Try the `$exists` operator:    

    db.mycollection.find({ &quot;price&quot; : { &quot;$exists&quot; : false } })

and see [its documentation](http://docs.mongodb.org/manual/reference/operator/query/exists/#op._S_exists).

I am having a problem where I am trying to delete my file but I get an exception.

    if (result == &quot;Success&quot;)
    {
         if (FileUpload.HasFile)
         {
             try
             {
                  File.Delete(Request.PhysicalApplicationPath + app_settings.login_images + txtUploadStatus.Text);
                  string filename = Path.GetFileName(btnFileUpload.FileName);
                  btnFileUpload.SaveAs(Request.PhysicalApplicationPath + app_settings.login_images + filename);
             }
             catch (Exception ex)
             {
                   Message(ex.ToString());
             }
          }
    }

Also I should note that the folder I am trying to delete from has full control to network services.

The full exception message is:

&gt;System.UnauthorizedAccessException: Access to the path &#39;C:\Users\gowdyn\Documents\Visual Studio 2008\Projects\hybrid\hybrid\temp_loginimages\enviromental.jpg&#39; is denied. at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) at System.IO.File.Delete(String path) at hybrid.User_Controls.Imgloader_Add_Edit_Tbl.btnUpdate_Click(Object sender, EventArgs e) in C:\Users\gowdyn\Documents\Visual Studio 2008\Projects\hybrid\hybrid\User_Controls\Imgloader_Add_Edit_Tbl.ascx.cs:line 242 

Any ideas?

Why is access to the path denied?

Is it possible: to have one field in class, but different names for it during serialization/deserialization in Jackson library?

For example, I have class &quot;Coordiantes&quot;.
    
    class Coordinates{
      int red;
    }

For deserialization from JSON want to have format like this:
    
    {
      &quot;red&quot;:12
    }

But when I will serialize object, result should be like this one:
   
    {
      &quot;r&quot;:12
    }

I tried to implement this by applying `@JsonProperty` annotation both on getter and setter (with different values):
    
    class Coordiantes{
        int red;
       
        @JsonProperty(&quot;r&quot;)
        public byte getRed() {
          return red;
        }

        @JsonProperty(&quot;red&quot;)
        public void setRed(byte red) {
          this.red = red;
        }
    }
but I got an exception:
     
&gt;org.codehaus.jackson.map.exc.UnrecognizedPropertyException: Unrecognized field &quot;red&quot;


Different names of JSON property during serialization and deserialization

Is there a way to specify a condition of &quot;where document doesn&#39;t contain field&quot; ?

For example, I want to only find the first of these 2 because it doesn&#39;t have the &quot;price&quot; field.

    {&quot;fruit&quot;:&quot;apple&quot;, &quot;color&quot;:&quot;red&quot;}


    {&quot;fruit&quot;:&quot;banana&quot;, &quot;color&quot;:&quot;yellow&quot;, &quot;price&quot;:&quot;2.00&quot;}



MongoDB: Find a document by non-existence of a field?

Is there a way to specify a condition of "where document doesn't contain field" ?
For example, I want to only find the first of these 2 because it doesn't have the "price" field.
<pre><code class="hljs language-json">{"fruit":"apple", "color":"red"}


{"fruit":"banana", "color":"yellow", "price":"2.00"}
</code></pre>

I&#39;m learning about map-reduce functionality of mongodb. My first tests doesn&#39;t work as I expected and I want to know how is it working.

Is there **any way to write to mongodb console from javascript functions** so I can inspect it?

I tried `console.log(&quot;...&quot;)` but it doesn&#39;t work.

I will ask later about my tests if there isn&#39;t any way to do it.


Is it possible to write to mongodb console in javascript execution?

This is my folder structure:

    +-- express_example
    |---- app.js
    |---- models
    |-------- songs.js
    |-------- albums.js
    |---- and another files of expressjs

My code in file songs.js 

    var mongoose = require(&#39;mongoose&#39;)
    , Schema = mongoose.Schema
    , ObjectId = Schema.ObjectId;

    var SongSchema = new Schema({
	name: {type: String, default: &#39;songname&#39;}
	, link: {type: String, default: &#39;./data/train.mp3&#39;}
	, date: {type: Date, default: Date.now()}
	, position: {type: Number, default: 0}
	, weekOnChart: {type: Number, default: 0}
	, listend: {type: Number, default: 0}
    });

    module.exports = mongoose.model(&#39;Song&#39;, SongSchema);


And here is my code in file albums.js

    var mongoose = require(&#39;mongoose&#39;)
    , Schema = mongoose.Schema
    , ObjectId = Schema.ObjectId;

    var AlbumSchema = new Schema({
	name: {type: String, default: &#39;songname&#39;}
	, thumbnail: {type:String, default: &#39;./images/U1.jpg&#39;}
	, date: {type: Date, default: Date.now()}
	, songs: [SongSchema]
    });

    module.exports = mongoose.model(&#39;Album&#39;, AlbumSchema);

&lt;br/&gt; How can I make albums.js know &lt;strong&gt;SongSchema&lt;/strong&gt; to be defined AlbumSchema

How to get Schema of mongoose database which defined in another model

Is there a dead easy way to rename a collection in mongo?  Something like:

    db.originalCollectionName.rename(&#39;newCollectionName&#39;);

And if not, what is the best way to go about effectively renaming one?

How can I rename a collection in MongoDB?

I know that ObjectIds contain the date they were created on. Is there a way to query this aspect of the ObjectId?


Can I query MongoDB ObjectId by date?

I&#39;m doing a simple insert into Mongo...

    db.notes.insert({ title: &quot;title&quot;, details: &quot;note details&quot;})


After the note document is inserted, I need to get the object id immediately. The result that comes back from the insert has some basic info regarding connection and errors, but no document and field info.

I found some info about using the update() function with upsert=true, I&#39;m just not sure if that&#39;s the right way to go, I have not yet tried it. 




Content Type	Original Author	Original Content on Stackoverflow
Question	k00k	View Question on Stackoverflow
Solution 1 - Mongodb	dampier	View Answer on Stackoverflow

MongoDB: Find a document by non-existence of a field?

Mongodb Problem Overview

Mongodb Solutions

Solution 1 - Mongodb

Different names of JSON property during serialization and deserialization

Why is access to the path denied?

Attributions