In non Meteor Server-Side calls to mongodb it is possible make the following chained-option call to the database
collection.find( { myField: { $gte: myOffset } ).limit( myLimit ).sort( { mySortField : 1 } );
where myField, myOffset, myLimit and mySortField may be resolved from elsewhere at run-time.
This pattern is very useful to create such a run-time generated generic query.
Meteor seems to insist on the non-chained options pattern of
collection.find( { { myField: { $gte: myOffset } }, { limit: myLimit, sort: { mySortField : 1 }} );
and I am having problems 'building up' a working Find Query as required above from js objects as described
in previous questions 17362401 and 10959729
Would anyone like to help?
Edited to show usage of variable:
I do it this way. You send two hashes, where the first is the where clause, and all else are peer level keys.
var locations;
var myfield = 'gps';
search = {
sureties: {
$in: sureties
}
}
search[myfield] = {
$near: this.gps,
$maxDistance: kilometers
};
locations = Agents.find(search, {
fields: {
name: 1,
phone: 1
},
limit: limit,
sort: { field1 : 1 }
}).fetch();
The chained pattern is not possible in Meteor, neither server side nor on the client. But the params pattern is as universal, you should be able to create any query you need with those params.
Related
I just want to Publish the relational Data for a Publication to client, but the issue is my Relational Data field is array of ID's of a Different Collection, I tried Different Packages but all works with single Relational ID but not working with Array of relational ID's, let assume I have two Collection Companies and Meteor.users below is my Company Document Looks like
{
_id : "dYo4tqpZms9j8aG4C"
owner : "yjzakAgYWejmJcuHz"
name : "Labbaik Waters"
peoples : ["yjzakAgYWejmJcuHz", "yjzakAgYWejmJcuHz"],
createdAt: "2019-09-18T15:33:29.952+00:00"
}
here you can see peoples field contains the user ID's as Array, so How I publish this userId's as user Documents, as for example I tried the most popular meteor package named publishComposit, when I tried Loop in Children's find, I got undefined in children i.e below
publishComposite('compoundCompanies', {
find() {
// Find top ten highest scoring posts
return Companies.find({
owner: this.userId
}, {sort: {}});
},
children: [
{
find(company) {
let cursors = company.peoples.forEach(peopleId => {
console.log(peopleId)
return Meteor.users.find(
{ _id: peopleId },
{ fields: { profile: 1 } });
})
//here cursor undefined
console.log(cursors)
return cursors
}
}
]
});
and if I implement async loop in children's find I got error like below code
publishComposite('compoundCompanies', {
find() {
// Find top ten highest scoring posts
return Companies.find({
owner: this.userId
}, {sort: {}});
},
children: [
{
async find(company) {
let cursors = await company.peoples.forEach(peopleId => {
console.log(peopleId)
return Meteor.users.find(
{ _id: peopleId },
{ fields: { profile: 1 } });
})
//here cursor undefined
console.log(cursors)
return cursors
}
}
]
});
the error occured in above code is Exception in callback of async function: TypeError: this.cursor._getCollectionName is not a function
I don't know what I am exactly doing wrong here, or implementing package function not as intended any help will be greatly appropriated
EDIT: my desired result should be full user documents instead of ID no matter it mapped in same peoples array or as another fields I just want as below
{
_id: "dYo4tqpZms9j8aG4C",
owner: "yjzakAgYWejmJcuHz",
name: "Labbaik Waters",
peoples: [
{
profile: {firstName: "Abdul", lastName: "Hameed"},
_id: "yjzakAgYWejmJcuHz"
}
],
createdAt: "2019-09-18T15:33:29.952+00:00"
}
I ran into a similar problem couple of days ago. There are two problems with the provided code. First, using async; it's not needed and rather complicates things. Second, publishComposite relies on receiving one cursor not multiple within its children to work properly.
Below is a snippet of the code used to solve the problem I had, hopefully you can replicate it.
Meteor.publishComposite("table.conversations", function(table, ids, fields) {
if (!this.userId) {
return this.ready();
}
check(table, String);
check(ids, Array);
check(fields, Match.Optional(Object));
return {
find() {
return Conversation.find(
{
_id: {
$in: ids
}
},
{ fields }
);
},
children: [
{
find(conversation) {
// constructing one big cursor that entails all of the documents in one single go
// as publish composite cannot work with multiple cursors at once
return User.find(
{ _id: { $in: conversation.participants } },
{ fields: { profile: 1, roles: 1, emails: 1 } }
);
}
}
]
};
});
I have two collections A and B in Meteor. For A I have a publication where I filter out a range of documents in A. Now I want to create a publications for B where I publish all documents in B that have a field B.length matching A.length.
