I want to send in response some data according to searching by query parameters (using .find function of mongoose) from the client side. What do I need to do is a search according to the parameters received?
What I mean is :
I may receive
localhost:5000/admin/customers?customer_id=1&customer_email=abc#gmail.com
I could have used this code to send results according to this query :
Customer.find({
customer_id = req.query.customer_id,
customer_email = req.query.customer_email,
}, (err,docs)=> {
res.json(docs);
})
or
just
localhost:5000/admin/customers?customer_id=1
I could have used this code to send results according to this query :
Customer.find({
customer_id = req.query.customer_id
}, (err,docs)=> {
res.json(docs);
})
or
may be
localhost:5000/admin/customers?no_of_items_purchased=15
I could have used this code to send results according to this query :
Customer.find({
no_of_items_purchased = req.query.no_of_items_purchased
}, (err,docs)=> {
res.json(docs);
})
But what I want is to use .find function on anything received from query params. Like a general code to achieve this.
PS: Also please help with : "How to filter req.query so it only contains fields that are defined in your schema ?"
You can create a query variable to keep the field that you want to filter.
Suppose that your Customer model structure is:
{
customer_id: ...,
customer_name: ...,
customer_email: ...,
no_of_items_purchased: ...
}
Then your code will be:
let {customer_id, customer_name, customer_email, no_of_items_purchased} = req.query;
let query = {};
if (customer_id != null) query.customer_id = customer_id;
if (customer_name != null) query.customer_name = customer_name;
if (customer_email != null) query.customer_email = customer_email;
if (no_of_items_purchased != null) query.no_of_items_purchased = no_of_items_purchased;
let result = await Customer.find(query);
Just pass request.query as a parameter directly on find method:
Customer.find(request.query)
Related
I'm currently writing a small API for a cooking app. I have a Recipe model and would like to implement sorting by columns based on the req Parameter given.
I'd like to sort by whatever is passed in the api call. the select parameter works perfectly fine, I can select the columns to be displayed but when I try to sort anything (let's say by rating) the return does sort but I'm not sure what it does sort by.
The code i'm using:
query = Recipe.find(JSON.parse(queryStr));
if(req.query.select){
const fields = req.query.select.split(',').join(' ');
query = query.select(fields);
}
if(req.query.sort){
const sortBy = req.query.sort.split(',').join(' ');
query = query.sort({ sortBy: 1 });
} else {
query = query.sort({ _id: -1 });
}
The result, when no sorting is set: https://pastebin.com/rPLv8n5s
vs. the result when I pass &sort=rating: https://pastebin.com/7eYwAvQf
also, when sorting my name the result is also mixed up.
You are not using the value of sortBy but the string "sortBy". You will need to create an object that has the rating as an object key.
You need the sorting object to look like this.
{
rating: 1
}
You can use something like this so it will be dynamic.
if(req.query.sort){
const sortByKey = req.query.sort.split(',').join(' ');
const sortByObj = {};
sortByObj[sortByKey] = 1; // <-- using sortBy as the key
query = query.sort(sortByObj);
} else {
query = query.sort({ _id: -1 });
}
I've a node.js api in which user sends the required fields as an array to be fetched from the mongodb database. I need to find the data of that fields using Find query. I've written forEach statement to loop through that array and got the array elements. But when I try to get the results by inserting the array elements in the query, it doesn't giving the required results. Could any one please help me in resolving the issue by seeing the code below?
templateLevelGraphData: async function(tid,payload){
let err, templateData, respData = [], test, currentValue;
[err,templateData] = await to(Template.findById(tid));
var templateId = templateData.templateId;
payload.variables.forEach(async data=>{
console.log(data); //data has the array elements like variables=["humidity"]
[err, currentValue] = await to(mongoose.connection.db.collection(templateId).find({},{data:1}).sort({"entryDayTime":-1}).limit(1).toArray());
console.log(currentValue);
});
return "success";
}
The expected output is,
[ { humidity: 36 } ]
But I'm getting only _id like,
[ { _id: 5dce3a2df89ab63ee4d95495 } ]
I think data is not applying in the query. But I'm printing the data in the console where it's giving the correct results by displaying the array elements like, humidity. What I need to do to make it work?
When you are passing {data: 1} you are passing an array where is expecting name of column.
You have to create an object where the keys are going to be the elements of the array and set them to 1.
const projection = data.reduce((a,b) => (a[b]=1, a), {});
[...] .find({}, projection) [...]
