This library is usefull example with expressjs + mongoose applications to help construct mongoose query model directly from url parameters. Example:

http://localhost/model?q={"group":"users"}&f=name&sk=1&l=5&p=name

Converted to:

model.find({group: "users"}).select("name").skip(1).limit(5).populate('name')

12.x, 14.x, 16.x,latest release

See releases page.

Use npm:

npm install mongoose-query

npm test && npm run lint

var QueryPlugin = require(mongoose-query);
var TestSchema = new mongoose.Schema({});
TestSchema.plugin(QueryPlugin);
var testmodel = mongoose.model('test', TestSchema);

//express route
module.exports = function query(req, res) {
  testmodel.query(req.query, function(error, data){
    res.json(error?{error: error}:data);
  });
}

var QueryPlugin = require(mongoose-query);
schema.plugin( QueryPlugin(, <options>) )

optional options:

• logger: custom logger, e.g. winston logger, default: "dummy logger"
• includeAllParams: Parse also other values. e.g. ?name=me. default: true
• ignoreKeys : <array{String}> keys to be ignored. Default: []

Model static methods:

model.query( <query>(, <callback>) )

model.leanQuery(<query>(, <callback>) ): gives plain objects (lean)

Note: without <callback> you get Promise.

URL API:

http://www.myserver.com/query?[q=<query>][&t=<type>][&f=<fields>][&s=<order>][&sk=<skip>]
[&l=<limit>][&p=<populate>][&fl=<boolean>][&map=<mapFunction>][&reduce=<reduceFunction>]

q=<query>                   restrict results by the specified JSON query
                            regex e.g. q='{"field":{"$regex":"/mygrep/", "$options":"i"}}'
t=<type>                    find|findOne|count|estimateCount|aggregate|distinct|aggregate|mapReduce
f=<set of fields>           specify the set of fields to include or exclude in each document
                            (1 - include; 0 - exclude)
s=<sort order>              specify the order in which to sort each specified field
                            (1- ascending; -1 - descending), JSON
sk=<num results to skip>    specify the number of results to skip in the result set;
                            useful for paging
l=<limit>                   specify the limit for the number of results (default is 1000)
p=<populate>                specify the fields for populate, also more complex json object is supported.
x=<explain>                 allowed values: 'queryPlanner', 'executionStats', 'allPlansExecution'
to=<ms>                     timeout for query
d=<boolean>                 allowDiskUse (for heavy queries)
map=<mapFunction>           mongodb map function as string
                            http://docs.mongodb.org/manual/reference/command/mapReduce/#mapreduce-map-cmd'
                            e.g. "function(){if (this.status == 'A') emit(this.cust_id, 1);)}"
reduce=<reduceFunction>     mongodb reduce function as string
                            http://docs.mongodb.org/manual/reference/command/mapReduce/#mapreduce-reduce-cmd
                            e.g. "function(key, values) {return result;}"
fl=<boolean>                Flat results or not

Special values:
"oid:<string>"              string is converted to ObjectId
"/regex/(options)"          converted to regex
{ $regex: /<string>/,       regex match with optional regex options
 ($options: "") }        

Alternative search conditions:
"key={i}a"                  case insensitive
"key={e}a"                  ends with a
"key={ei}a"                 ends with a, case insensitive
"key={b}a"                  begins with a
"key={bi}a"                 begins with a, case insensitive
"key={in}a,b"               At least one of these is in array
"key={nin}a,b"              Any of these values is not in array
"key={all}a,b"              All of these contains in array
"key={empty}"               Field is empty or not exists
"key={!empty}"              Field exists and is not empty
"key={mod}a,b"              Docs where key mod a is b
"key={gt}a"                 value is greater than a
"key={gte}a"                value is greater or equal than a
"key={lt}a"                 value is lower than a
"key={lte}a"                value is lower or equal
"key={ne}a"                 value is not equal
"key={size}a"               value is array, and array size is a
"key={sort_by}"             sort by asc
"key={sort_by}-1"           sort by desc

**References to mongo:**
- [elemMatch](https://docs.mongodb.com/manual/reference/operator/query/elemMatch/)
- [size](https://docs.mongodb.com/manual/reference/operator/query/size/)

Results with fl=false:

[
 {
 	nest: {
    ed: {
      data: 'value',
      data2':'value'
    }
  }
}
]

Results with fl=true:

[
 {'nest.ed.data': 'value',
  'nest.ed.data2':'value'},
]

Allowed date formats:

• 2010/10/1 (y/m/d)
• 31/2/2010 (d/m/y)
• 2011-10-10T14:48:00 (ISO 8601)

Note: Only valid format is ISO when using date inside q -parameter.