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I have one doubt on the prisma query, how can I do type casting in the prisma query,
In my case, I need to perform where query against the datetime values, Here the input will be either one of the strings or a timestamp. if the input is a timestamp value, then it works fine, if the value is not a timestamp value, then the prisma throws an error.
return this.DB.$transaction([
this.User.findMany({
take,
skip,
where: {
created_at:{ equals: '2022-10-03T05:24:04.712Z'}
}
}),
this.User.count({
where: { ...queries, ...columnQuery }
})
])
In the above case, the query works fine, if I provide the string instead of the timestamp it throw an error
return this.DB.$transaction([
this.User.findMany({
take,
skip,
where: {
created_at:{equals: '12'}
}
}),
this.User.count({
where: { ...queries, ...columnQuery }
})
])
Here the order by input is 12, if the value is not a time stamp type, I also need to perform the where query. In my understaing, if we perform the typecasting to string against created_at column, we can perform filter query in typestamp datatype column, even though the input is not a timestamp type
friends can you help me to fix this ?
From the docs:
You can also chain multiple where() methods to create more specific queries (logical AND).
How can I perform an OR query?
Example:
Give me all documents where the field status is open OR upcoming
Give me all documents where the field status == open OR createdAt <= <somedatetime>
OR isn't supported as it's hard for the server to scale it (requires keeping state to dedup). The work around is to issue 2 queries, one for each condition, and dedup on the client.
Edit (Nov 2019):
Cloud Firestore now supports IN queries which are a limited type of OR query.
For the example above you could do:
// Get all documents in 'foo' where status is open or upcmoming
db.collection('foo').where('status','in',['open','upcoming']).get()
However it's still not possible to do a general OR condition involving multiple fields.
With the recent addition of IN queries, Firestore supports "up to 10 equality clauses on the same field with a logical OR"
A possible solution to (1) would be:
documents.where('status', 'in', ['open', 'upcoming']);
See Firebase Guides: Query Operators | in and array-contains-any
suggest to give value for status as well.
ex.
{ name: "a", statusValue = 10, status = 'open' }
{ name: "b", statusValue = 20, status = 'upcoming'}
{ name: "c", statusValue = 30, status = 'close'}
you can query by ref.where('statusValue', '<=', 20) then both 'a' and 'b' will found.
this can save your query cost and performance.
btw, it is not fix all case.
I would have no "status" field, but status related fields, updating them to true or false based on request, like
{ name: "a", status_open: true, status_upcoming: false, status_closed: false}
However, check Firebase Cloud Functions. You could have a function listening status changes, updating status related properties like
{ name: "a", status: "open", status_open: true, status_upcoming: false, status_closed: false}
one or the other, your query could be just
...where('status_open','==',true)...
Hope it helps.
This doesn't solve all cases, but for "enum" fields, you can emulate an "OR" query by making a separate boolean field for each enum-value, then adding a where("enum_<value>", "==", false) for every value that isn't part of the "OR" clause you want.
For example, consider your first desired query:
Give me all documents where the field status is open OR upcoming
You can accomplish this by splitting the status: string field into multiple boolean fields, one for each enum-value:
status_open: bool
status_upcoming: bool
status_suspended: bool
status_closed: bool
To perform your "where status is open or upcoming" query, you then do this:
where("status_suspended", "==", false).where("status_closed", "==", false)
How does this work? Well, because it's an enum, you know one of the values must have true assigned. So if you can determine that all of the other values don't match for a given entry, then by deduction it must match one of the values you originally were looking for.
See also
in/not-in/array-contains-in: https://firebase.google.com/docs/firestore/query-data/queries#in_and_array-contains-any
!=: https://firebase.googleblog.com/2020/09/cloud-firestore-not-equal-queries.html
I don't like everyone saying it's not possible.
it is if you create another "hacky" field in the model to build a composite...
for instance, create an array for each document that has all logical or elements
then query for .where("field", arrayContains: [...]
you can bind two Observables using the rxjs merge operator.
Here you have an example.
