nosql - WHERE clause on an array in Azure DocumentDb

Question

In an Azure Documentdb document like this

{
"id": "WakefieldFamily",
"parents": [
    { "familyName": "Wakefield", "givenName": "Robin" },
    { "familyName": "Miller", "givenName": "Ben" }
],
"children": [
    {
        "familyName": "Merriam", 
        "givenName": "Jesse", 
        "gender": "female", 
        "grade": 1,
        "pets": [
            { "givenName": "Goofy" },
            { "givenName": "Shadow" }
        ]
    },
    { 
      "familyName": "Miller", 
      "givenName": "Lisa", 
      "gender": "female", 
      "grade": 8 
    }
],
  "address": { "state": "NY", "county": "Manhattan", "city": "NY" },
  "isRegistered": false
};

How do I query to get children whose pets given name is "Goofy" ?

Looks like the following syntax is invalid

Select * from root r
WHERE r.children.pets.givenName="Goofy"

Instead I need to do

Select * from root r
WHERE r.children[0].pets[0].givenName="Goofy"

which is not really searching through an array.

Any suggestion on how I should handle queries like these ?

Answer 1

You should take advantage of DocumentDB's JOIN clause, which operates a bit differently than JOIN in RDBMs (since DocumentDB deals w/ denormlaized data model of schema-free documents).

To put it simply, you can think of DocumentDB's JOIN as self-joins which can be used to form cross-products between nested JSON objects.

In the context of querying children whose pets given name is "Goofy", you can try:

SELECT 
    f.id AS familyName,
    c AS child,
    p.givenName AS petName 
FROM Families f 
JOIN c IN f.children 
JOIN p IN c.pets
WHERE p.givenName = "Goofy"

Which returns:

[{
    familyName: WakefieldFamily,
    child: {
        familyName: Merriam,
        givenName: Jesse,
        gender: female,
        grade: 1,
        pets: [{
            givenName: Goofy
        }, {
            givenName: Shadow
        }]
    },
    petName: Goofy
}]

Reference: http://azure.microsoft.com/en-us/documentation/articles/documentdb-sql-query/

Edit:

You can also use the ARRAY_CONTAINS function, which looks something like this:

SELECT food.id, food.description, food.tags
FROM food
WHERE food.id = "09052" or ARRAY_CONTAINS(food.tags.name, "blueberries")