javascript - APEX:如何实现循环级联选择列表(多对多)
问题描述
在处理多对多关系时,如何为选择列表实现循环级联逻辑?
例如,我创建了一个简单的测试应用程序来跟踪书籍和作者。
(这比我的实际业务场景要简单得多,而且更清楚地显示了问题。)
主页包含:
- 提交页面的按钮
- 书籍选择列表
- 作者的选择列表
我正在使用提交按钮,因为我的真实业务场景包括一个非常长的报告,需要 20-60 秒才能刷新 - 并且在提交页面之前,用户需要从十几个选择列表中进行选择拉报告。
这是一个完整的脚本,其中包含我正在使用的所有测试数据:
CREATE table "BOOK" (
"ID" INTEGER GENERATED ALWAYS AS IDENTITY NOT NULL ENABLE,
"TITLE" VARCHAR2(100) NOT NULL ENABLE,
constraint "BOOK_CK" check ("TITLE"<>''),
constraint "BOOK_PK" primary key ("ID"),
constraint "BOOK_UK1" unique ("TITLE")
)
/
CREATE table "AUTHOR" (
"ID" INTEGER GENERATED ALWAYS AS IDENTITY NOT NULL ENABLE,
"NAME" VARCHAR2(100) NOT NULL ENABLE,
constraint "AUTHOR_CK" check ("NAME"<>''),
constraint "AUTHOR_PK" primary key ("ID"),
constraint "AUTHOR_UK1" unique ("NAME")
)
/
INSERT INTO BOOK (TITLE) VALUES ('BOOK01');
INSERT INTO BOOK (TITLE) VALUES ('BOOK02');
INSERT INTO BOOK (TITLE) VALUES ('BOOK03');
INSERT INTO BOOK (TITLE) VALUES ('BOOK04');
INSERT INTO BOOK (TITLE) VALUES ('BOOK05');
INSERT INTO BOOK (TITLE) VALUES ('BOOK06');
INSERT INTO BOOK (TITLE) VALUES ('BOOK07');
INSERT INTO BOOK (TITLE) VALUES ('BOOK08');
INSERT INTO BOOK (TITLE) VALUES ('BOOK09');
INSERT INTO BOOK (TITLE) VALUES ('BOOK10');
INSERT INTO BOOK (TITLE) VALUES ('BOOK11');
INSERT INTO BOOK (TITLE) VALUES ('BOOK12');
INSERT INTO BOOK (TITLE) VALUES ('BOOK13');
INSERT INTO BOOK (TITLE) VALUES ('BOOK14');
INSERT INTO BOOK (TITLE) VALUES ('BOOK15');
INSERT INTO BOOK (TITLE) VALUES ('BOOK16');
INSERT INTO BOOK (TITLE) VALUES ('BOOK17');
INSERT INTO BOOK (TITLE) VALUES ('BOOK18');
INSERT INTO BOOK (TITLE) VALUES ('BOOK19');
INSERT INTO BOOK (TITLE) VALUES ('BOOK20');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR01');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR02');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR03');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR04');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR05');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR06');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR07');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR08');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR09');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR10');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR11');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR12');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR13');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR14');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR15');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR16');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR17');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR18');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR19');
INSERT INTO AUTHOR (NAME) VALUES ('AUTHOR20');
CREATE table "BOOK_AUTHOR" (
"ID" INTEGER GENERATED ALWAYS AS IDENTITY NOT NULL ENABLE,
"BOOK_ID" INTEGER NOT NULL ENABLE,
"AUTHOR_ID" INTEGER NOT NULL ENABLE,
constraint "BOOK_AUTHOR_PK" primary key ("ID"),
constraint "BOOK_AUTHOR_UK1" unique ("BOOK_ID","AUTHOR_ID")
)
/
ALTER TABLE BOOK_AUTHOR ADD FOREIGN KEY (BOOK_ID)
REFERENCES BOOK (ID) ENABLE
/
ALTER TABLE BOOK_AUTHOR ADD FOREIGN KEY (AUTHOR_ID)
REFERENCES AUTHOR (ID) ENABLE
/
CREATE OR REPLACE VIEW "VW_BOOK_AUTHOR" AS
SELECT ba.ID,
ba.BOOK_ID,
b.TITLE BOOK_TITLE,
ba.AUTHOR_ID,
a.NAME AUTHOR_NAME
FROM BOOK_AUTHOR ba
LEFT JOIN BOOK b on b.ID = ba.BOOK_ID
LEFT JOIN AUTHOR a on a.ID = ba.AUTHOR_ID
/
