Iterate: Difference between revisions
From NoSQLZoo
mNo edit summary |
mNo edit summary |
||
| Line 3: | Line 3: | ||
<div class="q nonum" data-lang="mongo"> | <div class="q nonum" data-lang="mongo"> | ||
<p class="strong">Iterating countries in South America stored in the 'world' collection.</p> | <p class="strong">Iterating countries in South America stored in the 'world' collection.</p> | ||
<pre class=def> | <pre class="def nonum"><nowiki> | ||
let cursor = db.world.find({continent:"South America"}) | let cursor = db.world.find({continent: "South America"}); | ||
while (cursor.hasNext()) { | while (cursor.hasNext()) { | ||
printjson(cursor.next()); | printjson(cursor.next()); | ||
} | }</nowiki></pre> | ||
</pre> | |||
</div> | </div> | ||
Revision as of 16:33, 18 July 2018
MongoDB's find() method returns a cursor object which can be iterated using while, hasNext() and next, or by using forEach().
Iterating countries in South America stored in the 'world' collection.
let cursor = db.world.find({continent: "South America"});
while (cursor.hasNext()) {
printjson(cursor.next());
}
let cursor = db.world.find({continent:"South America"})
cursor.forEach(printjson);
Cursors can also be converted to other JavaScript collection types, such as arrays.
In the following example an array is used to find the nth record in a result as an alternative to .find().skip(n).limit(1)
Find the 3rd result of the previous example.
db.world.find({continent:"South America"}).toArray()[3]