Let's say we query the server with this request, we only want to get the following user's Email, My current implementation requests the whole User object from the MongoDB, which I can imagine is extremely inefficient.
GQL
{
user(id:"34567345637456") {
email
}
}
How would you go about creating a MongoDB filter that would only return those Specified Fields? E.g,
JS object
{
"email": 1
}
My current server is running Node.js, Fastify and Mercurius
which I can imagine is extremely inefficient.
Doing this task is an advanced feature with many pitfalls. I would suggest starting building a simple extraction that read all the fields. This solution works and does not return any additional field to the client.
The pitfalls are:
nested queries
complex object composition
aliasing
multiple queries into one request
Here an example that does what you are looking for.
It manages aliasing and multiple queries.
const Fastify = require('fastify')
const mercurius = require('mercurius')
const app = Fastify({ logger: true })
const schema = `
type Query {
select: Foo
}
type Foo {
a: String
b: String
}
`
const resolvers = {
Query: {
select: async (parent, args, context, info) => {
const currentQueryName = info.path.key
// search the input query AST node
const selection = info.operation.selectionSet.selections.find(
(selection) => {
return (
selection.name.value === currentQueryName ||
selection.alias.value === currentQueryName
)
}
)
// grab the fields requested by the user
const project = selection.selectionSet.selections.map((selection) => {
return selection.name.value
})
// do the query using the projection
const result = {}
project.forEach((fieldName) => {
result[fieldName] = fieldName
})
return result
},
},
}
app.register(mercurius, {
schema,
resolvers,
graphiql: true,
})
app.listen(3000)
Call it using:
query {
one: select {
a
}
two: select {
a
aliasMe:b
}
}
Returns
{
"data": {
"one": {
"a": "a"
},
"two": {
"a": "a",
"aliasMe": "b"
}
}
}
Expanding from #Manuel Spigolon original answer, where he stated that one of the pitfalls of his implementation is that it doesn't work on nested queries and 'multiple queries into one request' which this implementation seeks to fix.
function formFilter(context:any) {
let filter:any = {};
let getValues = (selection:any, parentObj?:string[]) => {
//selection = labelSelection(selection);
selection.map((selection:any) => {
// Check if the parentObj is defined
if(parentObj)
// Merge the two objects
_.merge(filter, [...parentObj, null].reduceRight((obj, next) => {
if(next === null) return ({[selection.name?.value]: 1});
return ({[next]: obj});
}, {}));
// Check for a nested selection set
if(selection.selectionSet?.selections !== undefined){
// If the selection has a selection set, then we need to recurse
if(!parentObj) getValues(selection.selectionSet?.selections, [selection.name.value]);
// If the selection is nested
else getValues(selection.selectionSet?.selections, [...parentObj, selection.name.value]);
}
});
}
// Start the recursive function
getValues(context.operation.selectionSet.selections);
return filter;
}
Input
{
role(id: "61f1ccc79623d445bd2f677f") {
name
users {
user_name
_id
permissions {
roles
}
}
permissions
}
}
Output (JSON.stringify)
{
"role":{
"name":1,
"users":{
"user_name":1,
"_id":1,
"permissions":{
"roles":1
}
},
"permissions":1
}
}
Could anyone please guide me how to achieve the below challenge which I am facing?
I have thousands of mock API request response JSON files. They are deeply nested, and they all are structured differently. I need to add/update/delete entry at the specfic location where the condition match which will be provided by user. I am not sure how to approach this problem? I have tried doing something like below. I am asking user for path for where to start looking. But this will increase time as user has to look for path in all file and pass that info to api. below code work upto 2 level only. need to search full tree where all user provides conditions matches, and at that place, I need to add/update/delete data. I took condition as an array of objects.
