I need to search the items by their names via spring boot on a db implemented by mongodb. For a normal SQL database I would've done as follows:
#Query("SELECT * FROM customer WHERE UPPER(name) LIKE UPPER(CONCAT('%', :name, '%'))")
List<Customer> findByName(#Param("name") String name);
Yet it does not accept a normal 'SELECT' query, because it is a NoSQL database. Thus I need to query this collection by using JSON format, yet I have no idea of the implementation on spring-boot.. This is my first time using mongodb too.
Going through the posts on stackoverflow, I have found an example such as:
#Query("{'name':?0}")
And on this site there are examples. Also here there is an explanation of the query above. Yet still I have no idea how to convert the former query I have pasted above into a "json based query".
Note: I am extending MongoRepository on my repository.
Note2: The above query is case sensitive, that's the reason I am trying to query in upper case along with converting the column data into upper case.
UPDATE
#Query(" { $text: { $search: ?0 , $caseSensitive: false } }")
works perfectly(I had to index my collection by launching this command:db.customerCollection.createIndex({name: "text"}) ) to ignore case sensitivity, but I still need to implement 'LIKE'; because when I search 'user', it is able to find 'UsEr' etc. But if I search 'se', it doesn't bring me any result. Any help will be appreciated!
Thank you for your time!
I have resolved my issue by using $regex and writing the query as:
#Query(" { companyName: { $regex : '(?i)?0'} } }")
I would've never guessed to spend that much time for such a simple thing. But I am glad that it is resolved anyway !
[ref]
I have a question on best practises or ideal way how I should store the data in the database. As an example I have a Site that has a Country assigned.
Table Countries: id|name|alpha2
Table Sites: id|countryId|name
Each Site has a reference to the country ID.
I would like to create a new website using Meteor and its mongodb and was wondering how I should store the objects. Do I create a colleciton "countries" and "sites" and use the country _id to as a reference? Then resolve the references using transform?
Looking at SimpleSchema I came up with the following:
Schemas.Country = new SimpleSchema ({
name: {
type: String
},
alpha2: {
type: String,
max: 2
}
});
Schemas.Site = new SimpleSchema({
name: {
type: String,
label: "Site Name"
},
country: {
type: Schemas.Country
}
});
Countries = new Meteor.Collection("countries");
Countries.attachSchema(Schemas.Country);
Sites = new Meteor.Collection("sites");
Sites.attachSchema(Schemas.Site);
I was just wondering how this is then stored in the db. As I have 2 collections but inside the sites collection I do have defined country objects as well. What if a country changes its alpha2 code (very unlikely)?
Also this would continue where I have a collection called "conditions". Each condition will have a Site defined. I could now define the whole Site object into the condition object. What if the Sitename changes? Would I need to manually change it in all condition objects?
This confuses me a bit. I am very thankful for all your thoughts.
The challenge with Meteor is that its tightly bound to Mongo, which is not good to built OLTP app that require normalized DB design. Mongo is good for OLAP kind of apps which fall in WORM (Write Once Read Many) category. I would like to see Meteor supporting OrientDB as they do Mongo.
There can be two approaches:
Normalize the DB as we do in RDBMS and then retrieve data by hitting
data multiple times. Here is a good article explaining this approach - reactive joins in meteor.
Joins in
Meteor
are suggested in future. You can also try Meteor packages - publish
composite or
publish with
relations
Keep data de-normalized at least partially (for 1-N relation you can
embed things in document, for N-N relation you may having separate
collection). For instance, 'Student' can be embedded in 'Class' as
student will never be in more than 1 class, but to relate 'Student'
and 'Subject', they can be in different collections (N-N relation -
student will have more than one subject and each subject will be
taken by more than one student). For fetching N-N relation again you
can use the same approach that is mentioned point above.
I am not able to give you exact code example, but I hope it helps.
I've the following model in my SailsJS application, I want to add composite unique key on the fields 'room_name' and 'school_id'.
What I currently do is run this command from mongo:
db.room.ensureIndex({'room_name': 1, 'school_id':1}, {unique: true})
Question 1
Am I doing it right?
Question 2
Is it possible to modify my model so it automatically invokes this command without manually modifying the mongodb (from mongo command line)?
This is the model
module.exports = {
schema: true,
attributes: {
room_name: {
type: 'string',
required: true
},
school_id: {
type: 'string',
required: true
},
children_count: {
type: 'integer',
required: true
}
}
}
I created a sails hook to give advanced indexing options for models that use the sails-mongo adapter.
Supports all mongo indexing options.
https://www.npmjs.com/package/sails-hook-mongoat
Sails does not currently (as of v0.10) support multi-key indexes, although it is on our radar. For the time being, the way you are doing it--by specifying the index directly in the Mongo console--is the correct (and only) way.
Captain's log, stardate -303842.4081367327 (27th February 2019). Our destination is framework Sails 1.0x.
Even if Sails 1.0x/Waterline supports MongoDB composite indexes declaration in models (I'm not sure about that), when deploying your application in production, the indexes WILL NOT BE CREATED automatically... sad but true :(
Having that in mind...
Question 1 - Am I doing it right?
Yes you are... indexes are a bit complex and sometimes you will need to change them in production environment, so doing it by hand is necessary sometimes.
Question 2 - Creating indexes automatically
Yah... doing things by hand that could be done automagically is a pain in the donnuts...
For this issue, you can use the config/bootstrap.js file. Instead of ensureIndex function (it has been deprecated), you can use createIndex function (ensureIndex was an alias to createIndex).
A working example of how to AUTOMATICALLY do that can be found here.
I am using migrations https://github.com/tj/node-migrate
for generating indexes
my code example
in SQL world I could do something to the effect of:
SELECT name FROM table WHERE UPPER(name) = UPPER('Smith');
and this would match a search for "Smith", "SMITH", "SmiTH", etc... because it forces the query and the value to be the same case.
However, MongoDB doesn't seem to have this capability without using a RegEx, which won't use indexes and would be slow for a large amount of data.
Is there a way to convert a stored value to a particular case before doing a search against it in MongoDB?
I've come across the $toUpper aggregate, but I can't figure out how that would be used in this particular case.
If there's not way to convert stored values before searching, is it possible to have MongoDB convert a value when it's created in Mongo? So when I add a document to the collection it would force the "name" attribute to a particular case? Something like a callback in the Rails world.
It looks like there's the ability to create stored JS for MongoDB as well, similar to a Stored Procedure. Would that be a feasible solution as well?
Mostly looking for a push in the right direction; I can figure out the particular code once I know what I'm looking for, but so far I'm not even sure if my desired functionality is doable.
You have to normalize your data before storing them. There is no support for performing normalization as part of a query at runtime.
The simplest thing to do is probably to save both a case-normalized (i.e. all-uppercase) and display version of the field you want to search by. Suppose you are storing users and want to do a case-insensitive search on last name. You might store:
{
_id: ObjectId(...),
first_name: "Dan",
last_name: "Crosta",
last_name_upper: "CROSTA"
}
You can then create an index on last_name_upper, and query like:
> db.users.find({last_name_upper: "CROSTA"})
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())