CODEWITHSUNDEEP
javascriptbreezehottowel
user918064
user918064

Reputation: 145

The 'entityType' parameter must be an instance of 'EntityType'

I'm just starting out with BreezeJS and using the HotTowel template with Asp.Net Web Api and EF

I've got to the point of trying to retrieve a record using manager.getEntityByKey, using the example at http://www.breezejs.com/documentation/querying-locally

To test I'm using the code:

 var key = new breeze.EntityKey("LibraryItemCategory", 1);
            var entity = manager.getEntityByKey(key);

But when the code is called I get the error 'The 'entityType' parameter must be an instance of 'EntityType' ' for the first line of code.

At the point the code is called the manager has the "LibraryItemCategory" entities loaded, and I have used Visual Studio to confirm the entityType shortName is "LibraryItemCategory"

Can anyone suggest what is wrong in the code or how I can get past this?

Thanks

Mark

Upvotes: 0

Views: 1058

Answers (2)

user918064
user918064

Reputation: 145

Finally figured it out, I had forgotten to 'Prime' the app by calling Metadata from the server so Breeze didn't understand what the type was

Upvotes: 0

Ward
Ward

Reputation: 17863

The problem is that the EntityKey constructor's first parameter must be an instance of EntityType, not the name of the type. See the API doc.

Therefore, you'd do something like this

var type = manager.metadataStore.getEntityType("LibraryItemCategory");
var key = new breeze.EntityKey(type, 1);
var entity = manager.getEntityByKey(key);

A bit clunky.

You might wonder Why doesn't EntityKey accept the name of the type and use that to find the EntityType?

Well ... it can't ... because the EntityKey "class" has no way to discover your EntityTypes; all EntityType info is held in a MetadataStore ... of which there could be many.

We have to get the type from a MetadataStore; in this example we get it from the manager's metadataStore.

p.s.: you must have populated manager.metadataStore before calling this code, either implicitly as a side-effect of your first query or explicitly as when you call fetchMetadata.

Upvotes: 1

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