Draft Code
const _ = require("lodash");
const file = "./sample.json";
const actions = ["add", "delete", "update"];
const consumer = (file, key, where, data, action) => {
try {
const act = action.toLowerCase();
if(!actions.includes(act) throw new Error("invalid action provided");
if(_.isArray(where) && _.every(where, _.isObject())) throw new Error("no where clause condition provided");
let content = require(file);
let typeKeyContent = null;
let keyContent = _.get(content, key);
if(!keyContent) throw new Error("invalid key");
if(_.isArray(keyContent)) {
typeKeyContent = "array"
} else if (_.isObject(keyContent)) {
typeKeyContent = "object"
}
switch (act) {
case "add":
if (typeKeyContent === "array") {
// array logic
for (let i = 0; i < keyContent.length; i++) {
const result = where.every(element => {
for (let key in element) {
return keyContent[key] && element[key] === keyContent[key];
}
});
if (!result) {
console.log("attributes matching -> ", result);
return;
}
keyContent[i] = {...keyContent[i], ...data }
}
let newcontent = _.set(content, key, keyContent);
console.log("newcontent -> \n",JSON.stringify(newcontent, null, 2));
return;
}
const result = where.every(element => {
for (let key in element) {
return keyContent[key] && element[key] === keyContent[key];
}
});
if (!result) {
console.log("attributes matching -> ", result);
return;
}
keyContent = { ...keyContent, ...data };
let newcontent = _.set(content, key, keyContent);
console.log("newcontent -> \n",JSON.stringify(newcontent, null, 2));
// TODO :: store back in json file
break;
default:
console.log("reached default case");
return;
}
} catch(err) {
console.log("ERROR :: CONSUMER ::", error);
}
}
// AND based condition only
const conditions = [
{ name: "Essential Large" },
{ selected: true }
];
const newdata = { description: "our best service" } // wants to add new prop
consumer(file, "selected_items.essential", conditions, newdata, "add");
sample json
{
"status": 200,
"request": {},
"response": {
"ffs": false,
"customer": {
"customer_id": 1544248,
"z_cx_id": 123456
},
"selected_items": {
"essential": [
{
"id": 4122652,
"name": "Essential Large",
"selected": true,
"description": "our best service" // will be added
},
{
"id": 4122653,
"name": "Essential Large",
"selected": true,
"description": "our best service" // will be added
}
]
},
"service_partner": {
"id": 3486,
"name": "Some String",
"street": "1234 King St."
},
"subject": "Project",
"description": "Issue: (copy/paste service request details here Required"
}
}
So you want to go through every key of a nested object right?
function forEvery(object,fn){
//obj is the object, fn is the function
//this function should go through each item in an object loaded from JSON string
//fn takes in 3 arguments: current element, that element's parent, level of depth(starts at 1)
var arr=[]
function recurse(obj,map,depth){
Object.keys(obj).forEach((a,i)=>{
fn(obj[a],obj,a,depth) //because fn can affect the object so the if statement should after not before ;-;
if(typeof obj[a]=="object"&&obj[a]!=null){ //if nested value is another object
map.push(a); arr.push(map)
recurse(obj[a],[...map],depth+1)
}
})
}
recurse(object,[],1)
}
//usage would be like:
//let customerCondition=/*some logic here*/
//let testObj=JSON.parse( (require('fs')).readFileSync('dirToSomeFile.json') )
forEvery(testObj,customerCondition)
Here's a live example
let testObj={"status":200,"request":{},"response":{"ffs":false,"customer":{"customer_id":1544248,"z_cx_id":123456},"selected_items":{"essential":[{"id":4122652,"name":"Essential Large","selected":true},{"id":4122653,"name":"Essential Medium","selected":false}]},"service_partner":{"id":3486,"name":"Some String","street":"1234 King St."},"subject":"Project","description":"Issue: (copy/paste service request details here Required"}}
function forEvery(object,fn){
//obj is the object, fn is the function
//this function should go through each item in an object loaded from JSON string
//fn takes in 3 arguments: current element, that element's parent, level of depth(starts at 1)
var arr=[]
function recurse(obj,map,depth){
Object.keys(obj).forEach((a,i)=>{
fn(obj[a],obj,a,depth) //because fn can affect the object so the if statement should after not before ;-;
if(typeof obj[a]=="object"&&obj[a]!=null){ //if nested value is another object
map.push(a); arr.push(map)
recurse(obj[a],[...map],depth+1)
}
})
}
recurse(object,[],1)
}
//example usage
let userQuery=[{ name: "Essential Large" },{ selected: true }]; //the user query in the format you gave
let userCondition={} //assuming each key across userQuery is unique, I set a model object for comparisons later on
userQuery.forEach(obj=>{ //I fill the model object :D
Object.keys(obj).forEach(key=>{
userCondition[key]=obj[key]
})
})
let testFn=(elem,parent,key,depth)=>{
//I use comparisons with the model object
let condition=typeof elem!="object"?false:
Object.keys(userCondition)
.every(item=>userCondition[item]==elem[item])
//true if matches user condition(meaning elem must be an object), false otherwise
if(condition){
console.log(parent[key],"will now be deleted")
delete(parent[key]) //deletion example(if user conditions match)
}
}
forEvery(testObj,testFn)
console.log("and the changed object looks like",testObj)
Let me how to find a json in javascript.
