Missing Note: EF Core Cosmos provider does not support collections of primitive types

[seangwright]

Currently there is a feature missing from the EF Core Cosmos provider - it cannot handle collections of primitive types on entities.

This is something that Cosmos (and all other document storage systems) support natively. It is the EF Core provider which prevents a developer from using this normal functionality.

I just spent an hour searching the (very very limited) EF Core Cosmos provider docs, blogs, the EF Core repo, ect... trying to figure out what was causing this exception:

'The property [...] could not be mapped because it is of type 'ICollection', which is not a supported primitive type or a valid entity type. Either explicitly map this property, or ignore it using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.'

Whether or not the provider supports this functionality isn't what I'm concerned about (though, this seems like a big feature gap), but it should be mentioned somewhere in the EF Core Cosmos provider docs that this is a current limitation, along with the exception message to help developers figure out why this doesn't work.

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Document Details

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• ID: 738deb7b-d752-f628-3860-fe53891cadb0
• Version Independent ID: e0a18db9-d605-2a78-b77a-d22375dcfd4e
• Content: Azure Cosmos DB Provider - EF Core
• Content Source: entity-framework/core/providers/cosmos/index.md
• Product: entity-framework
• Technology: entity-framework-core
• GitHub Login: @AndriySvyryd
• Microsoft Alias: avickers

[unt1tled]

Just ran into this issue as well while following MS's own recommendations on modeling and partitioning. Having to create separate complex objects just for this bloats our scheme here.