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Gaelyk: How to Perform Data Warehouse Queries on Collection Attributes

The Gaelyk guide provides some good low-level wrappers for data warehousing and this Gaelyk google groups article describes a simple way to model relationships by simply storing keys in a collection on an entity.

My question is: how can I execute queries on values ​​in collections? Here is a sample code to clarify ...

def b1 = new Entity("Book")
b1.title = "Book1"
b1.save()

def b2 = new Entity("Book")
b2.title = "Book2"
b2.save()

def author1 = new Entity("Author")  
author1.books = [b1.key, b2.key]
author1.name = "Chris"
author1.save()

// It is easy to simply query the Author entity for a standard string property
def query = new Query("Author")
query.addFilter("name", Query.FilterOperator.EQUAL, "Chris")
PreparedQuery preparedQuery = datastore.prepare(query)
def authors = preparedQuery.asList(withLimit(1))
assert authors[0].name == "Chris"

// But I can't find out how to query a collection property eg books on the Author entity
def query2 = new Query("Author")
// I would like to do something to return the entity if the value is in the collection property
// eg if there could be something like 'CONTAINS' criteria ...
// Unfortunately Query.FilterOperator.CONTAINS doesn't exist...
query2.addFilter("books", Query.FilterOperator.CONTAINS, b2.key)
PreparedQuery preparedQuery2 = datastore.prepare(query2)
def authors2 = preparedQuery2.asList(withLimit(1))
assert authors2[0].name == "Chris"

How to create a query that looks for matches in an Entity collection property? those. how to recreate the functionality of the mythical query "FilterOperator.CONTAINS" above?

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3 answers

, :

Query.FilterOperator.EQUAL ( CONTAINS, ). , :

def query2 = new Query("Author")
query2.addFilter("books", Query.FilterOperator.EQUAL, b2.key)
PreparedQuery preparedQuery2 = datastore.prepare(query2)
def authors2 = preparedQuery2.asList(withLimit(1))
assert authors2[0].name == "Chris"

:)

, DataStore.

+6

- "". , .

def author1 = new Entity("Author")  
author1.name = "Chris"
author1.save()

def b1 = new Entity("Book")
b1.title = "Book1"
b1.authors = [author1.key]
b1.save()

author1.books = [ b1.key ]
author1.save()

def book = datastore.get(b1.key)    
def chrisAuthors = book.authors.findAll { authorKey -> datastore.get(authorKey).name == 'Chris' }
assert chrisAuthors.size() == 1
+3

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