PragProg Customers

Web Development with Clojure, Third Edition: (create-migration "guestbook") not working (page 9)

simonpeter

simonpeter

Web Development with Clojure, Third Edition: (create-migration "guestbook") not working (page 9)

When I try the command to create a pair of migration files I get an error.

user=> (create-migration "guestbook")
Execution error (IllegalArgumentException) at user/create-migration (user.clj:61).
find not supported on type: mount.core.DerefableState

user=>

Linux Ubuntu 20.04 LTS, OpenJDK 14.0.2

4 comments
#errata/book-web-development-with-clojure-third-edition
5 1782 4

Marked As Solved

bishax

bishax

This is probably because you haven’t mounted the DB by starting the app.

(in-ns 'guestbook.user)
(start)
(create-migration "foo")
1
Post #2

Also Liked

simonpeter

simonpeter

Thank you, I tried that and it worked.

Hopefully that can be added to the instructions in the book so that people like me who are learning Clojure as they are learning how to make web apps using it can be less confused.

2
Post #3
bmads_51

bmads_51

Dmitri Sotnikov @dmitri and Scot Brown @svmbrown

Working through this now and encountered same issue, so thanks for this thread!

In addition, I found on p. 9

A common beginner error that you may encounter is forgetting to start the
database connection. If you do get this error, don’t worry—just run (start) and try again. In fact, any error that mentions mount.core.DerefableState is probably due to forgetting to run (start).

But I agree. There should be an additional sentence telling the reader to not only start the REPL (which it does) but to also ‘(start)’ especially since we are a long way from p. 9!

1
Post #4

Where Next?

View thread on forum
View Web Development With Clojure Third Edition's book portal
Post errata for this book
Post a suggestion for this book
Post a question about this book
Post a review about this book
Home PragProg Customers
#errata/book-web-development-with-clojure-third-edition
5 1782 4
Last post

Popular Pragmatic Bookshelf topics Top

johnp
PragProg Customers

Python Testing with Pytest: Tasks sample code tinydb api change
Hi Brian, Looks like the api for tinydb has changed a little. Noticed while working on chapter 7 that the .purge() call to the db throws...
#errata/book-python-testing-with-pytest
4 1231 1
New
herminiotorres
PragProg Customers

Concurrent Data Processing in Elixir: various errata
Hi @Margaret , On page VII the book tells us the example and snippets will be all using Elixir version 1.11 But on page 3 almost the en...
#errata/book-concurrent-data-processing-in-elixir
15 1544 13
New
frasette
PragProg Customers

A Common-Sense Guide to Data Structures and Algorithms, Second Edition: erroneous extra space complexity (page400)
A Common-Sense Guide to Data Structures and Algorithms, Second Edition by Jay Wengrow @jaywengrow Hi, I have the paperback version of t...
#errata/book-a-common-sense-guide-to-data-structures-and-algorithms-second-edition
4 1180 2
New
jskubick
PragProg Customers

Kotlin and Android Development featuring Jetpack: SwitchCompat's thumbTint and trackTint being ignored (page 76)
I think I might have found a problem involving SwitchCompat, thumbTint, and trackTint. As entered, the SwitchCompat changes color to hol...
#errata/book-kotlin-and-android-development-featuring-jetpack
0 2702 2
New
jskubick
PragProg Customers

Kotlin and Android Development featuring Jetpack: Error in generated Game.java (page 136)
I’m under the impression that when the reader gets to page 136 (“View Data with the Database Inspector”), the code SHOULD be able to buil...
#question/book-kotlin-and-android-development-featuring-jetpack
2 1166 8
New
digitalbias
PragProg Customers

Build a Weather Station with Elixir and Nerves: Problem connecting to Postgres with Grafana
Title: Build a Weather Station with Elixir and Nerves: Problem connecting to Postgres with Grafana on (page 64) If you follow the defau...
#errata/book-build-a-weather-station-with-elixir-and-nerves
0 1958 4
New
brunogirin
PragProg Customers

Python Testing with pytest, Second Edition: error when running tox in parallel (page 151)
When trying to run tox in parallel as explained on page 151, I got the following error: tox: error: argument -p/–parallel: expected one...
#errata/book-python-testing-with-pytest-second-edition
0 1108 1
New
adamwoolhether
PragProg Customers

Powerful Command-Line Applications in Go: Exercise Solutions (many pages)
Is there any place where we can discuss the solutions to some of the exercises? I can figure most of them out, but am having trouble with...
#question/book-powerful-command-line-applications-in-go
17 1377 9
New
dtonhofer
PragProg Customers

The Definitive ANTLR 4 Reference - "Java.g4" grammer (used on page 40) no longer passes ANTLR
@parrt In the context of Chapter 4.3, the grammar Java.g4, meant to parse Java 6 compilation units, no longer passes ANTLR (currently 4....
#errata/book-the-definitive-antlr-4-reference
0 1012 3
New
mcpierce
PragProg Customers

Kotlin and Android Development featuring Jetpack: Unique constraint error when running chapter 5 code changes
@mfazio23 I’ve applied the changes from Chapter 5 of the book and everything builds correctly and runs. But, when I try to start a game,...
/book-kotlin-and-android-development-featuring-jetpack
0 1165 10
New

