I'm using MongoDB and the node-mongodb-native driver.
I'm trying to return all records with a distinct attribute.
This seems to work, however it only returns the value which I'm checking for being distinct, not all values in each document.
This is what I have tried to return just the name field, I've also tried without it and variations of, but it always only returns the item_id's in an array.
this.collection.distinct("item_id", [{"name" : true}, {sold : {"$exists" : true}}], function(err, results) {
if (err) {
callback(err);
} else {
console.log(results);
}
});
Any suggestions how to get all the data from each document?
Thank you!
EDIT: Using Map Reduce
So, I just setup the start of a map reduce, using the node-mongodb-native, here's what I have so far:
var map = function() {
emit(this._id, {"_id" : this._id, "name" : this.name});
}
var reduce = function(key, values) {
var items = [];
values.forEach(function(v) {
items.push(v);
});
return {"items" : items};
}
this.collection.mapReduce(map, reduce, {out: "res"}, function(err, results) {
if (err) {
console.log(err);
} else {
console.log(results);
}
});
I know the logic isn't in there for distinct, but the results is the db object, I can't use 'toArray' on it. Any ideas why this might be?
Related
I'm attempting to write a find query where one of the keys is unknown at the time the query is run, for example on the following document I'm interested in returning the document if "setup" is true:
{
"a": {
"randomstringhere": {
"setup": true
}
}
}
However I can't work how to wildcard the "randomstringhere" field as it changes for each document in the collection.
Can somebody help?
There is not much you can do with that. But you can modify your collection schema like
{
"a": [
{
"keyName": "randomstringhere",
"setup": true
},
//...
]
}
you can than write query to look
{
'a' : { $elemMatch: { setup: true } ,
}
You can't do this with a single query, as with the current design you would need a mechanism to get all the random keys that you need and then assemble the query document that uses the $or operator in the event that you get a list of variable key name.
The first part of your operation is possible using Map-Reduce. The following mapreduce operation will populate a separate collection called collectionKeys with all the random keys as the _id values:
mr = db.runCommand({
"mapreduce": "collection",
"map" : function() {
for (var key in this.a) { emit(key, null); }
},
"reduce" : function() { },
"out": "collectionKeys"
})
To get a list of all the random keys, run distinct on the resulting collection:
db[mr.result].distinct("_id")
Example Ouput
["randomstring_1", "randomstring_2", "randomstring_3", "randomstring_4", ...]
Now given the list above, you can assemble your query by creating an object that will have its properties set within a loop. Normally your query document will have this structure:
var query = {
"$or": [
{ "a.randomstring_1.setup": true },
{ "a.randomstring_2.setup": true },
{ "a.randomstring_3.setup": true }
]
};
which you can then use in your query:
db.collection.find(query)
So using the above list of subdocument keys, you can dynamically construct the above using JavaScript's map() method:
mr = db.runCommand({
"mapreduce": "collection", // your collection name
"map" : function() { // map function
for (var key in this.a) { emit(key, null); }
},
"reduce" : function() { }, // empty reducer that doesn't do anything
"out": "collectionKeys" // output collection with results
})
var randomstringKeysList = db[mr.result].distinct("_id"),
orOperator = randomstringKeysList.map(function (key){
var o = {};
o["a."+ key +".setup"] = true;
return o;
}),
query = { "$or": orOperator };
db.collection.find(query);
I'm trying to delete all folders on MongoDB whose descriptions contain a number higher than 10. Can you tell me how to do that?
I've been trying desperately since hours...
Thanks very much!
Robomongo
You need a mechanism to get a list of the keys in the collection first, filter the list for the ones that have a number greater than 10 and then generate a query that you will use with the $unset operator in your update. Your update document should have this structure:
var update = {
"$unset": {
"p11": "",
"p12": "",
...
}
}
which you will use in your update as
db.collection.update({}, update, {multi: true});
You need the mapReduce() command to generate that update document. The following mapreduce operation will populate a separate collection with the document as the value:
db.collection.mapReduce(
function() {
var map = this;
for (var key in map) {
if (map.hasOwnProperty(key)){
num = parseInt(key.replace(/[^\d.]/g, '' ));
if (num > 10) emit(null, key);
}
}
},
function(key, values) {
return values.reduce(function(o, v) {
o[v] = "";
return o;
}, {});
},
{ "out": "filtered_keys" }
);
You can then run a query on the resultant collection to get the update document and do the actual update:
var update = {
"$unset": db.filtered_keys.findOne({"_id": null}).value
},
options = { "multi": true };
db.collection.update({}, update, options);
I was looking to pull(remove) values from my data collection based on array index.
this is how my collection looks.
"experience" : [
"neeee",
"avvvvvvv",
],
I'm looking to remove experience[1]
var update = {
$pull: {
'profile.experience': delet
}
};
this.findByIdAndUpdate(id,update,{ 'new': true},function(err,doc) {
if (err) { console.log(err);
callback(err);
} else if(doc){
callback(null,doc);
}
my delet looks like this: [1]
i was not able to delete (pull) what may be the reason.