Sample Json:
{
"Employees" : [
{
"userId":"rirani",
"jobTitleName":"Developer",
"preferredFullName":"Romin Irani",
"employeeCode":"E1",
"region":"CA",
"phoneNumber":"408-1234567",
"emailAddress":"romin.k.irani#gmail.com"
},
{
"userId":"nirani",
"jobTitleName":"Developer",
"preferredFullName":"Neil Irani",
"employeeCode":"E2",
"region":"CA",
"phoneNumber":"408-1111111",
"emailAddress":"neilrirani#gmail.com"
}
]
]
}
the above json i want find particular userId based on employeeCode,emailAddress ad PhoneNumber. currently i am doing like below
for(var i=0; i<json.length;i++){
if((employeeCode==code)&&(emailAddress ==email)&&(PhoneNumber==phone)){
//here i am getting userId
}
}
I want know if this is the correct way. If it is small json load it ok. but if it's large scale of data what i have to do.
You can simply use the map function on the Employee array:
var data = {
"Employees" : [
{
"userId":"rirani",
"jobTitleName":"Developer",
"preferredFullName":"Romin Irani",
"employeeCode":"E1",
"region":"CA",
"phoneNumber":"408-1234567",
"emailAddress":"romin.k.irani#gmail.com"
},
{
"userId":"nirani",
"jobTitleName":"Developer",
"preferredFullName":"Neil Irani",
"employeeCode":"E2",
"region":"CA",
"phoneNumber":"408-1111111",
"emailAddress":"neilrirani#gmail.com"
}
]
};
var code ='E2' , email ='neilrirani#gmail.com' , phone = '408-1111111', userId;
data.Employees.map(x=>{
if(x.employeeCode == code && x.phoneNumber == phone && x.emailAddress== email){
userId = x.userId;
}
});
console.log(userId);
You can use find method which accepts a callback provided function applied on every item in the array.
The find() method returns the value of the first element in the array
that satisfies the provided testing function. Otherwise undefined is
returned.
let emailAddress="neilrirani#gmail.com";
let phone="408-1111111";
let code="E2";
let Employees = [
{
"userId":"rirani",
"jobTitleName":"Developer",
"preferredFullName":"Romin Irani",
"employeeCode":"E1",
"region":"CA",
"phoneNumber":"408-1234567",
"emailAddress":"romin.k.irani#gmail.com"
},
{
"userId":"nirani",
"jobTitleName":"Developer",
"preferredFullName":"Neil Irani",
"employeeCode":"E2",
"region":"CA",
"phoneNumber":"408-1111111",
"emailAddress":"neilrirani#gmail.com"
}
];
let employee=Employees.find(function(employee){
return employee.emailAddress==emailAddress && employee.phoneNumber==phone && employee.employeeCode==code;
});
console.log(employee.userId);
I'd like to get the names of all the keys in a MongoDB collection.
For example, from this:
db.things.insert( { type : ['dog', 'cat'] } );
db.things.insert( { egg : ['cat'] } );
db.things.insert( { type : [] } );
db.things.insert( { hello : [] } );
I'd like to get the unique keys:
type, egg, hello
You could do this with MapReduce:
mr = db.runCommand({
"mapreduce" : "my_collection",
"map" : function() {
for (var key in this) { emit(key, null); }
},
"reduce" : function(key, stuff) { return null; },
"out": "my_collection" + "_keys"
})
Then run distinct on the resulting collection so as to find all the keys:
db[mr.result].distinct("_id")
["foo", "bar", "baz", "_id", ...]
With Kristina's answer as inspiration, I created an open source tool called Variety which does exactly this: https://github.com/variety/variety
You can use aggregation with the new $objectToArray aggregation operator in version 3.4.4 to convert all top key-value pairs into document arrays, followed by $unwind and $group with $addToSet to get distinct keys across the entire collection. (Use $$ROOT for referencing the top level document.)
db.things.aggregate([
{"$project":{"arrayofkeyvalue":{"$objectToArray":"$$ROOT"}}},
{"$unwind":"$arrayofkeyvalue"},
{"$group":{"_id":null,"allkeys":{"$addToSet":"$arrayofkeyvalue.k"}}}
])
You can use the following query for getting keys in a single document.
db.things.aggregate([
{"$match":{_id: "<<ID>>"}}, /* Replace with the document's ID */
{"$project":{"arrayofkeyvalue":{"$objectToArray":"$$ROOT"}}},
{"$project":{"keys":"$arrayofkeyvalue.k"}}
])
A cleaned up and reusable solution using pymongo:
from pymongo import MongoClient
from bson import Code
def get_keys(db, collection):
client = MongoClient()
db = client[db]
map = Code("function() { for (var key in this) { emit(key, null); } }")
reduce = Code("function(key, stuff) { return null; }")
result = db[collection].map_reduce(map, reduce, "myresults")
return result.distinct('_id')
Usage:
get_keys('dbname', 'collection')
>> ['key1', 'key2', ... ]
If your target collection is not too large, you can try this under mongo shell client:
var allKeys = {};
db.YOURCOLLECTION.find().forEach(function(doc){Object.keys(doc).forEach(function(key){allKeys[key]=1})});
allKeys;
If you are using mongodb 3.4.4 and above then you can use below aggregation using $objectToArray and $group aggregation
db.collection.aggregate([
{ "$project": {
"data": { "$objectToArray": "$$ROOT" }
}},
{ "$project": { "data": "$data.k" }},
{ "$unwind": "$data" },
{ "$group": {
"_id": null,
"keys": { "$addToSet": "$data" }
}}
])
Here is the working example
Try this:
doc=db.thinks.findOne();
for (key in doc) print(key);
Using python. Returns the set of all top-level keys in the collection:
#Using pymongo and connection named 'db'
reduce(
lambda all_keys, rec_keys: all_keys | set(rec_keys),
map(lambda d: d.keys(), db.things.find()),
set()
)
Here is the sample worked in Python:
This sample returns the results inline.
from pymongo import MongoClient
from bson.code import Code
mapper = Code("""
function() {
for (var key in this) { emit(key, null); }
}
""")
reducer = Code("""
function(key, stuff) { return null; }
""")
distinctThingFields = db.things.map_reduce(mapper, reducer
, out = {'inline' : 1}
, full_response = True)
## do something with distinctThingFields['results']
I am surprise, no one here has ans by using simple javascript and Set logic to automatically filter the duplicates values, simple example on mongo shellas below:
var allKeys = new Set()
db.collectionName.find().forEach( function (o) {for (key in o ) allKeys.add(key)})
for(let key of allKeys) print(key)
This will print all possible unique keys in the collection name: collectionName.
I think the best way do this as mentioned here is in mongod 3.4.4+ but without using the $unwind operator and using only two stages in the pipeline. Instead we can use the $mergeObjects and $objectToArray operators.
In the $group stage, we use the $mergeObjects operator to return a single document where key/value are from all documents in the collection.
Then comes the $project where we use $map and $objectToArray to return the keys.
let allTopLevelKeys = [
{
"$group": {
"_id": null,
"array": {
"$mergeObjects": "$$ROOT"
}
}
},
{
"$project": {
"keys": {
"$map": {
"input": { "$objectToArray": "$array" },
"in": "$$this.k"
}
}
}
}
];
Now if we have a nested documents and want to get the keys as well, this is doable. For simplicity, let consider a document with simple embedded document that look like this:
{field1: {field2: "abc"}, field3: "def"}
{field1: {field3: "abc"}, field4: "def"}
The following pipeline yield all keys (field1, field2, field3, field4).