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK01' AND a.NAME='AUTHOR01';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK02' AND a.NAME='AUTHOR02';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK03' AND a.NAME='AUTHOR03';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK04' AND a.NAME='AUTHOR04';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK05' AND a.NAME='AUTHOR05';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK06' AND a.NAME='AUTHOR06';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK07' AND a.NAME='AUTHOR07';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK08' AND a.NAME='AUTHOR08';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK09' AND a.NAME='AUTHOR09';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK10' AND a.NAME='AUTHOR10';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK11' AND a.NAME='AUTHOR11';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK12' AND a.NAME='AUTHOR12';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK13' AND a.NAME='AUTHOR13';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK14' AND a.NAME='AUTHOR14';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK15' AND a.NAME='AUTHOR15';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK16' AND a.NAME='AUTHOR16';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK17' AND a.NAME='AUTHOR17';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK18' AND a.NAME='AUTHOR18';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK19' AND a.NAME='AUTHOR19';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK20' AND a.NAME='AUTHOR20';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK02' AND a.NAME='AUTHOR01';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK02' AND a.NAME='AUTHOR03';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK04' AND a.NAME='AUTHOR03';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK04' AND a.NAME='AUTHOR05';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK06' AND a.NAME='AUTHOR05';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK06' AND a.NAME='AUTHOR07';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK08' AND a.NAME='AUTHOR07';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK08' AND a.NAME='AUTHOR09';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK10' AND a.NAME='AUTHOR09';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK10' AND a.NAME='AUTHOR11';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK12' AND a.NAME='AUTHOR11';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK12' AND a.NAME='AUTHOR13';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK14' AND a.NAME='AUTHOR13';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK14' AND a.NAME='AUTHOR15';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK16' AND a.NAME='AUTHOR15';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK16' AND a.NAME='AUTHOR17';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK18' AND a.NAME='AUTHOR17';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK18' AND a.NAME='AUTHOR19';
INSERT INTO BOOK_AUTHOR (BOOK_ID,AUTHOR_ID) SELECT b.ID, a.ID FROM BOOK b, AUTHOR a WHERE b.TITLE='BOOK20' AND a.NAME='AUTHOR19';
此时,如果您选择一本书,然后单击按钮提交页面,则作者列表将缩小到仅所选书籍的作者。(如果您选择作者,反之亦然。)
对于下一步,我需要在不提交和刷新整个页面的情况下刷新选择列表。
让我们首先将级联设置添加到其中一个选择列表 (P1_AUTHOR) :
到目前为止,一切都很好。
现在,当用户选择一本书时,作者选择列表会自动刷新。
但是,当我们还为其他选择列表配置级联设置时,我们会遇到问题:
现在,当我们运行页面并尝试选择一本书或作者时,页面崩溃并出现 Javascript 异常:
错误是Maximum call stack size exceeded
,表示无限循环执行(使用递归)。
这似乎可能是APEX代码中的错误/疏忽,因为技术状况很容易通过正确/稳健的逻辑解决。
也就是说,我该如何解决这个问题?
是否有不同的方式来配置级联选项以使其工作?
或者我可以编写自定义动态操作和 Javascript 来手动提交单个项目,并手动刷新选择列表?