I have not been able to find any example where this is shown but I feel it must be a standard use case. How can this be done in Meteor?
This is a common pattern for reywood:publish-composite
import { publishComposite } from 'meteor/reywood:publish-composite';
publishComposite('parentChild', {
const query = ... // your filter
find() {
return A.find(query, { sort: { score: -1 }, limit: 10 });
},
children: [
{
find(a) {
return B.find({length: a.length });
}
}
]
});
This is a quite different pattern than serverTransform as on the client you end up with two collections, A and B, as opposed to a synthetic single collection A that has some fields of of B. The latter is more like a SQL JOIN.
Use serverTransform
Meteor.publishTransformed('pub', function() {
const filter = {};
return A.find(filter)
.serverTransform({
'B': function(doc) {
return B.find({
length: doc.length
}); //this will feed directly into miniMongo as if it was a seperate publication
}
})
});
With a structure of
/archive: {
$userId: {
$archiveKey: {
foo: 1
},
...
},
...
}
Where $userId references a user id and $archiveKey is dynamic, created by .push().
Is it possible to query the archive ref and get all archiveObjects where foo = 1 ? Or do I need to fetch down the whole table, manually dig into $userId and extract the archiveObjects I'm looking for?
Firebase queries can nowadays query nested paths, but the paths cannot be dynamic.
So if you know the uid, you can query that user's archives with:
ref.child(authData.uid).orderByChild('foo').equalTo(1).on(...
If you don't know the uid, then you'll have to create a data structure that allows you to do the lookup:
archive_category_to_uids: {
foo: {
1: {
uid1: true,
uid2: true
}
}
}
A more common way is to separate the archives into their own top-level list and have both users and categories refer to that:
users: {
userId1: {
archiveKey1: true,
...
},
...
},
archives: {
archiveKey1: {
foo: 1,
uid: uid1
},
...
},
archiveCategories: {
foo: {
1: {
archiveKey1: true,
archiveKey2: true
}
}
}
Now you can get find the archives with:
ref.child('archiveCategories/foo/1').once('value', function(keys) {
keys.forEach(function(key) {
ref.child('archives').child(key.key()).once('value', function(snapshot) {
console.log(snapshot.val());
});
};
});
This process is called denormalization and is quite common in NoSQL databases. You're modeling the data for how your application needs to consume it. For more on this and other common patterns, I recommend reading this article on NoSQL data modeling.
I’m having issues getting two dependant types of data from a PouchDB database.
I have a list of cars that I get like so:
localDB.query(function(doc) {
if (doc.type === ‘list’) {
emit(doc);
}
}, {include_docs : true}).then(function(response) {
console.log(“cars”, response);
// Save Cars List to app
for(var i = 0; i < response.rows.length; i++) {
addToCarsList(response.rows[i].id, response.rows[i].carNumber);
}
console.log(“Cars List: " + carsListToString());
return response;
}).then(function(listRecord) {
listRecord.rows.forEach(function(element, index){
console.log(index + ' -> ', element);
localDB.query(function(doc) {
console.log("filtering with carNb = " + element.carNb);
if (doc.type === 'defect' && doc.listId == getCurrentListId() && doc.carNb == element.carNb ) {
emit(doc);
}
}, {include_docs : false}).then(function(result){
console.log("defects", result);
}).catch(function(err){
console.log("an error has occurred", err);
});
});
}).catch(function(err) {
console.log('error', err);
});
Here's what happens. After getting the list of cars, then for each cars I would like to query the defects and store then in some arrays. Then when all that querying is done, I want to build the UI with the data saved.
But what's happening is that the forEach gets processed quickly and does not wait for the inner async'd localDb.query.
How can I query some documents based on an attribute from a parent query? I looked into promises in the PouchDB doc but I can't understand how to do it.
(please forget about curly quotes and possible lint errors, this code was anonymized by hand and ultra simplified)
The method you are looking for is Promise.all() (execute all promises and return when done).
However, your query is already pretty inefficient. It would be better to create a persistent index, otherwise it has to do a full database scan for every query() (!). You can read up on the PouchDB query guide for details.