let allFistSecondLevelKeys = [
{
"$group": {
"_id": null,
"array": {
"$mergeObjects": "$$ROOT"
}
}
},
{
"$project": {
"keys": {
"$setUnion": [
{
"$map": {
"input": {
"$reduce": {
"input": {
"$map": {
"input": {
"$objectToArray": "$array"
},
"in": {
"$cond": [
{
"$eq": [
{
"$type": "$$this.v"
},
"object"
]
},
{
"$objectToArray": "$$this.v"
},
[
"$$this"
]
]
}
}
},
"initialValue": [
],
"in": {
"$concatArrays": [
"$$this",
"$$value"
]
}
}
},
"in": "$$this.k"
}
}
]
}
}
}
]
With a little effort, we can get the key for all subdocument in an array field where the elements are object as well.
This works fine for me:
var arrayOfFieldNames = [];
var items = db.NAMECOLLECTION.find();
while(items.hasNext()) {
var item = items.next();
for(var index in item) {
arrayOfFieldNames[index] = index;
}
}
for (var index in arrayOfFieldNames) {
print(index);
}
Maybe slightly off-topic, but you can recursively pretty-print all keys/fields of an object:
function _printFields(item, level) {
if ((typeof item) != "object") {
return
}
for (var index in item) {
print(" ".repeat(level * 4) + index)
if ((typeof item[index]) == "object") {
_printFields(item[index], level + 1)
}
}
}
function printFields(item) {
_printFields(item, 0)
}
Useful when all objects in a collection has the same structure.
To get a list of all the keys minus _id, consider running the following aggregate pipeline:
var keys = db.collection.aggregate([
{ "$project": {
"hashmaps": { "$objectToArray": "$$ROOT" }
} },
{ "$group": {
"_id": null,
"fields": { "$addToSet": "$hashmaps.k" }
} },
{ "$project": {
"keys": {
"$setDifference": [
{
"$reduce": {
"input": "$fields",
"initialValue": [],
"in": { "$setUnion" : ["$$value", "$$this"] }
}
},
["_id"]
]
}
}
}
]).toArray()[0]["keys"];
I know I am late to the party, but if you want a quick solution in python finding all keys (even the nested ones) you could do with a recursive function:
def get_keys(dl, keys=None):
keys = keys or []
if isinstance(dl, dict):
keys += dl.keys()
list(map(lambda x: get_keys(x, keys), dl.values()))
elif isinstance(dl, list):
list(map(lambda x: get_keys(x, keys), dl))
return list(set(keys))
and use it like:
dl = db.things.find_one({})
get_keys(dl)
if your documents do not have identical keys you can do:
dl = db.things.find({})
list(set(list(map(get_keys, dl))[0]))
but this solution can for sure be optimized.
Generally this solution is basically solving finding keys in nested dicts, so this is not mongodb specific.
Based on #Wolkenarchitekt answer: https://stackoverflow.com/a/48117846/8808983, I write a script that can find patterns in all keys in the db and I think it can help others reading this thread:
"""
Python 3
This script get list of patterns and print the collections that contains fields with this patterns.
"""
import argparse
import pymongo
from bson import Code
# initialize mongo connection:
def get_db():
client = pymongo.MongoClient("172.17.0.2")
db = client["Data"]
return db
def get_commandline_options():
description = "To run use: python db_fields_pattern_finder.py -p <list_of_patterns>"
parser = argparse.ArgumentParser(description=description)
parser.add_argument('-p', '--patterns', nargs="+", help='List of patterns to look for in the db.', required=True)
return parser.parse_args()
def report_matching_fields(relevant_fields_by_collection):
print("Matches:")
for collection_name in relevant_fields_by_collection:
if relevant_fields_by_collection[collection_name]:
print(f"{collection_name}: {relevant_fields_by_collection[collection_name]}")
# pprint(relevant_fields_by_collection)
def get_collections_names(db):
"""
:param pymongo.database.Database db:
:return list: collections names
"""
return db.list_collection_names()
def get_keys(db, collection):
"""
See: https://stackoverflow.com/a/48117846/8808983
:param db:
:param collection:
:return:
"""
map = Code("function() { for (var key in this) { emit(key, null); } }")
reduce = Code("function(key, stuff) { return null; }")
result = db[collection].map_reduce(map, reduce, "myresults")
return result.distinct('_id')
def get_fields(db, collection_names):
fields_by_collections = {}
for collection_name in collection_names:
fields_by_collections[collection_name] = get_keys(db, collection_name)
return fields_by_collections
def get_matches_fields(fields_by_collections, patterns):
relevant_fields_by_collection = {}
for collection_name in fields_by_collections:
relevant_fields = [field for field in fields_by_collections[collection_name] if
[pattern for pattern in patterns if
pattern in field]]
relevant_fields_by_collection[collection_name] = relevant_fields
return relevant_fields_by_collection
def main(patterns):
"""
:param list patterns: List of strings to look for in the db.
