find by key is not working

[shaikhussian]

Hi,
Here is my response data

[{
	"confirmation": "Success",
	"response": [{
		"_id": "5a4f487089b4860014cddc51",
		"img1": "https://windows-price.s3.amazonaws.com/windows/1517418755884american-craftsman-double-hung-windows-3254786-64_1000.png",
		"name": "Double Hung (half-screen)",
		"__v": 0,
		"price": 900,
		"updated": "2018-01-05T09:42:08.170Z",
		"is_sash": false,
		"sash": [],
		"comments": "",
		"oriel": "false",
		"is_oriel": false,
		"dimension_size": 0,
		"is_speciality_selected": false,
		"is_speciality": false,
		"is_style": false,
		"is_grids": false,
		"styles": [],
		"dimension": [],
		"Tempered": "0",
		"Obscure": "0",
		"quantity": 0,
		"with_grid_price": 725,
		"with_out_grid_price": 675,
		"grids": [],
		"grid": "0",
		"max_ui": 136,
		"max_height": 84,
		"max_width": 52,
		"min_ui": 0,
		"min_height": 25.25,
		"min_width": 16
	}, {
		"_id": "5a4f491a89b4860014cddc52",
		"img1": "https://windows-price.s3.amazonaws.com/windows/1520980539939dbl-hung-oriel.png",
		"name": "Double Hung (Oriel Style) (half-screen)",
		"__v": 0,
		"price": 500,
		"updated": "2018-01-05T09:44:58.772Z",
		"is_sash": false,
		"sash": [],
		"comments": "top sash cannot exceed 50\"",
		"oriel": "false",
		"is_oriel": false,
		"dimension_size": 0,
		"is_speciality_selected": false,
		"is_speciality": false,
		"is_style": false,
		"is_grids": false,
		"styles": [],
		"dimension": [],
		"Tempered": "0",
		"Obscure": "0",
		"quantity": 0,
		"with_grid_price": 0,
		"with_out_grid_price": 0,
		"grids": [],
		"grid": "0",
		"max_ui": 136,
		"max_height": 84,
		"max_width": 52,
		"min_ui": 0,
		"min_height": 25.25,
		"min_width": 16
	}

i want use it search for that i used the command db.user.findById({"_id":"5a4f487089b4860014cddc51"}) but it is returning the response as null.

can any one give be suggestions that how can i done this.

Any suggestions much appreciated