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More perspicuous DSL for defining ContentProviders.
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@rst
rst committed Jul 22, 2012
1 parent eaf5f0c commit f9e7deb
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134 changes: 85 additions & 49 deletions src/main/scala/content/ContentExporter.scala
View file
Expand Up @@ -34,12 +34,12 @@ abstract class PositronicContentProvider
def onCreate: Boolean

/** Class used internally to represent everything we know about a
* request, including the `ParsedUriMatchCase` (q.v.) that handles it.
* request, including the `UriMatch` (q.v.) that handles it.
*/

case class ParsedRequest( reqType: ContentProviderReqType,
uri: Uri,
uriMatchCase: ParsedUriMatchCase,
uriMatchCase: BaseUriMatch,
matchValues: IndexedSeq[ ContentValue ],
vals: ContentValues,
where: String,
Expand All @@ -51,7 +51,7 @@ abstract class PositronicContentProvider
// can handle...

private[this]
val uriMatcher = new UriMatcher[ ParsedUriMatchCase ]
val uriMatcher = new UriMatcher[ BaseUriMatch ]

private[this]
def parsedRequestOption( reqType: ContentProviderReqType,
Expand Down Expand Up @@ -85,7 +85,7 @@ abstract class PositronicContentProvider
opt.getOrElse{ throw new UnsupportedUri( uri ) }
}

// Actual operations delegated to the ParsedUriMatchCase objects.
// Actual operations delegated to the UriMatch (or BaseUriMatch) objects.

def getType( uri: Uri ) = {
val opt = parsedRequestOption( GetType, uri )
Expand Down Expand Up @@ -142,11 +142,11 @@ abstract class PositronicContentProvider
*
* If the return value of your `queryForParsedRequest` would defend
* only on the matched components of the URI, on the other hand,
* the `MatchCase` and `UriMatchCase` may let you get the job done
* the more full-featured `UriMatchCase` may let you get the job done
* with a lot less ceremony.
*/

abstract class ParsedUriMatchCase( uri: Uri )
abstract class BaseUriMatch( uri: Uri )
{
def this( s: String ) = this( Uri.parse( s ))

Expand All @@ -160,6 +160,36 @@ abstract class PositronicContentProvider

def queryForParsedRequest( req: ParsedRequest ): ContentQuery[_,_]

/** Utility routine to apply the given conditions and order to
* a `ContentQuery`. Most implementations of `queryForParsedRequest`
* will want to call this with some appropriate arguments (possibly
* massaged from those given in the original request itself.
*/

protected def augmentQuery( query: ContentQuery[_,_],
where: String,
whereValues: Seq[String],
order: String ) =
{
// Apply conditions, if any.

var augQuery =
if (where != null) {
if (whereValues != null)
query.where( where, (whereValues.map{ CvString(_) }): _*)
else
query.where( where )
}
else query

// Apply order, if any. (Ignored where it doesn't matter.)

if (order != null)
augQuery.order( order )
else
augQuery
}

/** ContentValues to actually use in inserts and updates. Ordinarily,
* these are exactly those supplied by the client, but this method may
* be overridden to add parent record IDs, perform safety or
Expand Down Expand Up @@ -203,67 +233,73 @@ abstract class PositronicContentProvider
}

/** Content "subprovider" handling all URIs matching a URI pattern.
* This is a special case of `ParsedUriMatchCase` above, which allows
* This is a special case of `BaseUriMatch` above, which allows
* for simpler, lower-ceremony handling for common cases.
*
* Constructor arguments are the pattern, the contentType for returned rows,
* and a function which will build a query from the matched components
* of the URI.
* Constructor arguments are:
*
* *) the pattern (URI or string)
* *) a sequence of names of columns corresponding to the matched values
* *) the contentType for returned rows,
* *) a `ContentQuery`
*
* For example, consider
* {{{
* new UriMatch( "todo_lists/=/items/=",
* Seq("todo_list_id", "_id"),
* rowContentType( TODO_ITEM_TYPE ),
* TodoDb("todo_items"))
* }}}
* For URIs matching this pattern, say, "todo_lists/33/items/45",
* the query on the underlying content repository will be
* {{{
* TodoDb("todo_items").whereEq( "todo_list_id" -> 33, "_id" -> 45 )
* }}}
* Also, for an insert or update operation, the supplied `ContentValues`
* will have the "todo_list_id" and "_id" columns forced to the values from
* the URI (so the caller is not required to supply them twice).
*
* These behaviors may be changed by overriding the `queryForParsedRequest`
* and `contentValues` methods, respectively --- although in this case, you
* might want to just make your own subclass of `BaseUriMatch` instead.
*/

class UriMatchCase(
class UriMatch(
uri: Uri,
columnsMatched: Seq[ String ],
val contentType: String,
val queryForMatch: IndexedSeq[ContentValue] => ContentQuery[_,_])
extends ParsedUriMatchCase( uri )
val baseQuery: ContentQuery[_,_])
extends BaseUriMatch( uri )
{
def this( uriStr: String, columnsMatched: Seq[String],
contentType: String, baseQuery: ContentQuery[_,_] ) =
this( Uri.parse( uriStr ), columnsMatched, contentType, baseQuery )

