unable to resolve Maven dependency placeholder reference value - maven

my project has dependencies on some framework jars:
<groupId>my-compamy</groupId>
<artifactId>my-project</artifactId>
<version>1.0</version>
<dependency>
<groupId>my-company</groupId>
<artifactId>child-jar1</artifactId>
<version>2.0</version>
</dependency>
recently the framework team changed their packaging, in the repository, they put a parent pom (used to be separated child jars) like this:
<properties>
<reivison>2.0</revision>
</properties>
<groupId>my-company</groupId>
<artifactId>framework-parent</artifactId>
<packaging>pom</packaging>
<version>${revision}</version>
<modules>
<module>child-jar1</module>
</modules>
in the child-jar1 pom:
<parent>
<artifactId>framework-parent</artifactId>
<groupId>my-company</groupId>
<version>${revision}</version> <!-- can find the value! -->
</parent>
<artifactId>child-jar1</artifactId>
<packaging>jar</packaging>
When I build my-project, I got error message like:
... Failed to collect dependencies at my-company:child-jar1:jar:2.0.
... cuased by: could not find framework-parent:pom ${revision}
and the child-jars are not downloaded.
it looks that it is the placeholder in the child pom caused the problem: my-project could not resolve the placeholder value in the dependent(chiild-jar1)'s pom.
tried multiple approaches to resolve the referenced value from my-project side but nothing worked. Can this be resolved from my-project side without altering any dependency framework's setting? Please help.

There is a way to replace the palceholder with concrete value: add flatten-maven-plugin in the framework parent pom file build section (first to run) - this does not impact the framework's functionality but has to be done in the framework side. I gave this suggestion to the framework owner and they took it. It works.
Thanks to all comment providers!

Related

Can modules referring to parent pom by relative path be depended on by 3rd parties?

I have a parent module, which defines its version as follows:
<groupId>org.group</groupId>
<artifactId>parent-id</artifactId>
<packaging>pom</packaging>
<version>${library.version}</version>
<properties>
<library.version>1.0.0</library.version>
</properties>
Then I have a sub module, which points to its parent as follows:
<parent>
<groupId>org.group</groupId>
<artifactId>parent-id</artifactId>
<version>${library.version}</version>
<relativePath>../../</relativePath>
</parent>
<artifactId>child-id</artifactId>
<packaging>jar</packaging>
And I depend on it in my other projects like so:
<dependency>
<groupId>org.group</groupId>
<artifactId>child-id</artifactId>
<version>1.0.0</version>
</dependency>
This results in the following error for me:
Failed to read artifact descriptor for org.group:child-id:1.0.0: Failure to find org.group:parent-id:pom:${library.version}
Can this problem be solved without resorting to mvn versions:set in my multi module project to manage explicit versions in all poms?
/edit: currently solved this problem with a workaround that makes using mvn versions:set a little easier.

Maven can't get access to parent properties

I have following structure:
parent-pom (pom)
|
- base-component (with <parent> parent-pom </parent>)(pom)
|
-- child-component (with <parent> base-component </parent>)(jar)
-- some-folder/another-child (with <parent> base-component </parent>)(jar)
In parent-pom I have properties with versions like
<properties>
<product-version>3.7.8</product-version>
</properties>
When I build child-component and use there ${product-version} - it is built without errors.
But when I trying to build another-child(with child-component as dependency) - maven can't read ${product-version} or throws an error Could not find artifact base-component even if I set <relativePath>.
I think the problem is folder between base-component and another-child, but I can't move it to level up.
Any ideas?
Make sure that the relative path is set correctly in the another-child module. Since it's under another directory, its parent base-component should be up by two directories:
<parent>
<groupId>...</groupId>
<artifactId>base-component</artifactId>
<version>...</version>
<relativePath>../../pom.xml</relativePath>
</parent>
Also make sure that in the base-component project, the module definition includes the additional path for another-child, so it should be something like:
<modules>
<module>child-component</module>
<module>some-folder/another-child</module>
</modules>
Before building another-child (or any other sub-module), try to build (mvn install) the whole project, starting at the root parent.
Try setting on the pom the project directory.
Parent:
<properties>
<main.basedir>${project.basedir}</main.basedir>
</properties>
Sibbling/children:
<properties>
<main.basedir>${project.parent.basedir}</main.basedir>
</properties>
children/ grandchildren:
<properties>
<main.basedir>${project.parent.parent.basedir}</main.basedir>
</properties>

