How to apply fields filter on nested object in loopback model query?

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I have this data on mongodb in a table named "Alerts" in geojson format


 "_id" : ObjectId("5be40b8099d5b81e6115d517"),
"title" : "Real-time earthquake",
"priority" : "high",
"status" : NumberInt("1"), 
"extAlertData" : 
 "type" : "Feature",
 "properties" : 
 "mag" : 4.11,
 "place" : "12km S of Tres Pinos, CA",
 "time" : 1541163534230,
 ,
 "geometry" : 
 "type" : "Point",
 "coordinates" : [
 -121.3146667,
 36.6801667,
 6.48
 ]
 ,
 "id" : "nc73105276"
 


"_id" : ObjectId("5be401c39b9e021a4c1a5c80"),
"title" : "Real-time earthquake",
"priority" : "high",
"status" : NumberInt("1"), 
"extAlertData" : 
 "type" : "Feature",
 "properties" : 
 "mag" : 4.5,
 "place" : "107km NW of Tobelo, 
 Indonesia",
 "time" : 1541665816710,
 ,
 "geometry" : 
 "type" : "Point",
 "coordinates" : [
 127.2763,
 2.3671,
 31.55
 ]
 ,
 "id" : "us1000hp6t"

I want to retrieve the field "id" which is nested inside "extAlertData" using model query.

Following query does not working.

db.Alerts.find(fields : "extAlertData.id": true,
 function (err, Alerts)
 //process alert extAlertData.id
 
});

Query is retrieving the following error:

TypeError: Cannot read property 'id' of undefined

How can I query using fields filter in mongoDB? I am using loopback framework of node js.

Thanks in advance.

edited Nov 9 at 5:14

asked Nov 8 at 12:50

Annie

113

New contributor

1

You need to use $exists if you are looking to check the existence of 'id' filed db.Alerts.find( 'extAlertData.id': $exists: true). And i guess the part 'fields : ' i wrong in your query
– Avij
Nov 8 at 13:41

Sorry. I am not looking for existence of 'id' field in db. I have array of similar object in the given format as specified in the question.I am trying to get all "extAlertData.id" and save to an array.
– Annie
Nov 8 at 13:59

Then you need to check if it exists in the record and then project it
– Avij
Nov 8 at 14:02

can you please help me with the query? How to specify to get all "extAlertData.id"
– Annie
Nov 8 at 14:06

1

@AnthonyWinzlet . It's working.I got the expected output.Thank you so much
– Annie
Nov 9 at 5:38

);

Query is retrieving the following error:

TypeError: Cannot read property 'id' of undefined

How can I query using fields filter in mongoDB? I am using loopback framework of node js.

Thanks in advance.

edited Nov 9 at 5:14

asked Nov 8 at 12:50

Annie

113

New contributor

1

You need to use $exists if you are looking to check the existence of 'id' filed db.Alerts.find( 'extAlertData.id': $exists: true). And i guess the part 'fields : ' i wrong in your query
– Avij
Nov 8 at 13:41

Sorry. I am not looking for existence of 'id' field in db. I have array of similar object in the given format as specified in the question.I am trying to get all "extAlertData.id" and save to an array.
– Annie
Nov 8 at 13:59

Then you need to check if it exists in the record and then project it
– Avij
Nov 8 at 14:02

can you please help me with the query? How to specify to get all "extAlertData.id"
– Annie
Nov 8 at 14:06

1

@AnthonyWinzlet . It's working.I got the expected output.Thank you so much
– Annie
Nov 9 at 5:38

);

Query is retrieving the following error:

TypeError: Cannot read property 'id' of undefined

How can I query using fields filter in mongoDB? I am using loopback framework of node js.