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/observable/merge';
...
getCombinatedStatus(): Observable<any> {
return Observable.merge(this.db.collection('foo', ref => ref.where('status','==','open')).valueChanges(),
this.db.collection('foo', ref => ref.where('status','==','upcoming')).valueChanges());
}
Then you can subscribe to the new Observable updates using the above method:
getCombinatedStatus.subscribe(results => console.log(results);
I hope this can help you, greetings from Chile!!
We have the same problem just now, luckily the only possible values for ours are A,B,C,D (4) so we have to query for things like A||B, A||C, A||B||C, D, etc
As of like a few months ago firebase supports a new query array-contains so what we do is make an array and we pre-process the OR values to the array
if (a) {
array addObject:#"a"
}
if (b) {
array addObject:#"b"
}
if (a||b) {
array addObject:#"a||b"
}
etc
And we do this for all 4! values or however many combos there are.
THEN we can simply check the query [document arrayContains:#"a||c"] or whatever type of condition we need.
So if something only qualified for conditional A of our 4 conditionals (A,B,C,D) then its array would contain the following literal strings: #["A", "A||B", "A||C", "A||D", "A||B||C", "A||B||D", "A||C||D", "A||B||C||D"]
Then for any of those OR combinations we can just search array-contains on whatever we may want (e.g. "A||C")
Note: This is only a reasonable approach if you have a few number of possible values to compare OR with.
More info on Array-contains here, since it's newish to firebase docs
If you have a limited number of fields, definitely create new fields with true and false like in the example above. However, if you don't know what the fields are until runtime, you have to just combine queries.
Here is a tags OR example...
// the ids of students in class
const students = [studentID1, studentID2,...];
// get all docs where student.studentID1 = true
const results = this.afs.collection('classes',
ref => ref.where(`students.${students[0]}`, '==', true)
).valueChanges({ idField: 'id' }).pipe(
switchMap((r: any) => {
// get all docs where student.studentID2...studentIDX = true
const docs = students.slice(1).map(
(student: any) => this.afs.collection('classes',
ref => ref.where(`students.${student}`, '==', true)
).valueChanges({ idField: 'id' })
);
return combineLatest(docs).pipe(
// combine results by reducing array
map((a: any[]) => {
const g: [] = a.reduce(
(acc: any[], cur: any) => acc.concat(cur)
).concat(r);
// filter out duplicates by 'id' field
return g.filter(
(b: any, n: number, a: any[]) => a.findIndex(
(v: any) => v.id === b.id) === n
);
}),
);
})
);
Unfortunately there is no other way to combine more than 10 items (use array-contains-any if < 10 items).
There is also no other way to avoid duplicate reads, as you don't know the ID fields that will be matched by the search. Luckily, Firebase has good caching.
For those of you that like promises...
const p = await results.pipe(take(1)).toPromise();
For more info on this, see this article I wrote.
J
OR isn't supported
But if you need that you can do It in your code
Ex : if i want query products where (Size Equal Xl OR XXL : AND Gender is Male)
productsCollectionRef
//1* first get query where can firestore handle it
.whereEqualTo("gender", "Male")
.addSnapshotListener((queryDocumentSnapshots, e) -> {
if (queryDocumentSnapshots == null)
return;
List<Product> productList = new ArrayList<>();
for (DocumentSnapshot snapshot : queryDocumentSnapshots.getDocuments()) {
Product product = snapshot.toObject(Product.class);
//2* then check your query OR Condition because firestore just support AND Condition
if (product.getSize().equals("XL") || product.getSize().equals("XXL"))
productList.add(product);
}
liveData.setValue(productList);
});
For Flutter dart language use this:
db.collection("projects").where("status", whereIn: ["public", "unlisted", "secret"]);
actually I found #Dan McGrath answer working here is a rewriting of his answer:
private void query() {
FirebaseFirestore db = FirebaseFirestore.getInstance();
db.collection("STATUS")
.whereIn("status", Arrays.asList("open", "upcoming")) // you can add up to 10 different values like : Arrays.asList("open", "upcoming", "Pending", "In Progress", ...)
.addSnapshotListener(new EventListener<QuerySnapshot>() {
#Override
public void onEvent(#Nullable QuerySnapshot queryDocumentSnapshots, #Nullable FirebaseFirestoreException e) {
for (DocumentSnapshot documentSnapshot : queryDocumentSnapshots) {
// I assume you have a model class called MyStatus
MyStatus status= documentSnapshot.toObject(MyStatus.class);
if (status!= null) {
//do somthing...!
