Core Java

Better dealing with “Could not find property X on plugin Y” in Gradle 2.13

Missing username, password or token to a service you may have never heard of? It usually happens when you try to do anything (like just build a project) not only when a given plugin (like an online code coverage tool) is used. I didn’t like to have to modify my environment to just provide a small fix to another open source project. It was annoying me and I wanted to change it. Starting with Gradle 2.13 it became possible. However, let’s start with the reasons (if you are interested only in the solution please move forward to the last 2 paragraphs).


Why do I get “Could not find property…”?

Most of Gradle plugins need to be configured. Some properties can be set directly in build.gradle, but some others (especially credentials) are better to keep locally in ~/.gradle/ As a result, a plugin configuration sections often look like this:

bintray {
    user = project.getProperty('bintrayUser')
    key = project.getProperty('bintrayKey')

or that:

bintray {
    user = getProperty('bintrayUser')
    key = getProperty('bintrayKey')

or even shorter:

bintray {
    user = bintrayUser
    key = bintrayKey

It works fine for a project developer having bintrayUser and bintrayKey defined in its local configuration, but for every person not uploading to Bintray on their daily basis it fails with:

* What went wrong:
A problem occurred evaluating root project 'another-nice-open-source-project'.
> Could not find property 'bintrayKey' on com.jfrog.bintray.gradle.BintrayExtension_Decorated@2ecc563.

The result is that project.getProperty(), not to mentioned explicit assignment, just throws exception when a particular property is not found. The bad is that the code is executed in the configuration phrase. For that reason the execution of every task, even not related to that particular plugin (like gw tasks or gw wrapper) fails miserably.

As a workaround a guard check has to be performed:

bintray {    //Gradle <2.13
    user = hasProperty('bintrayUser') ? getProperty('bintrayUser') : ''
    key = hasProperty('bintrayKey') ? getProperty('bintrayKey') : ''

It doesn’t look good very compact. As an another option a dummy placeholder could be kept in project configuration, but starting with Gradle 2.13 there is a better way to cope with that.


Gradle 2.13 is the first version with my contribution of the new method project.findProperty(). It behaves the same as getProperty(), but instead of throwing an exception the null value is returned. This simplifies the assignment greatly:

bintray {    //Gradle 2.13+
    user = findProperty('bintrayUser') ?: ''
    key = findProperty('bintrayKey') ?: ''

Some people could say that Optional could be better as a returned value, but this is an API and Gradle supports Java older than 8.


For me findProperty is a method I’ve been very often looking for in Gradle. I regret that it took me over the year to make this pull request. Gradle 2.13 has been just released and version upgrades across projects will be performed gradually. It can take some time, but every project migrating to 2.13 will be able to simplify its configuration making the “Could not find property X on plugin Y” error message a remembrance of the past (of course unless you really need to configure particular plugin to use it).

Tested with Gradle 2.13.

Marcin Zajaczkowski

Marcin is an experienced architect who specializes in creating high quality software. Being under the impression of the Agile methodologies and the Software Craftsmanship movement, he believes in the value of good, testable and maintainable code. He aims to forge good software that makes the client delighted and the team proud of how the code itself looks.In his teaching, as a conference speaker, college lecturer, IT coach and trainer, he shows how to guide software development effectively using tests (with TDD, pair programming, Clean Code, design patterns, etc.) and maintaining a quality-oriented development environment (with CI, Sonar, automatic deployment, etc.).He is also a FOSS projects author and contributor, a Linux enthusiast.
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