In Azure DocumentDB, how can I get a list of all properties in a collection?

问题

I would like to be able to provide a list of all the properties across all documents in a collection.

The best way I can come up with is to query for all documents and then build the list in the client, but this feels wrong.

回答1:

The only way to do what you want is to read all of the documents. However, if you are worried about bandwidth, then you can do it in a stored procedure that only returns the list of properties.

If you take that route, I recommend that you start with the countDocuments sproc here and be prepared to call as many times as necessary until the continuation comes back empty and there are no 429 errors... or use documentdb-utils which takes care of that for you.

Alternatively, I could give you a full on example here. Just let me know.

Another approach would be to maintain a list of properties as documents are being written. This would be preferred if you need this list often.

回答2:

You can store Documents with any kind of structure in a collection, they could be all different. You are not restricted in a collection to store all objects from the same "schema".

So, getting all the properties available on a collection is not really something supported by the DocumentDB API or SDK, you either, read the whole collection, or rely on some sort of convention that you make when you create objects.

回答3:

You can use Slazure for this. Example follows which lists all property names for a given set of documents:

using SysSurge.Slazure.AzureDocumentDB.Linq;
using SysSurge.Slazure.Core;
using SysSurge.Slazure.Core.Linq.QueryParser;

public void ShowPropertyNames()
{
    // Get a reference to the TestCstomers collection
    dynamic storage = new QueryableStorage<DynDocument>("URL=https://contoso.documents.azure.com:443/;DBID=DDBExample;TOKEN=VZ+qKPAkl9TtX==");
    QueryableCollection<DynDocument> collection = storage.TestCustomers;

    // Build collection query
    var queryResult = collection.Where("SignedUpForNewsletter = true and Age < 22");

    foreach (DynDocument document in queryResult)
    {
        foreach (KeyValuePair<string, IDynProperty> keyValuePair in document)
        {
            Console.WriteLine(keyValuePair.Key);
        }
    }
}

来源：https://stackoverflow.com/questions/34406528/in-azure-documentdb-how-can-i-get-a-list-of-all-properties-in-a-collection

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azure

azure-cosmosdb