Grails问题在关联列表中列出重复的姓氏

我有一个框架式的Grails应用程序，它有两个域：Person和Course。人属于课程，课程有很多人。我已修改了课程的show.gsp，以列出与所选课程相关的所有人员

我遇到的问题是，显示给定课程中所有人员的列表不会显示数据库中姓氏重复的人员。例如，如果我有4个人：“John Doe”、“Jane Doe”、“Joe Doe”、“Edward Smith”，那么列表将只显示：

• 无名氏
• 爱德华·史密斯

然而，这4个人都在数据库中。此外，/person/list将显示所有姓名。因此，问题只在于与课程相关的人员列表。请参阅下面的相关代码。有什么想法吗

个人域：

class Person implements Comparable {

    static mapping = { sort lastName: "asc" }

    // Needed to sort association in Course domain (due to Grails bug)
    int compareTo(obj) {
        lastName.compareToIgnoreCase( obj.lastName );
    }

    String firstName
    String lastName
    String email

    Course course

    static belongsTo = [ course:Course ]

    static constraints = {
        firstName size: 1..50, blank: false
        lastName size: 1..50, blank: false
        email email: true
        course()
        firstName(unique: ['lastName', 'email'])
    }

    String toString() {
        return this.lastName + ", " + this.firstName;
    }
}

class Course {

    int maxAttendance
    SortedSet persons

    static hasMany = [ persons:Person ]

    static mapping = {
        persons cascade:"all-delete-orphan"
    }

    def getExpandablePersonList() {
        return LazyList.decorate(persons,FactoryUtils.instantiateFactory(Person.class))
    }

    static constraints = {
        maxAttendance size: 1..3, blank: false
    }
}

<g:if test="${courseInstance?.persons}">
                <br />
                <table>
                    <thead>
                        <tr>
                            <th>#</th>
                            <g:sortableColumn property="person"
                                title="${message(code: 'person.lastName.label', default: 'Person')}" />

                        </tr>
                    </thead>
                    <tbody>
                        <g:set var="counter" value="${1}" />
                        <g:each in="${courseInstance.persons}" status="i" var="p">
                            <tr class="${(i % 2) == 0 ? 'even' : 'odd'}">
                                <td>
                                    ${counter}
                                </td>
                                <td class="property-value" aria-labelledby="persons-label"><g:link
                                        controller="person" action="show" id="${p.id}">
                                        ${p?.encodeAsHTML()}</td>

                            </tr>
                            <g:set var="counter" value="${counter + 1}" />
                        </g:each>
                    </tbody>
                </table>
            </g:if>

课程域：

class Person implements Comparable {

    static mapping = { sort lastName: "asc" }

    // Needed to sort association in Course domain (due to Grails bug)
    int compareTo(obj) {
        lastName.compareToIgnoreCase( obj.lastName );
    }

    String firstName
    String lastName
    String email

    Course course

    static belongsTo = [ course:Course ]

    static constraints = {
        firstName size: 1..50, blank: false
        lastName size: 1..50, blank: false
        email email: true
        course()
        firstName(unique: ['lastName', 'email'])
    }

    String toString() {
        return this.lastName + ", " + this.firstName;
    }
}

class Course {

    int maxAttendance
    SortedSet persons

    static hasMany = [ persons:Person ]

    static mapping = {
        persons cascade:"all-delete-orphan"
    }

    def getExpandablePersonList() {
        return LazyList.decorate(persons,FactoryUtils.instantiateFactory(Person.class))
    }

    static constraints = {
        maxAttendance size: 1..3, blank: false
    }
}

<g:if test="${courseInstance?.persons}">
                <br />
                <table>
                    <thead>
                        <tr>
                            <th>#</th>
                            <g:sortableColumn property="person"
                                title="${message(code: 'person.lastName.label', default: 'Person')}" />

                        </tr>
                    </thead>
                    <tbody>
                        <g:set var="counter" value="${1}" />
                        <g:each in="${courseInstance.persons}" status="i" var="p">
                            <tr class="${(i % 2) == 0 ? 'even' : 'odd'}">
                                <td>
                                    ${counter}
                                </td>
                                <td class="property-value" aria-labelledby="persons-label"><g:link
                                        controller="person" action="show" id="${p.id}">
                                        ${p?.encodeAsHTML()}</td>

                            </tr>
                            <g:set var="counter" value="${counter + 1}" />
                        </g:each>
                    </tbody>
                </table>
            </g:if>

修改了show.gsp课程：

class Person implements Comparable {

    static mapping = { sort lastName: "asc" }

    // Needed to sort association in Course domain (due to Grails bug)
    int compareTo(obj) {
        lastName.compareToIgnoreCase( obj.lastName );
    }

    String firstName
    String lastName
    String email

    Course course

    static belongsTo = [ course:Course ]

    static constraints = {
        firstName size: 1..50, blank: false
        lastName size: 1..50, blank: false
        email email: true
        course()
        firstName(unique: ['lastName', 'email'])
    }

    String toString() {
        return this.lastName + ", " + this.firstName;
    }
}

class Course {

    int maxAttendance
    SortedSet persons

    static hasMany = [ persons:Person ]

    static mapping = {
        persons cascade:"all-delete-orphan"
    }

    def getExpandablePersonList() {
        return LazyList.decorate(persons,FactoryUtils.instantiateFactory(Person.class))
    }

    static constraints = {
        maxAttendance size: 1..3, blank: false
    }
}

<g:if test="${courseInstance?.persons}">
                <br />
                <table>
                    <thead>
                        <tr>
                            <th>#</th>
                            <g:sortableColumn property="person"
                                title="${message(code: 'person.lastName.label', default: 'Person')}" />

                        </tr>
                    </thead>
                    <tbody>
                        <g:set var="counter" value="${1}" />
                        <g:each in="${courseInstance.persons}" status="i" var="p">
                            <tr class="${(i % 2) == 0 ? 'even' : 'odd'}">
                                <td>
                                    ${counter}
                                </td>
                                <td class="property-value" aria-labelledby="persons-label"><g:link
                                        controller="person" action="show" id="${p.id}">
                                        ${p?.encodeAsHTML()}</td>

                            </tr>
                            <g:set var="counter" value="${counter + 1}" />
                        </g:each>
                    </tbody>
                </table>
            </g:if>

#
${counter}
${p？.encodeAsHTML（）}

您使用了一个分类数据集进行关联，Person的

比较将两个姓氏相同的人视为相同的人，因此第二个和后续的姓氏相同的人不会首先添加到集合中。
很好的捕获，谢谢。你认为最好的解决方法是什么？我遇到了许多问题，无法正确地对关联进行排序，因此我当前的实现@littleK说实话，我真的不知道。在我的应用程序中，我总是在排序无关紧要时使用普通集（如果我需要在gsp中以特定顺序显示结果，则使用代码排序），或者在排序无关紧要时使用列表。无论如何，谢谢。虽然我知道这对性能不利，但我只想在show.gsp中对列表进行排序。我想不出别的办法了！您可以将“compareTo”函数更改为首先检查姓氏，但如果响应为0（表示相等），则返回姓氏的比较。注意，这仍然是一件坏事。。。compareTo应该检查ID，因为如果两个人的名字相同，你会希望他们出现两次。您认为sort调用是正确的，您可以将其改为NamedQuery，以使其更加干燥