/questions/29582736/python3-is-there-a-way-to-iterate-row-by-row-over-a-very-large-sqlite-table-wi
Exampes under nodejs/sequelize/raw:
- nodejs/sequelize/raw/index.js: Sequelize raw query hello world. Ideally one should never use a raw query in a real project. We use raw examples mostly as a SQL tutorial under SQL example, and will not comment on them much further on this section.
No support:
Example with raw examples under nodejs/sequelize/raw/many_to_many.js
This example is the same as nodejs/sequelize/raw/parallel_select_and_update.js, but going through Sequelize rather than with Sequelize raw queries.
NONE is not supported for now to not have a transaction at all because lazy.The examples illustrates: stackoverflow.com/questions/55452441/for-share-and-for-update-statements-in-sequelize
Sample invocation:where:
node --unhandled-rejections=strict ./parallel_select_and_update.js p 10 100 READ_COMMITTED UPDATEREAD_COMMITTED: one of the keys documented at: sequelize.org/master/class/lib/transaction.js~Transaction.html which correspond to the standard sQL isolation levels. It not given, don't set one, defaulting to the database's/sequelize's default level.UPDATE: one of the keys documented at: sequelize.org/master/class/lib/transaction.js~Transaction.html#static-get-LOCK. Update generates aSELECT FOR UPDATEin PostgreSQL for example. If not given, don't use anyFOR xxxexplicit locking.
Other examples:
node --unhandled-rejections=strict ./parallel_select_and_update.js p 10 100 READ_COMMITTED UPDATE
Then, the outcome is exactly as described at: nodejs/sequelize/raw/parallel_select_and_update.js:
READ_COMMITTED: failsREAD_COMMITTED UPDATE: works- This case also illustrates Sequelize transaction retries, since in this transaction isolation level transactions may fail:
Transaction retries are inevitable, as some sQL isolation levels
Doesn't seem to have any simple built-in mechanism?
Example: nodejs/sequelize/trigger_count.js
There is of course no built-in support for SQL TRIGGERs in Sequelize, but we can add our own: stackoverflow.com/questions/29716346/how-to-create-a-trigger-in-sequelize-nodejs/76215728#76215728
This doesn't do a hole lot. Ciro Santilli wouldn't really call it a web framework. It's more like a middleware. Real web frameworks are built on top of it.
Examples under: nodejs/express:
- nodejs/express/min.js: minimal example. Visit localhost:3000 and it shows
hello world. It is a bit wrong because the headers say HTML but we return plaintext. - nodejs/express/index.js: example dump with automated tests where possible. The automated tests are run at startup after the server launches. Then the server keeps running so you can interact with it.
Pinned article: Introduction to the OurBigBook Project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
. Source. We have two killer features:
- topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculusArticles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 3. Visual Studio Code extension installation.
Figure 4. Visual Studio Code extension tree navigation.
Figure 5. Web editor. You can also edit articles on the Web editor without installing anything locally.Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.Video 4. OurBigBook Visual Studio Code extension editing and navigation demo. Source. 
- Infinitely deep tables of contents:
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact