I am using Cosmosdb with .net CORE 2.2 and the Cosmosdb SQL SDK. By default cosmosdb will assign every documents 'Id' property as a Guid. But the Id alone is not enough to directly read the document, you must also know its partition. So I created a class named CosmosGuid that contains a Id property(Guid) and a PartitionKey property(string). The ToString() is overridden to call .ToString("N") on the Guid to remove the dashes and it appends the PartitionKey to the end. The problem im having is when I use the CosmosGuid in Linq, the generated SQL will contain a json version of CosmosGuid, I really need it to just be a string. I can call .ToString() and that will produce the desired result, but im afraid another developer will use my class in a Linq expression and it fail for no known reason. When I save the CosmosGuid I created a custom newtonsoft converter to call ToString() when it saves and to call .Parse(string) when it reads. When you compare two Guids in Linq the generated SQL comes out to a string, but when I compare two CosmosGuid it creates a json string of my class. How can I make my class act like a Guid?
I have already attempted to implement all the same Interfaces as the Guid. The closes I have came was implementing 'IEnumerable' and in the GetComparer() I returned:
new string[] { this.ToString() }.GetEnumerator();
The code produced was perfect, but it kept putting my string surrounded with brackets[].
here is an example:
SELECT VALUE root FROM root WHERE (root['id'] = ['9a9dbbd5f78143c48b16f780c7ceaa4011'])
This is the CosmosGuid class, I figure id post the full class since its not very large and it may be useful to some.
public class CosmosGuid
{
// This is the unique Id of the entity
public Guid Guid { get; set; }
// This is the partition key where the entity lives
public string PartitionKey { get; set; }
// This is the unique Id of the Document that contains the entity
public Guid? ParentGuid { get; set; }
// This is the PartitionKey of the Document that contains the entity
public string ParentPartitionKey { get; set; }
/// <summary>
/// Parses a CosmosGuid string into a new CosmosGuid
/// </summary>
/// <param name="cosmosGuid"></param>
public CosmosGuid(string cosmosGuid)
{
ParentGuid = null;
ParentPartitionKey = null;
try
{
var parsed = cosmosGuid.Split('-');
// We can accuratly parse the guid from the string by always grabing the first 32 characters.
// The characters after the first 32 are the PartitionKey.
// https://stackoverflow.com/a/4458925
// Guid.NewGuid().ToString("N") => 32 characters (digits only, no dashes)
Guid = Guid.Parse(parsed[0].Substring(0, 32));
PartitionKey = parsed[0].Substring(32, parsed[0].Length - 32);
if (parsed.Length == 2)
{
ParentGuid = Guid.Parse(parsed[1].Substring(0, 32));
ParentPartitionKey = parsed[1].Substring(32, parsed[1].Length - 32);
}
}
catch (Exception ex)
{
throw new Exception("The Id of the document is not a properly formatted CosmosGuid.", ex);
}
}
/// <summary>
/// Generates a new Guid and appends the PartitionKey. This is used for Documents.
/// </summary>
/// <param name="partitionKey"></param>
/// <returns></returns>
public static CosmosGuid NewCosmosGuid(string partitionKey)
{
return new CosmosGuid($"{ShortenGuid(Guid.NewGuid())}{partitionKey}");
}
/// <summary>
/// Generates a new Guid and appends the PartitionKey as well as the Parent Guid and Parent PartitionKey. This is used for Subdocuments.
/// </summary>
/// <param name="parent"></param>
/// <param name="partitionKey"></param>
/// <returns></returns>
public static CosmosGuid NewCosmosGuid(CosmosGuid parent, string partitionKey)
{
return new CosmosGuid($"{ShortenGuid(Guid.NewGuid())}{partitionKey}-{ShortenGuid(parent.Guid)}{parent.PartitionKey}");
}
/// <summary>
/// Returns only the Parent CosmosGuid. If there is no parent the value returned will be null.
/// </summary>
public CosmosGuid Parent
{
get
{
if (ParentGuid != null && ParentPartitionKey != null)
return new CosmosGuid($"{ShortenGuid((Guid)ParentGuid)}{ParentPartitionKey}");
else
return null;
}
}
/// <summary>
/// Parses a CosmosGuid string into a new CosmosGuid.
/// </summary>
/// <param name="cosmosGuid"></param>
/// <returns></returns>
public static CosmosGuid Parse(string cosmosGuid)
{
return new CosmosGuid(cosmosGuid);
}
/// <summary>
/// Generates a CosmosGuid formatted string.
/// </summary>
/// <returns></returns>
public override string ToString()
{
if (ParentGuid == null)
return $"{ShortenGuid(Guid)}{PartitionKey}";
else
return $"{ShortenGuid(Guid)}{PartitionKey}-{ShortenGuid((Guid)ParentGuid)}{ParentPartitionKey}";
}
/// <summary>
/// Removes the dashes from a Guid
/// </summary>
/// <param name="guid"></param>
/// <returns></returns>
private static string ShortenGuid(Guid guid)
{
// Just remove dashes from the guid to shorten it some.
// More can be done here if you wish but make sure the guid uniqueness isnt compromised.
return guid.ToString("N");
}
public static bool operator ==(CosmosGuid obj1, CosmosGuid obj2)
{
return obj1?.ToString() == obj2?.ToString();
}
public static bool operator !=(CosmosGuid obj1, CosmosGuid obj2)
{
return obj1?.ToString() != obj2?.ToString();
}
}
If a developer where to use the CosmosGuid like so it would fail to work, because the SQL generated is a Json version of the class. (the Id is also a CosmosGuid):
var cosmosGuid = CosmosGuid.Parse("6bec688a0aca477c8175c09162b7a9b411");
var result = await Client.CreateDocumentQuery<MyClass>(UriFactory.CreateDocumentCollectionUri(DatabaseId, CollectionId), options)
.Where(x => x.Id == cosmosGuid)
.AsDocumentQuery();
This is the sql generated
SELECT VALUE root FROM root WHERE (root['id'] = {'Guid':'6bec688a-0aca-477c-8175-c09162b7a9b4','PartitionKey':'11','ParentGuid':null,'ParentPartitionKey':null,'Parent':null})
Instead, the developer must call .ToString() everywhere in the code.
var cosmosGuid = CosmosGuid.Parse("6bec688a0aca477c8175c09162b7a9b411");
var result = await Client.CreateDocumentQuery<MyClass>(UriFactory.CreateDocumentCollectionUri(DatabaseId, CollectionId), options)
.Where(x => x.Id.ToString() == cosmosGuid.ToString())
.AsDocumentQuery();
This is the Sql generated
SELECT VALUE root FROM root WHERE (root['id'] = '6bec688a0aca477c8175c09162b7a9b411')
If I remove the CosmosGuid and revert back to using just a Guid as the Id property the SQL generated by the Cosmosdb SDK works fine. How can I make my class act like a .net Guid when used in Linq?