I would recommend installing the pouchdb-upsert plugin and then doing:
// helper method
function createDesignDoc(name, mapFunction) {
var ddoc = {
_id: '_design/' + name,
views: {}
};
ddoc.views[name] = { map: mapFunction.toString() };
return ddoc;
}
localDB.putIfNotExists(createDesignDoc('my_index', function (doc) {
emit([doc.type, doc.listId, doc.carNb]);
})).then(function () {
// find all docs with type 'list'
return localDB.query('my_index', {
startkey: ['list'],
endkey: ['list', {}],
include_docs: true
});
}).then(function (response) {
console.log("cars", response);
// Save Cars List to app
for(var i = 0; i < response.rows.length; i++) {
addToCarsList(response.rows[i].id, response.rows[i].carNumber);
}
console.log("Cars List: " + carsListToString());
return response;
}).then(function (listRecord) {
return PouchDB.utils.Promise.all(listRecord.rows.map(function (row) {
// find all docs with the given type, listId, carNb
return localDB.query('my_index', {
key: ['defect', getCurrentListId(), row.doc.carNb],
include_docs: true
});
}));
}).then(function (finalResults) {
console.log(finalResults);
}).catch(function(err){
console.log("an error has occurred", err);
});
I'm using a few tricks here:
emit [doc.type, doc.listId, doc.carNb], which allows us to query by type or by type+listId+carNb.
when querying for just the type, we can do {startkey: ['list'], endkey: ['list', {}]}, which matches just those with the type "list" because {} is the "higher" than strings in CouchDB object collation order.
PouchDB.utils.Promise is a "hidden" API, but it's pretty safe to use if you ask me. It's unlikely we'll change it.
Edit Another option is to use the new pouchdb-find plugin, which offers a simplified query API designed to replace the existing map/reduce query() API.
Another approach would be to pull both the list docs and the defect docs down at the same time then merge them together using a reduce like method that will convert them into an array of objects:
{
_id: 1,
type: 'list',
...
defects: [{
type: 'defect'
listId: 1
...
}]
}
By pulling the list and the defects down in one call you save a several calls to the pouchdb query engine, but you do have to iterate through every result to build your collection of lists objects with and embedded array of defects.
// This is untested code so it may not work, but you should get the idea
var _ = require('underscore');
// order documents results by list then defect
var view = function (doc) {
if (doc.type === 'list') {
emit([doc._id, doc.carNumber, 1);
} else if (doc.type === 'defect') {
emit([doc.listId, doc.carNb, 2])
}
}
localDB.query(view, { include_docs: true })
.then(function(response) {
return _(response.rows)
.reduce(function(m, r) {
if (r.key[2] === 1) {
// initialize
r.doc.defects = [];
m.push(r.doc)
return m;
}
if (r.key[2] === 2) {
var list = _(m).last()
if (list._id === r.key[0] && list.carNumber === r.key[1]) {
list.defects.push(r.doc);
}
return m;
}
}, []);
})
.then(function(lists) {
// bind to UI
});
With couch, we found reducing calls to the couch engine to be more performant, but I don't know if this approach is better for PouchDB, but this should work as a solution, especially if you are wanting to embed several collections into one list document.
I'm using the following package in my project - https://github.com/matteodem/meteor-easy-search
Has anyone used it and was able to set custom mongo selectors for the query parameter? The leaderboard example isn't very clear to me. I need to be able to pass meteor user id to:
EasySearch.createSearchIndex('producers', {
'collection': Producers,
'field': ['name', 'producerIdNumber', 'blocksCount', 'totalHectares', 'totalArea'],
'limit': 8,
'use' : 'mongo-db',
'sort': function() {
return { 'created': -1, 'name': -1 };
},
'query': function() {
var selector = {};
return selector
}
});
How can pass or get the meteor user id? EasySearch.createSearchIndex function runs on both server and client.
I don't have the answer to your problem - but I may be able to point you in the right direction. If you are using the meteor-accounts package, and you need to pull the user ID out of the Meteor.users() collection - you first have to publish your users.
On the server-code ->
Meteor.publish(null, function() {
return Meteor.users.find({}, {
fields: {
username: 1,
profile: 1
}
});
});
on the client, you should be able to return Meteor.users.find() or findOne() to get a userId. not the complete answer but may help?
I was able to do this like so
'query': function(searchString, opts) {
// Default query that will be used for the mongo-db selector
var query = EasySearch.getSearcher(this.use).defaultQuery(this, searchString);
if (this.props.formName != '') {
query.formName = this.props.formName;
}
if (this.props.producerId != '') {
query.producerId = this.props.producerId;
}
if (this.props.blockUnitCodeSubCode != '') {
query.blockUnitCodeSubCode = this.props.blockUnitCodeSubCode;
}
if (this.props.created.length != 0) {
query.created = {$gte:new Date(this.props.created[0]), $lt:new Date(this.props.created[1])};
}