Generating the .war file from maven dependency project

Here I have two projects those are project(1) and project(2).
I am going to generate a .war file for the project(1) but it depends on project(2).
I built the project(2) as a .jar file and added it to the project(1)'s build path but while runnig mvn install it results in compilation errors like:
package com.disha.db.dao.orm.gen does not exist` the package is in the project(2).
Can any one please help to me.
You have to delegate dependency management to Maven and that's actually where it comes in hand, otherwise you can move on packaging and resolving inter-projects dependencies by hand and let the Maven alternative be dropped.
You should make sure you have provided the correct Project Object Module description for your projects (pom.xm) along with tha packaging type.
Then since you want the project(2) to be availble for project(1) at compilation time, you have to declare, project(2) as a dependency of project(1).
project(2) pom.xml (I will refer to it as project-2 since 'project(2)' does not match a valid id pattern.):
<project>
<modelVersion>4.0.0</modelVersion>
<groupId>project2.group.id</groupId>
<artifactId>project-2</artifactId>
<version>1.0</version>
<packaging>jar</packaging>
</project>
Now the project(1) will refer to the project-2 artifact as a dependency with scope compile:
<project>
<modelVersion>4.0.0</modelVersion>
<groupId>project1.group.id</groupId>
<artifactId>project-1</artifactId>
<version>1.0</version>
<packaging>war</packaging>
<dependencies>
<dependency>
<groupId>project2.group.id</groupId>
<artifactId>project-2</artifactId>
<version>1.0</version>
</dependency>
</dependencies>
</project>
Note: Update the group and artifact IDs with ones you are using.

Maven version not getting updated in the .POM file

I am using Maven for building my code. I created module based maven structure like below
Parent-POM
Sub-Parent1
SP1_Child1
SP1_Child2
SP1_Child3
Sub-Parent2
SP2_Child1
SP2_Child2
SP2_Child3
All my module versions, and external dependency versions are maintained in the Parent POM. Everything works fine when I do a complete mvn install, but when I try to build one sub module like SP1_Child1, then the build fails, because it is not able to identify the version of its dependencies. I checked the maven repository in my local machine, and all my modules were installed, but the .POM files do not have the version numbers. This is probably because the where the mvn install on the Parent POM is not replacing the ${module.version} with the actual version for the child modules.
Parent-POM
<project ..>
<groupId>the.company.project</groupId>
<artifactId>Parent-POM</artifactId>
<version>1.0-SNAPSHOT</version>
...
<properties>
<module.version>1.0</module.version>
</properties>
</project>
SP1_Child1
<project ..>
<parent>
...
</parent>
<groupId>the.company.project</groupId>
<artifactId>SP1_Child1</artifactId>
<version>${module.version}</version>
...
</project>
How how can my mvn install update the versions in the .POM files in the maven repository? Or how can I run one of my sub-modules without any version errors?
The default layout of a child pom should look like this.
<project ..>
<parent>
<groupId>the.company.project</groupId>
<artifactId>SP1_Child1</artifactId>
<version>1.0-SNAPSHOT</version>
</parent>
<groupId>the.company.project</groupId>
<artifactId>SP1_Child1</artifactId>
...
</project>
But you child should not define version separately only in the parent element without using a property. The version is automatically inherited to the child module from the parent. If you have the same group you also don't need to define the group in child. You can use it like this:
<project ..>
<parent>
<groupId>the.company.project</groupId>
<artifactId>SP1_Child1</artifactId>
<version>1.0-SNAPSHOT</version>
</parent>
<artifactId>SP1_Child1</artifactId>
...
</project>
Taking the SP1_Child1 version from parent will be very annoying for you because it will force you to install a new version of the parent for any new version of the SP1_Child1 project.
There are 2 different possible situations :
You want to be able to manage different project, with different lifecycles.
Then you specify a version in the SP1_Child1 project, and you specify the version of SP1_Child1 to be used by other projects in the parent POM (in this case, the 2 values can be different).
Your application is monolithic, even if it is organized in different modules for convenience. Then in this case, the best is to do what khmarbaise advises, keep one version for all your projects, and inherit the version from the parent.