Actually I got the solution.
for(let i=0;i<payload.variables.length;i++){
var test = '{"'+ payload.variables[i] +'":1,"_id":0}';
var query = JSON.parse(test);
[err, currentValue] = await to(mongoose.connection.db.collection(templateId).find({"deviceId":deviceId},query).sort({"entryDayTime":-1}).limit(1).toArray());
console.log(currentValue); //It's giving the solution
}
I don't know whether I have too much expectation from mongodb, but I have a question here.
Is it possible to customize the query according to a boolean parameter? Firstly, I have looked https://docs.mongodb.com/manual/reference/operator/aggregation/cond/.
But didn't find an example where the condition is up to a another parameter.
Here let me clarify by an example;
Let assume I have a flag parameter. I want to execute two similar queries based on whether its value is true or false.
document is like;
{
"name" : "alex",
"age" : NumberInt(21)
}
{
"name" : "felix",
"age" : NumberInt(14)
}
To be able to look the condition I can break them into two different query as;
if(flag){
db.collection.find({age: "18"})
}else{
db.collection.find({age: "21"})
}
I am looking for something like this;
db.collection.aggregate([
{$cond: [flag,{$match: {age: "18"}} ,{$match: {age: "21"}}]}
])
But this throws an error which is not a surprise.
Is it possible to use $cond and execute two different query? Can a parameter pass in the $cond?
You can generate query first based on your condition then execute that query one time.
var query = {};
if(flag){
query.age = 18;
}else{
query.age = 21;
}
db.collection.find(query, function(err, result) {
if(err) {
// return error
}
console.log(result);
// return result
})
I have a user table with a field username. I need to write something equivalent to this in dynamo db: Select * from user where username in('a','b','c');
Adding more from code prosepective i have usernames in an array say var arr=['a','b','c'];
I so far tried this which is giving me zero result
this.dynamo.client.scanAsync({
TableName: this.dynamo.table('users'),
FilterExpression: 'username IN (:list)',
ExpressionAttributeValues: {
':list': arr.toString()
}
}).then((response) => {
console.log(response);
return {
userFriends: result.Item.friends
};
});
When I pass one element in array it give me result searching passed single element in user table but its not working with more than one element in array.
The individual users should be given as comma separated String variables. JavaScript array is equivalent to List in AWS DynamoDB data type. The DynamoDB can't compare the String data type in database with List attribute (i.e. Array in JavaScript).
var params = {
TableName : "Users",
FilterExpression : "username IN (:user1, :user2)",
ExpressionAttributeValues : {
":user1" : "john",
":user2" : "mike"
}
};
Construct the object from array for FilterExpression:-
Please refer the below code for forming the object dynamically based on Array value.
var titleValues = ["The Big New Movie 2012", "The Big New Movie"];
var titleObject = {};
var index = 0;
titleValues.forEach(function(value) {
index++;
var titleKey = ":titlevalue"+index;
titleObject[titleKey.toString()] = value;
});
var params = {
TableName : "Movies",
FilterExpression : "title IN ("+Object.keys(titleObject).toString()+ ")",
ExpressionAttributeValues : titleObject
};
Note:-
I don't think IN clause with 1000s of usernames is a good idea in terms of performance.
I'm building an API using node express and mongodb, with mongoose.
I have a post resource that handles user posts, and would like to be able to perform various queries on the post resource.
For instance I have a functions as that returns all posts as follows:
// Gets a list of Posts
exports.index = function(req, res) {
console.log(req.query);
Post.findAsync()
.then(mUtil.responseWithResult(res))
.catch(mUtil.handleError(res));
};
I looking for a good way of processing any additional query params that might come with the request.
/posts will return all posts, but /posts?user=12 will return posts by user with id 12 and /posts?likes=12 will return posts with 12 or more likes.
How can I check for and apply the these query params to filter and return the results since they may or may not be present.
Thanks ;)
If user=12 means "users with id 12", how does likes=12 mean "likes greater than 12"? You need to be more descriptive with your queries. You can do that by passing an array of objects. Send your query in a way that can be interpreted like this:
var filters = [
{
param: "likes",
type: "greater"
value: 12
},
{
param: "user",
type: "equal",
value: "12"
}]
var query = Post.find();
filters.forEach(function(filter) {
if (filter.type === "equal") {
query.where(filter.param).equals(filter.value);
}
else if (filter.type === "greater") {
query.where(filter.param).gt(filter.value);
}
// etc,,,
})
query.exec(callback);