Thanks in advance.

edited Nov 9 at 5:14

asked Nov 8 at 12:50

Annie

113

New contributor

I have this data on mongodb in a table named "Alerts" in geojson format


 "_id" : ObjectId("5be40b8099d5b81e6115d517"),
"title" : "Real-time earthquake",
"priority" : "high",
"status" : NumberInt("1"), 
"extAlertData" : 
 "type" : "Feature",
 "properties" : 
 "mag" : 4.11,
 "place" : "12km S of Tres Pinos, CA",
 "time" : 1541163534230,
 ,
 "geometry" : 
 "type" : "Point",
 "coordinates" : [
 -121.3146667,
 36.6801667,
 6.48
 ]
 ,
 "id" : "nc73105276"
 


"_id" : ObjectId("5be401c39b9e021a4c1a5c80"),
"title" : "Real-time earthquake",
"priority" : "high",
"status" : NumberInt("1"), 
"extAlertData" : 
 "type" : "Feature",
 "properties" : 
 "mag" : 4.5,
 "place" : "107km NW of Tobelo, 
 Indonesia",
 "time" : 1541665816710,
 ,
 "geometry" : 
 "type" : "Point",
 "coordinates" : [
 127.2763,
 2.3671,
 31.55
 ]
 ,
 "id" : "us1000hp6t"

I want to retrieve the field "id" which is nested inside "extAlertData" using model query.

Following query does not working.

db.Alerts.find(fields : "extAlertData.id": true,
 function (err, Alerts)
 //process alert extAlertData.id
 
});

Query is retrieving the following error:

TypeError: Cannot read property 'id' of undefined

How can I query using fields filter in mongoDB? I am using loopback framework of node js.

Thanks in advance.

node.js mongodb mongodb-query loopback

edited Nov 9 at 5:14

asked Nov 8 at 12:50

Annie

113

New contributor

edited Nov 9 at 5:14

asked Nov 8 at 12:50

Annie

113

New contributor

edited Nov 9 at 5:14

asked Nov 8 at 12:50

Annie

113

New contributor

asked Nov 8 at 12:50

Annie

113

asked Nov 8 at 12:50

Annie

113

New contributor

Annie is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

1

You need to use $exists if you are looking to check the existence of 'id' filed db.Alerts.find( 'extAlertData.id': $exists: true). And i guess the part '{fields : ' i wrong in your query
– Avij
Nov 8 at 13:41

Sorry. I am not looking for existence of 'id' field in db. I have array of similar object in the given format as specified in the question.I am trying to get all "extAlertData.id" and save to an array.
– Annie
Nov 8 at 13:59

Then you need to check if it exists in the record and then project it
– Avij
Nov 8 at 14:02

can you please help me with the query? How to specify to get all "extAlertData.id"
– Annie
Nov 8 at 14:06

1

@AnthonyWinzlet . It's working.I got the expected output.Thank you so much
– Annie
Nov 9 at 5:38

|
show 6 more comments

1

You need to use $exists if you are looking to check the existence of 'id' filed db.Alerts.find( 'extAlertData.id': $exists: true). And i guess the part '{fields : ' i wrong in your query
– Avij
Nov 8 at 13:41

Sorry. I am not looking for existence of 'id' field in db. I have array of similar object in the given format as specified in the question.I am trying to get all "extAlertData.id" and save to an array.
– Annie
Nov 8 at 13:59

Then you need to check if it exists in the record and then project it
– Avij
Nov 8 at 14:02

can you please help me with the query? How to specify to get all "extAlertData.id"
– Annie
Nov 8 at 14:06

1

@AnthonyWinzlet . It's working.I got the expected output.Thank you so much
– Annie
Nov 9 at 5:38

You need to use $exists if you are looking to check the existence of 'id' filed db.Alerts.find( 'extAlertData.id': $exists: true). And i guess the part '{fields : ' i wrong in your query
– Avij
Nov 8 at 13:41

Sorry. I am not looking for existence of 'id' field in db. I have array of similar object in the given format as specified in the question.I am trying to get all "extAlertData.id" and save to an array.
– Annie
Nov 8 at 13:59

Then you need to check if it exists in the record and then project it
– Avij
Nov 8 at 14:02

can you please help me with the query? How to specify to get all "extAlertData.id"
– Annie
Nov 8 at 14:06

@AnthonyWinzlet . It's working.I got the expected output.Thank you so much
– Annie
Nov 9 at 5:38

|
show 6 more comments

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