mongo-aggregation-debugger
v1.0.4
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Node.js MongoDB aggregation framework debugger methods
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Mongo Aggregation Debugger
Mongo Aggregation Debugger helps debug MongoDb aggregation queries by being able to visualize each stage of the pipeline
Why use it
It is pretty hard to understand why a specific aggregation query fails or doesn't output the right results since it can be pretty complex and go through a lot of stages before returning values.
The Mongo Aggregation Debugger helps you understand what is going on by either:
- outputting in the console the results of each stage of the aggregation pipeline
- returning an array of results of each stage of teh aggregation pipeline for programmatic use
- running the query in a temporary database and outputting the results, very useful for automated testing
How it works
You give the debugger access to your instance of mongodb, and it creates a temporary collection in which it will run each stage of the aggregation query in series. The temporary database is dropped after each debug.
Install
npm install mongo-aggregation-debugger
Instantiation
var mad = require('mongo-aggregation-debugger')();
You can provide an optional object as an argument to specify the mongodb connection information:
key | default value | description
------------ | ------------- | -------------
host | localhost
| mongodb host name
port | 27017
| mongodb port number
username | null
| (optional) username of the mongodb instance
password | null
| (optional) password of the mongodb instance
options | {}
| (optional) additional mongodb options
API
log
This method outputs in the console the result of each stage of the aggregation pipeline.
Use
log(data, query[, options][, callback])
argument | type | values | description
------------ | ------------- | ------------- | -------------
data | array
| | The data to run the query against
query | array
| | The aggregation query
options | object
| showQuery
: boolean
| Whether to show the query of the stage being run or not
callback | function(err)
| | The callback returned when all stages were executed
Example:
var mad = require('mongo-aggregation-debugger')();
var data = [{
foo: 'bar',
test: true,
array: [ 1, 2, 3 ]
}, {
foo: 'bar2',
test: false,
array: [ 10, 20 ]
}];
var query = [{
'$match': {
test: true
}
}, {
'$project': {
foo: 1,
array: 1
}
}, {
'$unwind': "$array"
}, {
'$group': {
_id: "$foo",
foo: { $first: "$foo" },
sum: { $sum: "$array" }
}
}];
mad.log(data, query, function (err) {
if (err) {
// do something
}
console.log('All done!');
});
Running the code above would output this in your console:
Example with the showQuery
option:
mad.log(data, query, { showQuery: true }, function (err) {
if (err) {
// do something
}
console.log('All done!');
});
stages
This method returns the result of each stage of the aggregation pipeline for programmatic use.
Use
stages(data, query[, callback])
argument | type | description
------------ | ------------- | ------------- | -------------
data | array
| The data to run the query against
query | array
| The aggregation query
callback | function(err, results)
| results
is an array composed of as many objects as there are stages in the aggregation pipeline. Each object has a query
attribute which is the query of the stage and a result
attribute with the results of that query
Example:
var util = require('util');
var mad = require('mongo-aggregation-debugger')();
var data = [{
foo: 'bar',
test: true,
array: [ 1, 2, 3 ]
}, {
foo: 'bar2',
test: false,
array: [ 10, 20 ]
}];
var query = [{
'$match': {
test: true
}
}, {
'$project': {
foo: 1,
array: 1
}
}, {
'$unwind': "$array"
}, {
'$group': {
_id: "$foo",
foo: { $first: "$foo" },
sum: { $sum: "$array" }
}
}];
mad.stages(data, query, function (err, results) {
if (err) {
// do something
}
console.log(util.inspect(results, { depth: null }));
});
The output is:
[ { query: [ { '$match': { test: true } } ],
results:
[ { _id: 5599279a731b5aba47df6d97,
foo: 'bar',
test: true,
array: [ 1, 2, 3 ] } ] },
{ query:
[ { '$match': { test: true } },
{ '$project': { foo: 1, array: 1 } } ],
results: [ { _id: 5599279a731b5aba47df6d97, foo: 'bar', array: [ 1, 2, 3 ] } ] },
{ query:
[ { '$match': { test: true } },
{ '$project': { foo: 1, array: 1 } },
{ '$unwind': '$array' } ],
results:
[ { _id: 5599279a731b5aba47df6d97, foo: 'bar', array: 1 },
{ _id: 5599279a731b5aba47df6d97, foo: 'bar', array: 2 },
{ _id: 5599279a731b5aba47df6d97, foo: 'bar', array: 3 } ] },
{ query:
[ { '$match': { test: true } },
{ '$project': { foo: 1, array: 1 } },
{ '$unwind': '$array' },
{ '$group':
{ _id: '$foo',
foo: { '$first': '$foo' },
sum: { '$sum': '$array' } } } ],
results: [ { _id: 'bar', foo: 'bar', sum: 6 } ] } ]
exec
This method only runs the entire query passed, not all the stages seperately. It is useful for automated tests since it creates and drops a temporary database.
Use
exec(data, query[, callback])
argument | type | description
------------ | ------------- | ------------- | -------------
data | array
| The data to run the query against
query | array
| The aggregation query
callback | function(err, results)
| results
is the results of the query being run
Example:
var util = require('util');
var mad = require('mongo-aggregation-debugger')();
var data = [{
foo: 'bar',
test: true,
array: [ 1, 2, 3 ]
}, {
foo: 'bar2',
test: false,
array: [ 10, 20 ]
}];
var query = [{
'$match': {
test: true
}
}, {
'$project': {
foo: 1,
array: 1
}
}, {
'$unwind': "$array"
}, {
'$group': {
_id: "$foo",
foo: { $first: "$foo" },
sum: { $sum: "$array" }
}
}];
mad.exec(data, query, function (err, results) {
if (err) {
// do something
}
console.log(util.inspect(results, { depth: null }));
});
The output is:
[ { _id: 'bar', foo: 'bar', sum: 6 } ]
Unit tests
In order to test this lib you'll need to install mocha: npm install -g mocha
.
Then just run the mocha
command at the root of the project.
More info
Contribute
If you think it would make sense to add some features/methods don't hesitate to fork and make pull requests.
You can contact the main contributor on Twitter
Licence
Distributed under the MIT License.