}
}
}
});
}
I have a mongoose schema where I'm storing a port number. I also have a default value set for the field.
port:{
type:Number,
default:1234
}
If I don't get any value via my API, it gets set to 1234.
However, If someone sends null, it accepts null and saves to database.
Shouldn't it covert null to 1234? null is not a number! Am I understanding it wrong?
I am considering the solution given here, but I dont want to add extra code for something that should work without it (unless I'm wrong and its not supposed to convert null to 1234)
See the comments in this issue:
https://github.com/Automattic/mongoose/issues/2438
null is a valid value for a Date property, unless you specify required. Defaults only get set if the value is undefined, not if its falsy.
(it's about dates but it can be applied to numbers just as well.)
Your options are to either:
add required to the field
add a custom validator that would reject it
use hooks/middleware to fix the issue
You might get away with a pre-save or post-validate (or some other) hook like this:
YourCollection.pre('save', function (next) {
if (this.port === null) {
this.port = undefined;
}
next();
});
but probably you'll have to use something like:
YourCollection.pre('save', function (next) {
if (this.port === null) {
this.port = 1234; // get it from the schema object instead of hardcoding
}
next();
});
See also this answer for some tricks on how to make null trigger default values in function invocation:
Passing in NULL as a parameter in ES6 does not use the default parameter when one is provided
This is unfortunate that Mongoose cannot be configured to tread null as undefined (with some "not-null" parameter or something like that) because it is sometimes the case that you work with data that you got in a request as JSON and it can sometimes convert undefined to null:
> JSON.parse(JSON.stringify([ undefined ]));
[ null ]
or even add null values where there was no (explicit) undefined:
> JSON.parse(JSON.stringify([ 1,,2 ]));
[ 1, null, 2 ]
As explained in mongoose official docs here
Number
To declare a path as a number, you may use either the Number global constructor or the string 'Number'.
const schema1 = new Schema({ age: Number }); // age will be cast to a Number
const schema2 = new Schema({ age: 'Number' }); // Equivalent
const Car = mongoose.model('Car', schema2);
There are several types of values that will be successfully cast to a Number.
new Car({ age: '15' }).age; // 15 as a Number
new Car({ age: true }).age; // 1 as a Number
new Car({ age: false }).age; // 0 as a Number
new Car({ age: { valueOf: () => 83 } }).age; // 83 as a Number
If you pass an object with a valueOf() function that returns a Number, Mongoose will call it and assign the returned value to the path.
The values null and undefined are not cast.
NaN, strings that cast to NaN, arrays, and objects that don't have a valueOf() function will all result in a CastError.
I have a array which has list of string
Example : ["one","two","three","four"]
Also I have a sample dynamodb structure given below
id(primary key) | status
one | completed
three | completed
five | completed
six | Inprogress
I need to check the string value with the dynamodb primary key whether it is already exist in dynamodb or not(Doing this logic in nodejs).
If the string value is already exist in dynamodb don't add it in new array and if its not exist in dynamodb need to add the string in the new array.
In the above example data expeced result is : ["two","four"].
Please let me know how can we check the existing data in dynamodb.
Thanks in advance
I'm not sure I fully understand your question, but I think you're looking for either the Exists parameter in a dynamodb putItem request or a conditional operator.
To paraphrase the documentation, it's possible to assert that the record does not exist when performing a put-operation:
"If Exists is false, DynamoDB assumes that the attribute value does
not exist in the table. If in fact the value does not exist, then the
assumption is valid and the operation succeeds. If the value is found,
despite the assumption that it does not exist, the operation fails
with a ConditionalCheckFailedException."
Similarly, it should be possible to write more complicated assertions on the operation.
You can accomplish this using ConditionExpressions.
var params = {};
params.TableName = "MyTable";
params.Item = { id : { S : 'one' }, status : { S : 'completed' } },
params.ConditionExpression = '#i <> :val';
params.ExpressionAttributeNames = {'#i' : 'id'};
params.ExpressionAttributeValues = {':val' : "one"};
DynamoDB.putItem(params, function (error, data) { ... });
This will only write to the table if an item with id 'one' does not already exist.