解决方案
首先,我只想说,问个问题的方式!:)
正如您所发现的,“级联”部分是从父级流向子级,而不是循环流向(这可能导致堆栈溢出!抱歉,无法抗拒)。
我会给你一个解决方案,但我会预先承认它不是最理想的,因为选择列表的每次更改都需要两个 Ajax 调用,而不仅仅是一个。我会向 APEX 团队提出这个问题,希望他们能在未来解决这个问题。
我将假设人们已经运行了您的脚本并且有一个带有 HTML 区域的空白页面来开始这些步骤。我的页面是 53,所以人们需要相应地进行更改。
第 1 部分:基础知识
将页面项目添加到区域。将Name设置为P53_BOOK,将Type设置为Select List,将 List of Values Type设置为SQL Query。在SQL 查询字段中输入以下代码:
select title d, id r from book where ( :P53_AUTHOR is null or id in ( select book_id from book_author where author_id = :P53_AUTHOR ) ) order by title
将另一个项目添加到该区域。将Name设置为P53_AUTHOR,将Type设置为Select List,并将 List of Values Type设置为SQL Query。在SQL 查询字段中输入以下代码:
select name d, id r from author where ( :P53_BOOK is null or id in ( select author_id from book_author where book_id = :P53_BOOK ) ) order by name
在 Page Designer 的 Rendering 窗格中,右键单击P53_BOOK,选择Create Dynamic Action,然后将其Name设置为P53_BOOK changed。将客户端条件类型设置为JavaScript 表达式,并在JavaScript 表达式字段中输入以下代码:
this.browserEvent.originalEvent !== undefined
虽然看起来很奇怪,但这将阻止动态操作在其他项目刷新时触发(防止不同的循环逻辑问题;有关详细信息,请参阅此内容)。
在操作级别,将Action从Show更改为Execute PL/SQL Code。将PL/SQL 代码设置为
null;
并将要提交的项目设置为P53_BOOK。此操作仅用于在您接下来创建的刷新操作之前更新 P53_BOOK 的会话状态。- 添加在执行 PL/SQL 代码操作之后触发的新操作。将Action设置为Refresh,将Selection Type设置为Item(s),将Item(s)设置为P53_AUTHOR。
右键单击P53_AUTHOR,选择Create Dynamic Action,然后将其Name设置为P53_AUTHOR changed。将客户端条件类型设置为JavaScript 表达式,并在JavaScript 表达式字段中输入以下代码:
this.browserEvent.originalEvent !== undefined
在操作级别,将操作更改为执行 PL/SQL 代码。将PL/SQL 代码设置为
null;
并将要提交的项目设置为P53_AUTHOR。- 添加在执行 PL/SQL 代码操作之后触发的新操作。将Action设置为Refresh,将Selection Type设置为Item(s),将Item(s)设置为P53_BOOK。
如果你运行它,它应该会按预期工作(大部分情况下)。最大的问题是,如果您对一个项目进行更改并刷新另一个项目,则另一个项目中的选择将始终丢失 - 即使刷新后的项目中存在预刷新值。
以下步骤可用于自动重新选择可用的值。
第 2 部分:恢复先前选择的值(可选)
转到P53_BOOK 更改的动态操作。添加一个在前两个动作之前触发的新真实动作。将操作设置为执行 JavaScript 代码并在代码字段中输入以下代码:
$('#P53_BOOK').data('last-val', $v('P53_BOOK'));
该代码使用 jQuery 的
data
方法来存储项目预刷新的值。您将在刷新后稍后使用它。转到P53_AUTHOR 更改的动态操作。添加一个在前两个动作之前触发的新真实动作。将操作设置为执行 JavaScript 代码并在代码字段中输入以下代码:
$('#P53_AUTHOR').data('last-val', $v('P53_AUTHOR'));
右键单击P53_BOOK并选择创建动态操作。将Name设置为P53_BOOK refreshed并将Event设置为After Refresh。
在操作级别,将操作设置为执行 JavaScript 代码并在代码字段中输入以下内容:
$s('P53_BOOK', $('#P53_BOOK').data('last-val'), null, true);
该代码使用该方法设置 P53_BOOK 的值
data
(这次作为 getter)。$s
( )的最后一个参数true
被传递以抑制更改事件,否则会创建更多循环逻辑。- 右键单击P53_AUTHOR并选择Create Dynamic Action。将Name设置为P53_AUTHOR refreshed并将Event设置为After Refresh。
在操作级别,将操作设置为执行 JavaScript 代码并在代码字段中输入以下内容:
$s('P53_AUTHOR', $('#P53_AUTHOR').data('last-val'), null, true);
那应该这样做。但是还有一件更烦人的事情......如果您在任一字段中选择一个空值,您可能希望它刷新两个字段(显示两者的所有选项),但它不会那样工作。如果需要,我建议只添加一个单独的重置按钮。否则,您最好用原始 JavaScript 代码编写所有这些内容。
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