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PODeserializing JSON
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  1. PODeserializing JSON
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    copied!<p>I'm trying to deserialize a relative simple JSON string, which looks like:</p> <pre><code>[{ "FacebookID": "00000000000000", "Items": [{ "BillID": "75a9ca7b-3b79-4db0-9867-83b2f66021d2", "FacebookID": "0000000000", "Description": "Some description", "Amount": 5000, "Accepted": false }] }, { "FacebookID": "00000000000000", "Items": [{ "BillID": "cec0a6d2-1db9-4a12-ae43-f61c6c69f0a6", "FacebookID": "0000000000", "Description": "Some description", "Amount": 3250, "Accepted": false }, { "BillID": "aaf51bb3-4ae6-48b5-aeb6-9c4d42fd4d2a", "FacebookID": "0000000000", "Description": "Some more..", "Amount": 100, "Accepted": false }] }, { "FacebookID": "0000000000", "Items": [{ "BillID": "2124cbc4-2a48-4ba4-a179-31d4191aab6a", "FacebookID": "0000000000", "Description": "even more..", "Amount": 300, "Accepted": false }] }] </code></pre> <p>nothing fancy as you see.. except for the <code>Items</code> array, but that shouldnt really be a problem.</p> <p>If we then make up a few types that matches the json-string, and a function that will deserialize the string and map it to the types we'll end up with something like:</p> <pre><code>[&lt;DataContract&gt;] type Item = { [&lt;field: DataMember(Name = "BillID")&gt;] BillID : string [&lt;field: DataMember(Name = "FacebookID")&gt;] FacebookID : string [&lt;field: DataMember(Name = "Description")&gt;] Description : string [&lt;field: DataMember(Name = "Amount")&gt;] Amount : int [&lt;field: DataMember(Name = "Accepted")&gt;] Accepted : bool } [&lt;DataContract&gt;] type Basic = { [&lt;field: DataMember(Name = "FacebookID")&gt;] FacebookID : string [&lt;field: DataMember(Name = "Items")&gt;] Items : Item array } // My function to deserialize the json string, and map it to the given type. let deserializeJson&lt;'a&gt; (s:string) = use ms = new MemoryStream(ASCIIEncoding.Default.GetBytes s) let serialize = DataContractSerializer(typeof&lt;'a&gt;) serialize.ReadObject ms :?&gt; 'a let get (url:string) = use web = new WebClient() web.DownloadString url // Returns the JSON string let result = deserializeJson&lt;Basic array&gt; &lt;| get "http://some.com/blabla" </code></pre> <p>Instead of doing its job, it simply throws following exception, when it's trying to deserialize the string:</p> <blockquote> <p>Unhandled Exception: System.Runtime.Serialization.SerializationException: There was an error deserializing the object of type System.Collections.Generic.IList`1 [[Program+Basic, ConsoleApplication1, Version=0.0.0.0, Culture=neutral, PublicKe yToken=null]]. The data at the root level is invalid. Line 1, position 1.</p> </blockquote> <p>Am I missing something? - The JSON-string is perfectly valid...</p>
 

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