Other popular topics Top

PragmaticBookshelf
General Dev>Learning Resources

A Common-Sense Guide to Data Structures and Algorithms, Second Edition
Algorithms and data structures are much more than abstract concepts. Mastering them enables you to write code that runs faster and more e...
pragprog.com
#pragprog/python/ruby#published-book/book-a-common-sense-guide-to-data-structures-and-algorithms-second-edition#math#algorithms/js
19 4751 5
New
siddhant3030
General Dev>Dev Chat

Which vertical monitor do you use?
I’m thinking of buying a monitor that I can rotate to use as a vertical monitor? Also, I want to know if someone is using it for program...
#monitors#programming
51 4622 20
New
brentjanderson
General Dev>Hardware

Moonlander Keyboard (Mechanical) (Ergonomic) (Split) (Ortholinear)
Bought the Moonlander mechanical keyboard. Cherry Brown MX switches. Arms and wrists have been hurting enough that it’s time I did someth...
#hardware/keyboards#moonlander#mechanical-keyboards#ortholinear#ergonomic
212 16447 90
New
AstonJ
General Dev>Code Editors

Poll: Which code editor do you use?
You might be thinking we should just ask who’s not using VSCode :joy: however there are some new additions in the space that might give V...
#community#polls/vim/emacs#code-editors/vscode#notepad/sublime-text#atom/textmate#codespaces#brackets/onivim#geany
121 5409 61
New
AstonJ
General Dev>Hardware

Seen any cool new keyboards?
We have a thread about the keyboards we have, but what about nice keyboards we come across that we want? If you have seen any that look n...
/keyboards#mechanical-keyboards
49 5587 39
New
AstonJ
General Dev>Hardware

Custom keyboard keycaps
There’s a whole world of custom keycaps out there that I didn’t know existed! Check out all of our Keycaps threads here: https://forum....
#hardware/keyboards#keycaps#mechanical-keyboards
15 9736 19
New
AstonJ
General Dev>Hardware

Keyboard thock (sound)
I’ve been hearing quite a lot of comments relating to the sound of a keyboard, with one of the most desirable of these called ‘thock’, he...
/keyboards#mechanical-keyboards
14 9747 8
New
PragmaticBookshelf
Frontend>Learning Resources

Modern CSS with Tailwind
Tailwind CSS is an exciting new CSS framework that allows you to design your site by composing simple utility classes to create complex e...
pragprog.com
#pragprog/tailwind#published-book/book-modern-css-with-tailwind
12 4724 4
New
Margaret
General Dev>Sales

Get 50% off these PragProg books during our Think Again Sale
Think Again 50% Off Sale » The theme of this sale is new perspectives on familiar topics. Enter coupon code ThinkAgain2021 at checkout t...
#community#pragprog/elixir/book-a-common-sense-guide-to-data-structures-and-algorithms-second-edition/book-programming-machine-learning/book-the-ray-tracer-challenge/book-forge-your-future-with-open-source/book-software-design-x-rays#algorithms/book-testing-elixir#machine-learning#sale/book-concurrent-data-processing-in-elixir/book-intuitive-python
8 6210 2
New
DevotionGeo
General Dev>Questions

Do you prefer regular mechanical keyboards or low profile mechanical keyboards and why?
I have always used antique keyboards like Cherry MX 1800 or Cherry MX 8100 and almost always have modified the switches in some way, like...
/keyboards#mechanical-keyboards
27 3339 9
New
Back to top

Latest in Web Development with Clojure, Third Edition

Web Development with Clojure, Third Edition Portal ❯

PragProg Customers

Pragmatic Bookshelf PragProg Customers ❯

Latest on Devtalk

Devtalk ❯

We ❤️ helpful members!

We reward our most helpful members via our MOTM scheme - by giving away a whopping 25 books per year!

Member of the Month

Devtalk Sponsors

Pragmatic Bookshelf

Practical resources that improve the lives of professional developers.

Erlang Solutions

We build trusted fault-tolerant systems that scale to billions of users.

Honeybadger

Real-time error tracking, performance insights, and observability for devs.

EEF

Supporting innovation across the BEAM ecosystem.

coders51

We build reliable cloud platforms for business-critical systems.

Manning Publications

Develop your skills with books, videos, and courses.

AppSignal

Catch errors, track performance, monitor hosts and more.

WyeWorks

Enabling companies to succeed by building software people love.

Pragmatic Studio

Courses that move you from confusion to "Aha, now I get it!"

View all our sponsors ❯

Categories:

Sub Categories:

Popular Portals

Devtalk Sponsors

Pragmatic Bookshelf

Practical resources that improve the lives of professional developers.

Erlang Solutions

We build trusted fault-tolerant systems that scale to billions of users.

Honeybadger

Real-time error tracking, performance insights, and observability for devs.

EEF

Supporting innovation across the BEAM ecosystem.

coders51

We build reliable cloud platforms for business-critical systems.

Manning Publications

Develop your skills with books, videos, and courses.

AppSignal

Catch errors, track performance, monitor hosts and more.

WyeWorks

Enabling companies to succeed by building software people love.

Pragmatic Studio

Courses that move you from confusion to "Aha, now I get it!"

View all our sponsors ❯

We're in Beta

About us Mission Statement See our Roadmap