Warning on using project.parent.version as the version of a module in Maven 3

In maven multi-module projects where I want each of the modules to always keep the same version as the parent, I've typically done something like the following in the module's pom.xml:
<parent>
<groupId>com.groupId</groupId>
<artifactId>parentArtifactId</artifactId>
<version>1.1-SNAPSHOT</version>
</parent>
<groupId>com.groupId</groupId>
<artifactId>artifactId</artifactId>
<packaging>jar</packaging>
<version>${project.parent.version}</version>
<name>name</name>
Since I started using maven 3.0-alpha-5, I get the following warning for doing so.
[WARNING]
[WARNING] Some problems were encountered while building the effective model for com.groupid.artifactId:name:jar:1.1-SNAPSHOT
[WARNING] 'version' contains an expression but should be a constant. # com.groupid.artifactId:name::${project.parent.version}, /Users/whaley/path/to/project/child/pom.xml
[WARNING]
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING]
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
[WARNING]
I'm curious to know what the real problem with tying a module's version to the parent version is, if any? Or is this a case of a general warning when any expression, regardless of whether it's project.parent.version, is used for the version element.
I'm curious to know what the real problem with tying a module's version to the parent version is, if any? Or is this a case of a general warning when any expression, regardless of whether it's project.parent.version, is used for the version element.
Well, that would be easy to test. Because I was curious, I just did it for you using the following pom:
<project>
<modelVersion>4.0.0</modelVersion>
<parent>
<artifactId>parent</artifactId>
<groupId>com.mycompany</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<groupId>com.mycompany</groupId>
<artifactId>module</artifactId>
<version>${myversion}</version>
<name>module</name>
<url>http://maven.apache.org</url>
<properties>
<myversion>1.0-SNAPSHOT</myversion>
</properties>
...
</project>
And maven is indeed complaining:
[WARNING] 'version' contains an expression but should be a constant. # com.mycompany:module:${myversion}, /home/pascal/Projects/maven-maven3-testcase/module/pom.xml
To be honest, I think that maven is right here, it doesn't make much sense to use a property for the <version> element (at least not for project.version) and it's nice to have maven complaining about it.
And if you want to use the parent pom version in sub-modules, just remove the <version> tag from the child poms, they will inherit the version from the parent. What you are currently doing is unnecessary.
I might be late here to discuss on this. I got a simple solution for this WARNING.
First of all, if you want that all child modules will take same version as parent, then you just remove <version> tag from child POM and as you include <parent> in child POM, that should be there.
In absence of <version> in child POM, it will automatically take Parent POM version.
Now if you want to use property in parent POM version and want to get the same in all child-modules, you can go through as follow.
There is no limitation on using property in <version> part of parent or child POM. But if you use your own xml tag for specifying that or you use your own property, then WARNING comes, (although this is just warning, everything works as expected).
But if you want to get rid of this WARNING, you can follow these steps:
Create <properties> inside POM.xml as below
<properties>
<revision>1.0.0</revision> <!-- Put your version -->
</properties>
In <version> of the POM.xml, put as follow
<version>${revision}</version>
Sample code snippet (for multi-module project):
<groupId>abc.xyz</groupId>
<artifactId>pqr</artifactId>
<!-- <version>1.0.0</version> -->
<version>${revision}</version>
<packaging>pom</packaging>
<description>Parent POM</description>
<properties>
<revision>1.0.0</revision>
</properties>
Note: Instead of <revision>, if you use any other name (for example, <my.version>), you will face that WARNING
Now if you want to pass version during mvn deploy, you can use mvn deploy "-Drevision=1.0.0-SNAPSHOT" and similarly for mvn install also.
Now if above configuration, you want to use as Parent POM, and you want to use same version in all child module, that can also be done. In each child module POM, use below
<parent>
<groupId>abc.xyz</groupId>
<artifactId>Parent</artifactId>
<!-- <version>1.0.0</version> -->
<version>${revision}</version>
</parent>
<groupId>abc.xyz</groupId>
<artifactId>Child</artifactId>
<!-- <version>1.0.0</version> --> <!-- Automatically inherit parent POM version -->
<name>Demo</name>
For reference, you can go through maven multi module setup
It seems that the warning is correct. See MNG-4717: "the pom that gets deployed will not have the property value resolved, so
anyone depending on that pom will pick up the dependency as being the
string uninterpolated with the ${ } and much hilarity will ensue in your
build process." "However, if one uses flatten-maven-plugin the deployed pom gets a resolved value."

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