My document contains an array like:
{
"differentialDiagnosis" : "IART/Flutter",
"explanation" : "The rhythm.",
"fileName" : "A115a JPEG.jpg",
"history" : "1 year old with fussiness",
"interpretationList" : [
{
"interpretations" : [
ObjectId("54efe7c8d6d5ca3d5c580a22"),
ObjectId("54efe80bd6d5ca3d5c580a26")
]
},
{
"interpretations" : [
ObjectId("54efe80bd6d5ca3d5c580a26"),
ObjectId("54efe82ad6d5ca3d5c580a28")
]
}
],
}
and I want to remove all occurrences of ObjectId("54efe80bd6d5ca3d5c580a26"),
but I write a query:
db.ekgs.update({'interpretationList.interpretations':ObjectId("54c09fb3581c4c8c218d1a40")}, {$pull:{ 'interpretationList.$.interpretations':{ ObjectId("54c09fb3581c4c8c218d1a40")}})
This removes only first occurrence of ObjectId("54efe80bd6d5ca3d5c580a26").
The reason your query is only removing the first occurrence is because, as explained in this page in the documentation, "the positional $ operator acts as a placeholder for the first element that matches the query document".
The problem is that it is really tricky to deal with these types of updates with schema having embedded arrays in embedded objects in embedded arrays. In order to get around this problem, if you are able to flatten the schema, then your update becomes much easier. So if instead, your document looked like this:
{
"differentialDiagnosis" : "IART/Flutter",
"explanation" : "The rhythm.",
"fileName" : "A115a JPEG.jpg",
"history" : "1 year old with fussiness",
"interpretations" : [
ObjectId("54efe7c8d6d5ca3d5c580a22"),
ObjectId("54efe80bd6d5ca3d5c580a26"),
ObjectId("54efe82ad6d5ca3d5c580a28")
]
}
Then your query would be as simple as the one below. (Remember to add { "multi": true } as an option if you want to update multiple documents).
db.ekgs.update(
{ "interpretations": ObjectId("54efe80bd6d5ca3d5c580a26")},
{ "$pull": { "interpretations": ObjectId("54efe80bd6d5ca3d5c580a26") }}
);
But I understand that you might not be able to change the schema. In that case, you can try a solution that requires a small script. In the mongo shell, you can use the following bit of JavaScript to do the operation.
// Get cursor with documents requiring updating.
var oid = ObjectId("54efe80bd6d5ca3d5c580a26");
var c = db.ekgs.find({ "interpretationList.interpretations": oid });
// Iterate through cursor, removing oid from each subdocument in interpretationList.
while (c.hasNext()) {
var isModified = false;
var doc = c.next();
var il = doc.interpretationList;
for (var i in il) {
var j = il[i].interpretations.length;
while (j--) {
// If oid to remove is present, remove it from array
// and set flag that the document has been modified.
if (il[i].interpretations[j].str === oid.str) {
il[i].interpretations.splice(j, 1);
isModified = true;
}
}
}
// If modified, update interpretationList for document.
if (isModified) {
db.ekgs.update({ "_id": doc._id }, { "$set": { "interpretationList": il }});
}
}
UPDATE: Example of how it might work using the Node.js driver.
// Get cursor with documents requiring updating.
var oid = new ObjectID("54efe80bd6d5ca3d5c580a26");
var ekgs = db.collection("ekgs");
ekgs.find({ "interpretationList.interpretations": oid },
function(err, c) {
if(err) throw err;
// Iterate through cursor, removing oid from each subdocument in interpretationList.
c.each(function(err, doc) {
if (err) throw err;
// If doc is null then the cursor is exhausted/empty and closed.
if (doc != null) {
var isModified = false;
var il = doc.interpretationList;
for (var i in il) {
var j = il[i].interpretations.length;
while (j--) {
// If oid to remove is present, remove it from array
// and set flag that the document has been modified.
if (il[i].interpretations[j].equals(oid)) {
il[i].interpretations.splice(j, 1);
isModified = true;
}
}
}
// If modified, update interpretationList for document.
if (isModified) {
ekgs.update({ "_id": doc._id },
{ "$set": { "interpretationList": il }},
function(err, res) {
if (err) throw err;
// Callback.
console.log(res);
});
}
}
});
});
I'm coding a mongoose schema so I need a list of possible field in my collection.
Please how can I display all fields names in a specific collection, thank you.
switch to the db you're using and type:
mr = db.runCommand({
"mapreduce" : "myCollectionName",
"map" : function() {
for (var key in this) { emit(key, null); }
},
"reduce" : function(key, stuff) { return null; },
"out": "myCollectionName" + "_keys"
})
once you get result, type:
db[mr.result].distinct("_id")
and you will get a list of fields names.