Is there any way to use dynamic keys with the node-mongodb-native driver? By this I mean having a variable hold the key instead of using the key directly.
As in when one would normally do this:
db.createCollection('col', function(err, col){
col.insert({'_id':'wak3ajakar00'});
}
to do this instead:
db.createCollection('col', function(err, col){
var ID = '_id';
col.insert({ID:'wak3ajakar00'});
}
When I run the latter code, I end up with a document in collection db.col with a key called ID
in addition to a standardly created _id
, as opposed to just a key _id
with the value wak3ajakar00
. This leads me to believe that it isn't actually possible to do this directly.
Instead, I'm now just creating the document that I want to insert ahead of time as follows:
db.createCollection('col', function(err, col){
var ID = 'wak3ajakar00';
var key = '_id';
insertion = {}
insertion[key] = ID;
col.insert(insertion);
}
This works exactly like I want it to, but I just wanted to know if there are any better ways to go about this. JavaScript, NodeJS, and MongoDB are all new to me, so I feel like I could easily be missing something. If not, are there any cleaner ways to write the above code in JavaScript?
Best, and thanks,
Sami
2020 Edit: Object literals can now be created in a couple of handy new ways:
You can now use a variable as a property name in an object literal by wrapping it in square brackets:
const ID = "_id";
col.insert({ [ID]: "wak3ajakar00" });
You can use the variable name as the property name, and the variable value as the property value in an object literal like this:
const _id = "wak3ajakar00";
col.insert({ _id });
Original Answer from 2011:
In object literal syntax, you cannot use a variable as the key name, only values. The way to do it, is the way you already discovered - create your object first, then add the property as a separate step using square bracket notation.
var obj = {};
var ID = "_id";
obj[ID] = "wak3ajakar00";
You can write a small function that creates such an object
var obj = function(key, value, obj) {
obj = obj || {};
obj[key] = value;
return obj;
}
// Usage
foo = obj('foo' + 'bar', 'baz');
// -> {'foobar': 'baz'}
foo = obj('stack' + 'over', 'flow', foo);
// -> {'foobar': 'baz', 'stackover': 'flow'}
Don't know if calling this function obj is a good idea.
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