"""
db = get_db()
collection_names = get_collections_names(db)
fields_by_collections = get_fields(db, collection_names)
relevant_fields_by_collection = get_matches_fields(fields_by_collections, patterns)
report_matching_fields(relevant_fields_by_collection)
if __name__ == '__main__':
args = get_commandline_options()
main(args.patterns)
As per the mongoldb documentation, a combination of distinct
Finds the distinct values for a specified field across a single collection or view and returns the results in an array.
and indexes collection operations are what would return all possible values for a given key, or index:
Returns an array that holds a list of documents that identify and describe the existing indexes on the collection
So in a given method one could do use a method like the following one, in order to query a collection for all it's registered indexes, and return, say an object with the indexes for keys (this example uses async/await for NodeJS, but obviously you could use any other asynchronous approach):
async function GetFor(collection, index) {
let currentIndexes;
let indexNames = [];
let final = {};
let vals = [];
try {
currentIndexes = await collection.indexes();
await ParseIndexes();
//Check if a specific index was queried, otherwise, iterate for all existing indexes
if (index && typeof index === "string") return await ParseFor(index, indexNames);
await ParseDoc(indexNames);
await Promise.all(vals);
return final;
} catch (e) {
throw e;
}
function ParseIndexes() {
return new Promise(function (result) {
let err;
for (let ind in currentIndexes) {
let index = currentIndexes[ind];
if (!index) {
err = "No Key For Index "+index; break;
}
let Name = Object.keys(index.key);
if (Name.length === 0) {
err = "No Name For Index"; break;
}
indexNames.push(Name[0]);
}
return result(err ? Promise.reject(err) : Promise.resolve());
})
}
async function ParseFor(index, inDoc) {
if (inDoc.indexOf(index) === -1) throw "No Such Index In Collection";
try {
await DistinctFor(index);
return final;
} catch (e) {
throw e
}
}
function ParseDoc(doc) {
return new Promise(function (result) {
let err;
for (let index in doc) {
let key = doc[index];
if (!key) {
err = "No Key For Index "+index; break;
}
vals.push(new Promise(function (pushed) {
DistinctFor(key)
.then(pushed)
.catch(function (err) {
return pushed(Promise.resolve());
})
}))
}
return result(err ? Promise.reject(err) : Promise.resolve());
})
}
async function DistinctFor(key) {
if (!key) throw "Key Is Undefined";
try {
final[key] = await collection.distinct(key);
} catch (e) {
final[key] = 'failed';
throw e;
}
}
}
So querying a collection with the basic _id index, would return the following (test collection only has one document at the time of the test):
Mongo.MongoClient.connect(url, function (err, client) {
assert.equal(null, err);
let collection = client.db('my db').collection('the targeted collection');
GetFor(collection, '_id')
.then(function () {
//returns
// { _id: [ 5ae901e77e322342de1fb701 ] }
})
.catch(function (err) {
//manage your error..
})
});
Mind you, this uses methods native to the NodeJS Driver. As some other answers have suggested, there are other approaches, such as the aggregate framework. I personally find this approach more flexible, as you can easily create and fine-tune how to return the results. Obviously, this only addresses top-level attributes, not nested ones.
Also, to guarantee that all documents are represented should there be secondary indexes (other than the main _id one), those indexes should be set as required.
