I'm trying to do a 'findOne' operation in a model that has an array property and filter the results to only list the item if the string im searching is in that array.
Example:
var AppUser = server.loopback.getModel('AppUser');
AppUser.create({
"name":"juan"
"favoriteLetters":["a","b","c"]
},function(){
AppUser.findOne({where:{favoriteLetters:'a'}},function(error,appUser){
console.log(error,appUser);
});
});
So in this case i want to find a 'appUser' that has a favorite letter 'a'.
Thanks.
As far as I understood, possibility of such kind of a query depends on the underlying datasource and is not supported yet for relational DBs. But should be fine with memory storage or mongodb. More details and syntax for query is here: https://groups.google.com/d/msg/loopbackjs/8c8kw8EMiPU/yev3lsmrTFUJ
For anyone else who lands here, that query in your model is correct (for Mongo anyways).
{where:{favoriteLetters:'a'}
Reference:
Find document with array that contains a specific value
Related
Im not able to fetch the field value i need only the value of the particular field in node js query, but coming undefined
I need the nodejs query of this mongodb query
Try using projection into find query to return only values you want.
Also don't forget to use await or get the field name into then. And, of course, the query should return any document to get the field.
Check this example which would be similar in Node:
const value = await db.collectionsname.findOne({mobilenumber: mobilenumber},{_id: 0, field: 1}).fieldname
Projection stage is not mandatory but if you only want that value is a good practice not get all document from the DB.
sorry for the noob question.
I'm trying to write the CRUD endpoints for a Friendship model, which holds two users' IDs.
To create a Friendship the first thing I want to do is check if there is already an instance of that model, which would hold both IDs in any given order, so I wrote:
Friendship.findOne.all({users: [user1.id, user2.id]})
.then(.....
But the server responds with a 500 error: Friendship.findOne.all is not a function
What would be the proper way to do this?
I am assuming that you want to check if both id records/documents are present in your collection or not so for that you use $in operator like this
Friendship.find({id: {$in : [user1.id, user2.id]} })
.then(.....
This will return an array of records if any of id records will be present. And it will return empty array if non of the id records will present in your db
I have a question regarding compound index creation in mongodb:
Say I want to create this compound index:
cSchema.index({account:1, authorization: 1, c_type: 1});
Problem is, javascript doesn't guarantee dictionary order, so I won't be sure the compound index is in the order I want.
How can I make sure it's indeed {account:1, authorization:1, c_type:1} in that order ?
Thanks !
The simple answer is that most abuse the behaviour that simple String properties that don't parse to an integer on an Object will enumerate in creation order. Although not guaranteed in ES2015 for some enumeration methods, it does work in a confined environment like Node/V8. This has worked in most JS engines for a while now but had never been part of the ES spec before ES2015.
MongoDB
The underlying MongoDB driver createIndex function supports String, Array and Object index definitions. The parsing code is in a util function called parseIndexOptions.
If you specify an array of Strings, Array pairs, or Objects then the order will be fixed:
['location','type']
[['location', '2d'],['type', 1]]
[{location: '2d'},{type: 1}]
Also note that the createIndex code does use Object.keys to enumerate when it gets an Object of index properties.
Mongoose
The Schema#index function is documented as requiring an Object to pass to "MongoDB driver's createIndex() function" so looks to support passing through whatever options you provide.
There are a couple of places where indexes are further processed though. For example when you create a sub document with an index, the index needs to have the parent schema prefixed onto field names. On a quick glance I think this code still works with an Array but I can't see any tests for that in the Mongoose code so you might want to confirm it yourself.
Mongoose does have a compound index test that relies on Object property order.
I come from MySQL world so mongo queries are a bit difficult to make considering I can't really make sense of mongo style queries. I am trying to make a query for finding a string. The problem is from my very primitive knowledge about mongodb queries, the query I made isn't working. I tried it in mongoose as well in mongo shell.
Schema:
mongoose.Schema({
doctorID : String,
patientIDList : Array // array of strings
});
Query Objective:
I want to find a doctor with doctorID and then look inside the patientIDList for an ID xxx. If the patientIDList doesn't contains xxx then add xxx in the list otherwise just add nothing.
Query:
The 2 queries I tried
MyModel.findOne({'doctorID':newAppointment.doctorID}, {'patientIDList' : newAppointment.patientID}, function(err){...});
MyModel.findOne({'doctorID': newAppointment.doctorID, 'patientIDList': newAppointment.patientID}, function(err){...});
What am I doing wrong? How can I make a query?
It's always a bit of challenge to switch from a SQL to NoSQL DB and other way around. What you are trying to do is check if a value exists in an array. If the array is a string array you can simply query for the value in array.
MyModel.findOne({doctorID : newAppointment.doctorID}, {patientIDList :newAppointment.doctorID}, function(err, res){
console.log(err, res);
})
Further read: https://docs.mongodb.com/manual/tutorial/query-documents/#match-an-array-element
Relevant Question: Find document with array that contains a specific value
I have been exclusively using cypher queries of this client for Neo4j because there is no out of the box way of doing many things. One of those id to get nodes. There is no way to retrieve them without knowing their id, which is very low level. Any idea on how to run a
$client->findOne('property','value');
?
It should be straightforward but it isn't from the documentation.
Make Indexes on the properties you want to search, from a newly created $personNode
$personIndex = new \Everyman\Neo4j\NodeIndex($client, 'person');
$personIndex->add($personNode, 'name', $personNode->name);
Then later to search, the new PHP object $personIndex will reference the same, populated index as above.
$personIndex = new \Everyman\Neo4j\NodeIndex($client, 'person');
$match = $personIndex->findOne('name', 'edoceo');