Since you're using nodejs I'd suggest looking into using the vogels library. The same ConditionExpression can be written as:
Event.create({id : "one", status : 'completed' }, {overwrite : false}, function (error, acc) { ... });
I am trying cassandra node driver and stuck in problem while inserting a record, it looks like cassandra driver is not able to insert float values.
Problem: When passing int value for insertion in db, api gives following error:
Debug: hapi, internal, implementation, error
ResponseError: Expected 4 or 0 byte int (8)
at FrameReader.readError (/home/gaurav/Gaurav-Drive/code/nodejsWorkspace/cassandraTest/node_modules/cassandra-driver/lib/readers.js:291:13)
at Parser.parseError (/home/gaurav/Gaurav-Drive/code/nodejsWorkspace/cassandraTest/node_modules/cassandra-driver/lib/streams.js:185:45)
at Parser.parseBody (/home/gaurav/Gaurav-Drive/code/nodejsWorkspace/cassandraTest/node_modules/cassandra-driver/lib/streams.js:167:19)
at Parser._transform (/home/gaurav/Gaurav-Drive/code/nodejsWorkspace/cassandraTest/node_modules/cassandra-driver/lib/streams.js:101:10)
at Parser.Transform._read (_stream_transform.js:179:10)
at Parser.Transform._write (_stream_transform.js:167:12)
at doWrite (_stream_writable.js:225:10)
at writeOrBuffer (_stream_writable.js:215:5)
at Parser.Writable.write (_stream_writable.js:182:11)
at write (_stream_readable.js:601:24)
I am trying to execute following query from code:
INSERT INTO ragchews.user
(uid ,iid ,jid ,jpass ,rateCount ,numOfratedUser ,hndl ,interests ,locX ,locY ,city )
VALUES
('uid_1',{'iid1'},'jid_1','pass_1',25, 10, {'NEX1231'}, {'MUSIC'}, 21.321, 43.235, 'delhi');
parameter passed to execute() is
var params = [uid, iid, jid, jpass, rateCount, numOfratedUser, hndl, interest, locx, locy, city];
where
var locx = 32.09;
var locy = 54.90;
and call to execute looks like:
var addUserQuery = 'INSERT INTO ragchews.user (uid ,iid ,jid ,jpass ,rateCount ,numOfratedUser ,hndl ,interests ,locX ,locY ,city) VALUES (?,?,?,?,?,?,?,?,?,?,?);';
var addUser = function(user, cb){
console.log(user);
client.execute(addUserQuery, user, function(err, result){
if(err){
throw err;
}
cb(result);
});
};
CREATE TABLE ragchews.user(
uid varchar,
iid set<varchar>,
jid varchar,
jpass varchar,
rateCount int,
numOfratedUser int,
hndl set<varchar>,
interests set<varchar>,
locX float,
locY float,
city varchar,
favorite map<varchar, varchar>,
PRIMARY KEY(uid)
);
P.S
Some observations while trying to understand the issue:
Since it seems, problem is with float so i changed type float (of locX, locY) to int and re-run the code. Same error persist. Hence, it is not problem associated specifically to float CQL type.
Next, i attempted to remove all int from the INSERT query and attempted to insert only non-numeric values. This attempt successfully inputted the value into db. Hence it looks like now that, this problem may be associated with numeric types.
Following words are as it is picked from cassandra node driver data type documentation
When encoding data, on a normal execute with parameters, the driver tries to guess the target type based on the input type. Values of type Number will be encoded as double (as Number is double / IEEE 754 value).
Consider the following example:
var key = 1000;
client.execute('SELECT * FROM table1 where key = ?', [key], callback);
If the key column is of type int, the execution fails. There are two possible ways to avoid this type of problem:
Prepare the data (recommended) - prepare the query before execution
client.execute('SELECT * FROM table1 where key = ?', [key], { prepare : true }, callback);
Hinting the target types - Hint: the first parameter is an integer`
client.execute('SELECT * FROM table1 where key = ?', [key], { hints : ['int'] }, callback);
If you are dealing with batch update then this issue may be of your interest.