fitness_goals.aggregate([
{'$match':{status:1,_id:{'$in':[ObjectId("5f606c24dedd8512595cbf37"),
ObjectId("5f9fadde6f738924c0b18e0a")]}}},
{'$unwind':'$recommendedRecipe'},
{'$group':{_id:null,recipeId:{'$addToSet':'$recommendedRecipe'}}},
Error in this Quoted section
{'$lookup':{from:'recipe_library',
let:{recipeId:'$recipeId'},pipeline:[{'$match':{'$expr':{'$and':[{'$in':['$_id','$$recipeId']},{status:1,recipeType:{'$ne':''}}]}}},
{'$limit':1}],as:'recipeData'}},
{'$project':{ recipeName: { '$arrayElemAt': [ '$recipeData.recipeName', 0 ] },}}
], {})
I was getting error while trying to put this in a formatted manner.
sampledoc
fitnessgoals:
{"_id":ObjectId("5f9fadde6f738924c0b18e0a"),"inCompatibleCategories":[],"recommendedWorkouts":[],"recommendedRecipe":[ObjectId("60085bcc1fb6ef515d49f824")],"noOfworkouts":[],"noOfrecipes":[],"status":1,"goalName":"Be Toned","createdAt":ISODate("2020-11-02T06:57:34.080Z"),"updatedAt":ISODate("2020-12-29T07:03:29.134Z"),"__v":0},
{"_id":ObjectId("5f606c24dedd8512595cbf37"),"goalName":"mental health","tags":"mental health","status":2,"inCompatibleCategories":[],"recommendedRecipe":[ObjectId("600876b8c645e7566434647a"),ObjectId("60085bcc1fb6ef515d49f824")],"recommendedWorkouts":[ObjectId("5f802424b6f11c2e85bc1473"),ObjectId("5f906681bbe83f3d4c75b279")],"updatedAt":ISODate("2020-11-02T06:59:13.827Z")}
RecipesDoc:
{"_id":ObjectId("600876b8c645e7566434647a"),"prepnTime":80,"totalTime":82,"cookingTime":2,"isRecomended":0,"noOfViews":0,"recipeType":'2',"noOfFavourite":0,"noOfTips":0,"noOfCompletion":0,"ratings1":0,"ratings2":0,"ratings3":0,"ratings4":0,"ratings5":0,"instructions":["recipe"],"categoryId":[ObjectId("5fead8c52422823bd0ee216f")],"tags":[],"nutritionServingSize":2,"ingredServingSize":1,"fitnessGoalsId":[ObjectId("5f9fadde6f738924c0b18e0a")],"dynamicPanel":"","status":2,"totalServing":1,"totalRatings":1,"ratedByCount":1,"avgRating":1,"totalCalories":0,"recipeCode":"recipe","recipeName":"recipe","recipeDesc":"recipe","adminId":ObjectId("5e0064311457694f9440f255"),"createdAt":ISODate("2021-01-20T18:30:16.384Z"),"updatedAt":ISODate("2021-01-20T19:10:16.396Z"),"__v":0},
{"_id":ObjectId("60085bcc1fb6ef515d49f824"),"prepnTime":0,"totalTime":10,"cookingTime":10,"isRecomended":0,"noOfViews":0,"recipeType":'1',"noOfFavourite":0,"noOfTips":0,"noOfCompletion":0,"ratings1":0,"ratings2":0,"ratings3":0,"ratings4":0,"ratings5":0,"nutritionServingSize":10,"ingredServingSize":2,"fitnessGoalsId":[ObjectId("5f606c24dedd8512595cbf37")],"dynamicPanel":"","status":2,"totalServing":1,"totalRatings":1,"ratedByCount":1,"avgRating":1,"totalCalories":0,"recipeCode":"hhfeuhfu","recipeName":"hdfdfhuhf","recipeDesc":"rfuhfuhrurhfu","adminId":ObjectId("5e0064311457694f9440f255"),"createdAt":ISODate("2021-01-20T16:35:24.347Z"),"updatedAt":ISODate("2021-01-20T16:36:00.981Z"),"__v":0}
question from:
https://stackoverflow.com/questions/65913744/mongoerror-expression-ne-takes-exactly-2-arguments-1-were-passed-in 
