[英]How do I add an empty array to an object array?
basically I have an array that I pull data from. 基本上我有一个数据,我从中提取数据。 I would like to add a new array to it so I can pull additional data.
我想为它添加一个新数组,以便我可以提取更多数据。
var myArray.libraries = []
gets items added via a for loop like this: 获取通过for循环添加的项目,如下所示:
for(var x=0; x < items.length; x++){
myArray.libraries ({ name: items(x).name, state: items(x).state});
}
that works great and I can get what I need from myArray.libraries .name
. 这很好用,我可以从
myArray.libraries .name
获得我需要的东西。 I need to add something like "books" so each entry can have it's list of books. 我需要添加类似“书籍”的内容,以便每个条目都可以拥有它的书籍列表。 There could be 1 or more books.
可能有一本或多本书。
to be clear I'm using angular so I use something like this to output for each library: 要清楚我正在使用角度,所以我使用这样的东西为每个库输出:
<div ng-repeat="library in libraries">
<p>{{library.name}}</p>
</div>
I just need to add books
so I can loop through each book in that library: 我只需要添加
books
这样我就可以遍历该库中的每本书:
<div ng-repeat="book in libraries.books">
<p>{{book.name}}</p>
</div>
I tried using myArray.libraries.books = []
but that didn't add the collect to each library. 我尝试使用
myArray.libraries.books = []
但没有将collect添加到每个库。 I also tried myArray.libraries.push({ books: { } })
but that didn't have any affect and gave me an error that I couldn't push to myArray.libraries.books
since books didn't exist. 我也尝试了
myArray.libraries.push({ books: { } })
但是这没有任何影响并且给了我一个错误,我无法推送到myArray.libraries.books
因为书籍不存在。
EDIT 编辑
Here's some sample code. 这是一些示例代码。 I'm using angular but the principle should be the same:
我使用角度,但原则应该是相同的:
$scope.libraries= [];
//start loop to get the installations
for (var x = 0; x < res.rows.length; x++) {
$scope.libraries.push({ ... , books: []});
//run a new query to get the additional libraries info
var booksQuery = query to get books;
//run query to get results and loop through them
for (var i = 0;i < res2.rows.length; i++) {
$scope.libraries[x].books.push({ name: res2.rows.item(i).prodName });
}
});
}
EDIT 编辑
I ran some tests and it turns out when I do my second database call it doesn't know the original $scope
exists. 我运行了一些测试,结果当我进行第二次数据库调用时,它不知道原始的
$scope
存在。
Try as follows: 尝试如下:
for(var x=0; x < items.length; x++){
myArray.libraries ({ name: items(x).name, state: items(x).state, books: []});
}
That should do the trick. 这应该够了吧。
Basically the problem is that you are trying to push array to an array. 基本上问题是你正在尝试将数组推送到数组。 You can push another array to your
libraries
, but to access books you have to use index to access specific item like myArray.libraries[0].books[0]
您可以将另一个数组推送到您的
libraries
,但要访问书籍,您必须使用索引来访问特定项目,如myArray.libraries[0].books[0]
So I assume you have to change myArray.libraries.push({ books: { } })
to myArray.libraries.push({ books: [] })
所以我假设您必须将
myArray.libraries.push({ books: { } })
更改为myArray.libraries.push({ books: [] })
I have created a plunker for you. 我为你创造了一个plunker。 Please refer to
请参阅
" http://plnkr.co/edit/0FKg2fbe4CY11Oz6aSBF?p=preview " “ http://plnkr.co/edit/0FKg2fbe4CY11Oz6aSBF?p=preview ”
$scope.libraries = {
books : [
{"name" : "book1"},
{"name" : "book2"},
{"name" : "book3"}
]
};
This will help you. 这会对你有所帮助。
DB calls are async, so the 2nd db call shouldn't be in loop. 数据库调用是异步的,因此第二个数据库调用不应该在循环中。 Please check if this works
请检查一下是否有效
$scope.libraries = [];
init();
function init() {
// do the first db transaction
}
// transaction1 callback
function trans1Callback(result) {
addBooks(result);
}
var i = 0;
function addBooks(result) {
// to stop iteration at the end of records
if (i >= result.rows.length) {
return;
}
var item = result.rows.item(i);
var data = {name: item.name, state: item.state, books: []};
// do the second db transaction
// transaction2 callback
function trans2Callback(result2) {
for (var j =0; j < result2.rows.length; j++) {
var book = result.rows.item(j);
data.books.push({ name: book.prodName });
}
// push to scope libraries
$scope.libraries.push(data);
// do increment
i++;
// Call addBooks again to process next record
addBooks(result);
}
}
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