grails - 不确定用于Groovy调用的输入参数:模糊方法重载

Question

我仍然对groovy / grails还是陌生的，但是当我尝试为Grails 3.0.9调用邮件插件时，无法确定以下语法有什么问题:

class Email {
    String subject;
    List<String> toEmail;
    List<String> ccEmail;
    List<String> bccEmail;
    String body;
}


    Email email = new Email(toEmail: ["test@mail.com"], body: "Hi", subject: "Yo")
    mailService.sendMail {
        to email.toEmail.toArray()
        from "no-reply@fake.com"
        cc email.ccEmail?.toArray()
        bcc email.bccEmail?.toArray()
        subject email.subject
        body email.body
    }

当我没有人要抄送时，cc参数行将引发以下异常。但是，我会以为Elvis运算符会返回null，一切都会很好。我想念什么？我觉得如果没有数据，也许我根本不应该设置cc和bcc字段，但是我不确定为什么会导致问题(也许是插件内部的问题)以及如何对此进行编码边缘情况(分别构建参数并将其作为变量传递？)

groovy.lang.GroovyRuntimeException: Ambiguous method overloading for method org.springframework.util.Assert#notEmpty.
Cannot resolve which method to invoke for [null, class java.lang.String] due to overlapping prototypes between:
    [interface java.util.Collection, class java.lang.String]
    [interface java.util.Map, class java.lang.String]
    at groovy.lang.MetaClassImpl.chooseMostSpecificParams(MetaClassImpl.java:3241) ~[groovy-2.4.5.jar:2.4.5]
    at groovy.lang.MetaClassImpl.chooseMethodInternal(MetaClassImpl.java:3194) ~[groovy-2.4.5.jar:2.4.5]
    at groovy.lang.MetaClassImpl.chooseMethod(MetaClassImpl.java:3137) ~[groovy-2.4.5.jar:2.4.5]
    at groovy.lang.MetaClassImpl.pickStaticMethod(MetaClassImpl.java:1508) ~[groovy-2.4.5.jar:2.4.5]
    at groovy.lang.MetaClassImpl.retrieveStaticMethod(MetaClassImpl.java:1404) ~[groovy-2.4.5.jar:2.4.5]
    at groovy.lang.MetaClassImpl.createStaticSite(MetaClassImpl.java:3383) ~[groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.createCallStaticSite(CallSiteArray.java:77) [groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.createCallSite(CallSiteArray.java:162) [groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48) [groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113) [groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:133) [groovy-2.4.5.jar:2.4.5]
    at grails.plugins.mail.MailMessageBuilder.cc(MailMessageBuilder.groovy:214) ~[mail-2.0.0.RC4.jar:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_51]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_51]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_51]
    at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_51]
    at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93) ~[groovy-2.4.5.jar:2.4.5]
    at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325) ~[groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:384) ~[groovy-2.4.5.jar:2.4.5]
    at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1019) ~[groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:69) ~[groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:52) [groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:154) [groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:166) [groovy-2.4.5.jar:2.4.5]
    at com.doctorsorders.email.EmailService$_sendEmail_closure1.doCall(EmailService.groovy:19) ~[main/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_51]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_51]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_51]
    at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_51]
    at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93) ~[groovy-2.4.5.jar:2.4.5]
    at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325) ~[groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:294) ~[groovy-2.4.5.jar:2.4.5]
    at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1019) ~[groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:42) ~[groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48) [groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113) [groovy-2.4.5.jar:2.4.5]
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125) [groovy-2.4.5.jar:2.4.5]

Answer 1

初始化您的 list

class Email {
    String subject
    List<String> toEmail = []
    List<String> ccEmail = []
    List<String> bccEmail = []
    String body
}