I have a search field within my application that I want users to enter a search term into and it searches across various fields in each Mongo document. Naturally, I can search data within the fields that are of type String (currently using a regular expression), but how do I do this for those with type Date or type Int that?
Note: when I say search within the field, I mean if a user types '16' into the search field, it will return dates that contain '16', e.g. 01/01/2016 or 16/03/2014. Same principle for integers.
One quick way I think is you can use $where
value to search val = "16"
db.foo.find({$where : "function(){ if(this.dateField.toString().indexOf(val)>= 0 || (""+this.intField).indexOf(val)>=0){return true;}}"})
What basically you can try is convert the field value into string and then search it in there. Downside is $where doesn't uses index, it basically scans the collection, You cannot use other operators when you are using $where.
Yes it is possible.
You can tell your find() to look into only fields which are of specific data types.
$type comes handy.
check out the following link for examples and usage.
https://docs.mongodb.com/manual/reference/operator/query/type/
an example would be
db.addressBook.find({"field": "search-value"}, { "field" : { $type : "double" } } )
will return documents where search-value has a match as well as if the field is of type double.
since i have an image hence posting it as another answer rather than a comment.
now if you notice, documents with ID 2 and ID 6 are exactly the same. Only difference is the data type for the zipcode field.
i ran my query with $and as you can see and it bring backs only the matching record. if i get rid of the $and and the $type condition it will bring back both the records.
i hope this will help you solve your issue.
I am trying to search based on multiple conditions which works but the problem is that does not behave like this.
Assuming i have a search query like
Orders.find({$or: {"status":{"$in":["open", "closed"]},"paymentStatus":{"$in":["unpaid"]}}}
)
and i add another filter parameter like approvalStatus it does not leave the previously found items but rather it treats the query like an AND that will return an empty collection of items if one of the queries does not match.
How can i write a query that regardless of what is passed into it, it will retain previously found items even if there is no record in one of the conditions.
like a simple OR query in sql
I hope i explained this well enough
Using $or here is the right approach, but its value needs to be an array of query expressions, not an object.
So your query should look something like this instead:
Orders.find({$or: [
{"status": {"$in": ["open", "closed"]}},
{"paymentStatus": {"$in": ["unpaid"]}},
{"approvalStatus": {"$in": ["approved"]}}
]})
I have an use case in which I want to compare each record of two collections in mongodb and after comparing each record I need to find mismatch fields of all record.
Let us take an example, in collection1 I have one record as {id : 1, name : "bks"}
and in collection2 I have a record as {id : 1, name : "abc"}
When I compare above two records with same key, then field name is a mismatch field as name is different.
I am thinking to achieve this use case using mapreduce in mongodb. But I am facing some problems while accessing collection name in map function. When I tried to compare it in map function, I got error as : "errmsg" : "exception: ReferenceError: db is not defined near '
Can anyone give me some thoughts on how to compare records using mapreduce?
I might have helped you to read the documentation:
When upgrading to MongoDB 2.4, you will need to refactor your code if your map-reduce operations, group commands, or $where operator expressions include any global shell functions or properties that are no longer available, such as db.
So from your error fragment, you appear to be referencing db in order to access another collection. You cannot do that.
If indeed you are intending to "compare" items in one collection to those in another, then there is no other approach other than looping code:
db.collection.find().forEach(function(doc) {
var another = db.anothercollection.findOne({ "_id": doc._id });
// Code to compare
})
There is simply no concept of "joins" as such available to MongoDB, and operations such as mapReduce or aggregate or others strictly work with one collection only.
The exception is db.eval(), but as per all of strict warnings in the documentation, this is almost always a very bad idea.
Live with your comparison in looping code.
What is the status of text search with haskell mongodb driver?
There is now 'LIKE' operator in mongo similar to SQL variants, so what is the best way to search a collection or the whole db for a particular text string?
I've read some people referencing external tools but I can also see that some text search was implemented in 2.4 mongo version which is done through command interface.
There should not be any problems doing it from console but how would I do it from haskell driver? I found 'runCommand' function in the driver APIs and it looks like it should be possible to send 'text' command to the server but the signature shows that it returns only one document - not a list of documents. So how is it done correctly?
How would I efficiently search for a word or a sentence in a collection or db so that it returns a list of documents containing the word? Is it possible to do without external tools using mongo 'text search' feature? SHould it be done in the application level?
Thanks.
The result type already contains the list of documents (that contain the searched text). Unfortunately, I could not test the query on my running database, but I have used runCommand to run an aggregation (before it was implemented for the haskell driver). The result document you get for such an query looks something like this:
{ results: [
{ score : ...,
obj : { ... }
},
...
],
... ,
ok : 1
}
The result document has a field results and its value is a document with fields score and obj. So in the end, you can find each of the matched document behind the obj-field in the list of results.
For more details, you should take a look here.
So this is Day 3 of learning Mongo Db. I'm coming from the MySql universe...
A lot of times when I need to write a query for a MySql table I'm unfamiliar with, I would use the "desc" command - basically telling me what fields I should include in my query.
How would I do that for a Mongo db? I know, I know...I'm searching for a schema in a schema-less database. =) But how else would users know what fields to use in their queries?
Am I going at this the wrong way? Obviously I'm trying to use a MySql way of doing things in a Mongo db. What's the Mongo way?
