'dependencies.dependency.version' 缺少错误，但版本在父级中管理

Question

I have a maven project that contains several modules. In Eclipse (Juno, with m2e) it seems to compile fine. But when I do a maven install on one of the modules, the build fails immediately.

Parent pom:

  <groupId>com.sw.system4</groupId>
  <artifactId>system4-parent</artifactId>
  <version>${system4.version}</version>
  <packaging>pom</packaging>
  <name>System 4 Parent Project</name>
  <modules>
    <module>system4-data</module>
     ...others...
  </modules>
  <properties>
    <system4.version>0.0.1-SNAPSHOT</system4.version>
    <spring.version>3.2.3.RELEASE</spring.version>
    ... others...
  </properties>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>${spring.version}</version>
        <scope>runtime</scope>
      </dependency>
    ... lots of others ...
    </dependencies>
  </dependencyManagement>

Child pom:

  <parent>
    <groupId>com.sw.system4</groupId>
    <artifactId>system4-parent</artifactId>
    <version>0.0.1-SNAPSHOT</version>
  </parent>
  <artifactId>system4-data</artifactId>
  <dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <scope>runtime</scope>
    </dependency>
    ... lots of others...
  </dependencies>

When I build, I get the following output:

[ERROR] The build could not read 1 project -> [Help 1]
[ERROR]
[ERROR]   The project com.sw.system4:system4-data:0.0.1-SNAPSHOT (C:\work\eclips
e_workspaces\systemiv\system4-parent\system4-data\pom.xml) has 8 errors

[ERROR]     'dependencies.dependency.version' for org.springframework:spring-cor
e:jar is missing. @ line 16, column 16

... others omitted for clarity ...

I dont understand why it doesn't even attempt to compile. Ive tried removing the runtime scope from parent and child, and it makes no difference. Please help!

Answer 1

如果有人在这里遇到与我相同的问题，我的问题是我缺少从子 pom.xml 复制的依赖项周围的<dependencyManagement>标记。

Answer 2

A couple things I think you could try:

1. Put the literal value of the version in the child pom

   <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>3.2.3.RELEASE</version> <scope>runtime</scope> </dependency>

2. Clear your .m2 cache normally located C:\Users\user.m2\repository. I would say I do this pretty frequently when I'm working in maven. Especially before committing so that I can be more confident CI will run. You don't have to nuke the folder every time, sometimes just your project packages and the .cache folder are enough.

3. Add a relativePath tag to your parent pom declaration

   <parent> <groupId>com.mycompany.app</groupId> <artifactId>my-app</artifactId> <version>1</version> <relativePath>../parent/pom.xml</relativePath> </parent>

It looks like you have 8 total errors in your poms. I would try to get some basic compilation running before adding the parent pom and properties.

Answer 3

Right, after a lot of hair tearing I have a compiling system.

Cleaning the .m2 cache was one thing that helped (thanks to Brian)

One of the mistakes I had made was to put 2 versions of each dependency in the parent pom dependencyManagement section - one with <scope>runtime</scope> and one without - this was to try and make eclipse happy (ie not show up rogue compile errors) as well as being able to run on the command line. This was just complicating matters, so I removed the runtime ones.

Explicitly setting the version of the parent seemed to work also (it's a shame that maven doesn't have more wide-ranging support for using properties like this!)

  <parent>
    <groupId>com.sw.system4</groupId>
    <artifactId>system4-parent</artifactId>
    <version>0.0.1-SNAPSHOT</version>
  </parent>

I was then getting weird 'failed to collect dependencies for' errors in the child module for all the dependencies, saying it couldn't locate the parent - even though it was set up the same as other modules which did compile.

I finally solved things by compiling from the parent pom instead of trying to compile each module individually. This told me of an error with a relatively simple fix in a different module, which strangely then made it all compile.

In other words, if you get maven errors relating to child module A, it may actually be a problem with unrelated child module Z, so look there. (and delete your cache)

Answer 4

In theory, maven does not allow to use a property to set a parent version.

In your case, maven can simply not figure out that the 0.0.1-SNAPSHOT version of your parent pom is the one that is currently in your project, and so it tries to find it in your local repo. It probably finds one since it is a snapshot, but it is an old version that probably not contains your Dependency Management section.

There is a workaround though :

Simply change the parent section in the child pom with this :

<parent>
    <groupId>com.sw.system4</groupId>
    <artifactId>system4-parent</artifactId>
    <version>${system4.version}</version>
    <relativePath>../pom.xml</relativePath>  <!-- this must match your parent pom location -->
</parent>

Answer 5

I had the same error, I forgot to add the child dependencies in the <dependencyManagement> . For example in the parent pom:

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.sw.system4</groupId>
            <artifactId>system4-data</artifactId><!-- child artifact id -->
            <version>${project.version}</version>
        <dependency>

        <!-- add all third party libraries ... -->

    </dependencies>
<dependencyManagement>

Answer 6

For those using the org.codehaus.mojo:flatten-maven-plugin : Be sure to set a flattenMode which keeps the dependencyManagement if you still want to import the pom (eg resolveCiFriendliesOnly ). Otherwise, the plugin will remove the dependencyManagement section.

Answer 7

确保子项目/父/版本节点中的值与其父项目/版本值匹配

Answer 8

在做子模块之前，您必须先构建父模块。

Answer 9

刚刚起作用的是删除 .m2 文件夹中的 settings.xml：该文件告诉项目寻找不存在的 spring mvc 和 web 版本。

Answer 10

我遇到了同样的问题，我重命名了“.m2”上的“repository”文件夹（类似于repositoryBkp，名称并不重要，以防万一出现问题）并创建一个新的“repository”文件夹，然后我重新运行maven和所有项目编译成功

Answer 11

In my case I had the same dependency listed twice in the same pom.xml. Make sure it's only used once.

Answer 12

对我来说，与我的dependencyManagement中的分类器相关的问题我有项目的依赖项（和“版本”关闭诅咒）我从dependencyManagement中删除了它解决了这个问题

Answer 13

If you are using modules and need lombok for child module you need to explicitly declare version as well like :

<dependencies>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.24</version>
            <optional>true</optional>
        </dependency>
    </dependencies>

It helped in my case.

Answer 14

In my case I was putting tomcat decency then I got the error and this what I used.

<dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-core</artifactId>
            <version>9.0.44</version>
        </dependency>

Answer 15

Most probably your spring-framework-bom might not be existing. Recheck for the version if it has ".RELEASE" at the end.