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POfindOne use in mapreduce mongodb
 

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    <p>I want to use <code>findOne</code> in map reduce. What is wrong with my code? My error is:</p> <p>Command 'mapreduce' failed: exception: map invoke failed: JS Error: TypeError: user has no properties nofile_b:3 (response: { "errmsg" : "exception: map invoke failed: JS Error: TypeError: user has no properties nofile_b:3", "code" : 9014, "ok" : 0.0 })</p> <pre><code>string map = @" function() { var movie = this; var user = db.users.findOne({UserId : parseInt(movie.UserId)}); emit( movie.UserId, {Name:user.Name}); }"; string reduce = @" function(key, values) { var result =values; return result; }"; string finalize = @" function(key, value){ return value; }"; </code></pre> <p>Under c# code</p> <pre><code>var collection = database.GetCollection("movies"); var options = new MapReduceOptionsBuilder(); options.SetFinalize(finalize); options.SetOutput(MapReduceOutput.Inline); var results = collection.MapReduce(map, reduce, options); lbResultList.Items.Clear(); foreach (var result in results.GetResults()) { lbResultList.Items.Add(result.ToJson()); } </code></pre> <p>I solve my problem map function change </p> <pre><code>function () { var user = db.users.find({UserId:this.UserId}); var userName =''; var userSurName =''; user.forEach(function(u) { userName = u.Name; userSurName = u.SurName; }); emit( this._id, {title: this.Title,category:this.Category,UserName: userName,UserSurName: userSurName} ); </code></pre> <p>}</p> <p>I think it is not logical,like sub query this solve. What can I do this case?</p>
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    1. USnercan
    1. USnercan
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    1. COYou are not permitted to use the db object from MR. I am unsure how you even came by this code since all information mentioned on MongoDBs site of using the db object in MR was taken out in like version 1.6 if not earlier
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      1. USSammaye
    2. COYou've created two collections - that means you will need to always do two queries to "join" their output. If that's unacceptable you might consider changing your schema to accommodate the requirement to fetch information about users and movies in a single collection operation.
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      1. POfindOne use in mapreduce mongodb
      1. USAsya Kamsky
 

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