Type the below query in editor / mongoshell
var col_list= db.emp.findOne();
for (var col in col_list) { print (col) ; }
output will give you name of columns in collection :
_id
name
salary
There is no good answer here. Because there is no schema, you can't 'describe' the collection. In many (most?) MongoDb applications, however, the schema is defined by the structure of the object hierarchy used in the writing application (java or c# or whatever), so you may be able to reflect over the object library to get that information. Otherwise there is a bit of trial and error.
This is my day 30 or something like that of playing around with MongoDB. Unfortunately, we have switched back to MySQL after working with MongoDB because of my company's current infrastructure issues. But having implemented the same model on both MongoDB and MySQL, I can clearly see the difference now.
Of course, there is a schema involved when dealing with schema-less databases like MongoDB, but the schema is dictated by the application, not the database. The database will shove in whatever it is given. As long as you know that admins are not secretly logging into Mongo and making changes, and all access to the database is controller through some wrapper, the only place you should look at for the schema is your model classes. For instance, in our Rails application, these are two of the models we have in Mongo,
class Consumer
include MongoMapper::Document
key :name, String
key :phone_number, String
one :address
end
class Address
include MongoMapper::EmbeddedDocument
key :street, String
key :city, String
key :state, String
key :zip, String
key :state, String
key :country, String
end
Now after switching to MySQL, our classes look like this,
class Consumer < ActiveRecord::Base
has_one :address
end
class Address < ActiveRecord::Base
belongs_to :consumer
end
Don't get fooled by the brevity of the classes. In the latter version with MySQL, the fields are being pulled from the database directly. In the former example, the fields are right there in front of our eyes.
With MongoDB, if we had to change a particular model, we simply add, remove, or modify the fields in the class itself and it works right off the bat. We don't have to worry about keeping the database tables/columns in-sync with the class structure. So if you're looking for the schema in MongoDB, look towards your application for answers and not the database.
Essentially I am saying the exactly same thing as #Chris Shain :)
While factually correct, you're all making this too complex. I think the OP just wants to know what his/her data looks like. If that's the case, you can just
db.collectionName.findOne()
This will show one document (aka. record) in the database in a pretty format.
I had this need too, Cavachon. So I created an open source tool called Variety which does exactly this: link
Hopefully you'll find it to be useful. Let me know if you have questions, or any issues using it.
Good luck!
AFAIK, there isn't a way and it is logical for it to be so.
MongoDB being schema-less allows a single collection to have a documents with different fields. So there can't really be a description of a collection, like the description of a table in the relational databases.
Though this is the case, most applications do maintain a schema for their collections and as said by Chris this is enforced by your application.
As such you wouldn't have to worry about first fetching the available keys to make a query. You can just ask MongoDB for any set of keys (i.e the projection part of the query) or query on any set of keys. In both cases if the keys specified exist on a document they are used, otherwise they aren't. You will not get any error.
For instance (On the mongo shell) :
If this is a sample document in your people collection and all documents follow the same schema:
{
name : "My Name"
place : "My Place"
city : "My City"
}
The following are perfectly valid queries :
These two will return the above document :
db.people.find({name : "My Name"})
db.people.find({name : "My Name"}, {name : 1, place :1})
This will not return anything, but will not raise an error either :
db.people.find({first_name : "My Name"})
This will match the above document, but you will have only the default "_id" property on the returned document.
db.people.find({name : "My Name"}, {first_name : 1, location :1})
print('\n--->', Object.getOwnPropertyNames(db.users.findOne())
.toString()
.replace(/,/g, '\n---> ') + '\n');
---> _id
---> firstName
---> lastName
---> email
---> password
---> terms
---> confirmed
---> userAgent
---> createdAt
This is an incomplete solution because it doesn't give you the exact types, but useful for a quick view.
const doc = db.collectionName.findOne();
for (x in doc) {
print(`${x}: ${typeof doc[x]}`)
};
If you're OK with running a Map / Reduce, you can gather all of the possible document fields.
Start with this post.
The only problem here is that you're running a Map / Reduce on which can be resource intensive. Instead, as others have suggested, you'll want to look at the code that writes the actual data.
Just because the database doesn't have a schema doesn't mean that there is no schema. Generally speaking the schema information will be in the code.
I wrote a small mongo shell script that may help you.
https://gist.github.com/hkasera/9386709
Let me know if it helps.
You can use a UI tool mongo compass for mongoDb. This shows all the fields in that collection and also shows the variation of data in it.
If you are using NodeJS and want to get the all the field names using the API request, this code works for me-
let arrayResult = [];
db.findOne().exec(function (err, docs)){
if(err)
//show error
const JSONobj = JSON.parse(JSON.stringify(docs));
for(let key in JSONobj) {
arrayResult.push(key);
}
return callback(null, arrayResult);
}
The arrayResult will give you entire field/ column names
Output-
[
"_id",
"emp_id",
"emp_type",
"emp_status",
"emp_payment"
]
Hope this works for you!
Consider you have collection called people and you want to find the fields and it's data-types. you can use below query
function printSchema(obj) {
for (var key in obj) {
print( key, typeof obj[key]) ;
}
};
var obj = db.people.findOne();
printSchema(obj)
The result of this query will be like below,
you can use Object.keys like in JavaScript
Object.keys(db.movies.findOne())