We can achieve this by Using mongo js file. Add below code in your getCollectionName.js file and run js file in the console of Linux as given below :
mongo --host 192.168.1.135 getCollectionName.js
db_set = connect("192.168.1.135:27017/database_set_name"); // for Local testing
// db_set.auth("username_of_db", "password_of_db"); // if required
db_set.getMongo().setSlaveOk();
var collectionArray = db_set.getCollectionNames();
collectionArray.forEach(function(collectionName){
if ( collectionName == 'system.indexes' || collectionName == 'system.profile' || collectionName == 'system.users' ) {
return;
}
print("\nCollection Name = "+collectionName);
print("All Fields :\n");
var arrayOfFieldNames = [];
var items = db_set[collectionName].find();
// var items = db_set[collectionName].find().sort({'_id':-1}).limit(100); // if you want fast & scan only last 100 records of each collection
while(items.hasNext()) {
var item = items.next();
for(var index in item) {
arrayOfFieldNames[index] = index;
}
}
for (var index in arrayOfFieldNames) {
print(index);
}
});
quit();
Thanks #ackuser
Following the thread from #James Cropcho's answer, I landed on the following which I found to be super easy to use. It is a binary tool, which is exactly what I was looking for:
mongoeye.
Using this tool it took about 2 minutes to get my schema exported from command line.
I know this question is 10 years old but there is no C# solution and this took me hours to figure out. I'm using the .NET driver and System.Linq to return a list of the keys.
var map = new BsonJavaScript("function() { for (var key in this) { emit(key, null); } }");
var reduce = new BsonJavaScript("function(key, stuff) { return null; }");
var options = new MapReduceOptions<BsonDocument, BsonDocument>();
var result = await collection.MapReduceAsync(map, reduce, options);
var list = result.ToEnumerable().Select(item => item["_id"].ToString());
This one lines extracts all keys from a collection into a comma separated sorted string:
db.<collection>.find().map((x) => Object.keys(x)).reduce((a, e) => {for (el of e) { if(!a.includes(el)) { a.push(el) } }; return a}, []).sort((a, b) => a.toLowerCase() > b.toLowerCase()).join(", ")
The result of this query typically looks like this:
_class, _id, address, city, companyName, country, emailId, firstName, isAssigned, isLoggedIn, lastLoggedIn, lastName, location, mobile, printName, roleName, route, state, status, token
I extended Carlos LM's solution a bit so it's more detailed.
Example of a schema:
var schema = {
_id: 123,
id: 12,
t: 'title',
p: 4.5,
ls: [{
l: 'lemma',
p: {
pp: 8.9
}
},
{
l: 'lemma2',
p: {
pp: 8.3
}
}
]
};
Type into the console:
var schemafy = function(schema, i, limit) {
var i = (typeof i !== 'undefined') ? i : 1;
var limit = (typeof limit !== 'undefined') ? limit : false;
var type = '';
var array = false;
for (key in schema) {
type = typeof schema[key];
array = (schema[key] instanceof Array) ? true : false;
if (type === 'object') {
print(Array(i).join(' ') + key+' <'+((array) ? 'array' : type)+'>:');
schemafy(schema[key], i+1, array);
} else {
print(Array(i).join(' ') + key+' <'+type+'>');
}
if (limit) {
break;
}
}
}
Run:
schemafy(db.collection.findOne());
Output
_id <number>
id <number>
t <string>
p <number>
ls <object>:
0 <object>:
l <string>
p <object>:
pp <number>
I was trying to write in nodejs and finally came up with this:
db.collection('collectionName').mapReduce(
function() {
for (var key in this) {
emit(key, null);
}
},
function(key, stuff) {
return null;
}, {
"out": "allFieldNames"
},
function(err, results) {
var fields = db.collection('allFieldNames').distinct('_id');
fields
.then(function(data) {
var finalData = {
"status": "success",
"fields": data
};
res.send(finalData);
delteCollection(db, 'allFieldNames');
})
.catch(function(err) {
res.send(err);
delteCollection(db, 'allFieldNames');
});
});
After reading the newly created collection "allFieldNames", delete it.
db.collection("allFieldNames").remove({}, function (err,result) {
db.close();
return;
});
I have 1 simpler work around...
What you can do is while inserting data/document into your main collection "things" you must insert the attributes in 1 separate collection lets say "things_attributes".
so every time you insert in "things", you do get from "things_attributes" compare values of that document with your new document keys if any new key present append it in that document and again re-insert it.
So things_attributes will have only 1 document of unique keys which you can easily get when ever you require by using findOne()