/** Default order to use on queries, if not otherwise specified */

def defaultOrder = null

def queryForParsedRequest( req: ParsedRequest ) = {
def queryForParsedRequest( req: ParsedRequest ): ContentQuery[_,_] = {

var query = queryForMatch( req.matchValues )

// Apply conditions, if any.

query =
if (req.where != null) {
if (req.whereValues != null)
query.where( req.where, (req.whereValues.map{ CvString(_) }): _*)
else
query.where( req.where )
}
else query

// Apply order, if any. (Ignored where it doesn't matter.)
val query =
if (columnsMatched != Seq.empty)
baseQuery.whereEq( columnsMatched.zip( req.matchValues ): _*)
else
baseQuery

val order = if (req.order != null) req.order else defaultOrder

if (order != null)
query = query.order( order )

// Return what we got
augmentQuery( query, req.where, req.whereValues, order )
}

override def contentValues( req: ParsedRequest ) = {

query
for (( col, value ) <- columnsMatched.zip( req.matchValues ))
value.putContentValues( req.vals, col )

req.vals
}
}

/** Content "subprovider" handling all URIs matching a string pattern.
* This is a special case of `ParsedUriMatchCase` above, which allows
* for simpler, lower-ceremony handling for common cases.
*
* Constructor arguments are the pattern, the contentType for returned rows,
* and a function which will build a query from the matched components
* of the URI.
*/

class MatchCase(
str: String,
contentType: String,
queryForMatch: IndexedSeq[ContentValue] => ContentQuery[_,_]
)
extends UriMatchCase( Uri.parse( str ), contentType, queryForMatch )
}

/** Type of a request in a provider's ParsedRequest objects. One of the
Expand Down
42 changes: 14 additions & 28 deletions src/test/scala/ContentExporterSpec.scala
View file
Expand Up @@ -28,7 +28,7 @@ class TodoProvider extends PositronicContentProvider

// Queries for todo lists...

trait ListOps extends UriMatchCase {
trait ListOps extends UriMatch {

// When deleting a list, or several, we also want to delete the items...

Expand All @@ -54,39 +54,25 @@ class TodoProvider extends PositronicContentProvider
}
}

new UriMatchCase( TODO_LISTS_URI,
dirContentType( TODO_LIST_TYPE ),
r => TodoDb("todo_lists"))
new UriMatch( TODO_LISTS_URI, Seq.empty,
dirContentType( TODO_LIST_TYPE ),
TodoDb("todo_lists"))
with ListOps

new MatchCase( TODO_LISTS_PREFIX+"/=",
rowContentType( TODO_LIST_TYPE ),
r => TodoDb("todo_lists").whereEq( "_id" -> r(0) ))
new UriMatch( TODO_LISTS_PREFIX+"/=", Seq("_id"),
rowContentType( TODO_LIST_TYPE ),
TodoDb("todo_lists"))
with ListOps

// Queries for todo items...
// Queries for items

trait ItemOps extends UriMatchCase {
new UriMatch( TODO_LISTS_PREFIX+"/=/items", Seq("todo_list_id"),
dirContentType( TODO_ITEM_TYPE ),
TodoDb("todo_items"))

// Take todo_list_id from URI on inserts/updates, *not* the ContentValues

override def contentValues( req: ParsedRequest ) = {
val listId = req.matchValues(0) // the same in all our URI patterns
listId.putContentValues( req.vals, "todo_list_id" )
req.vals
}
}

new MatchCase( TODO_LISTS_PREFIX+"/=/items",
dirContentType( TODO_ITEM_TYPE ),
r => TodoDb("todo_items").whereEq( "todo_list_id" -> r(0)))
with ItemOps

new MatchCase( TODO_LISTS_PREFIX+"/=/items/=",
rowContentType( TODO_ITEM_TYPE ),
r => TodoDb("todo_items").whereEq("todo_list_id" -> r(0),
"_id" -> r(1)))
with ItemOps
new UriMatch( TODO_LISTS_PREFIX+"/=/items/=", Seq("todo_list_id", "_id"),
rowContentType( TODO_ITEM_TYPE ),
TodoDb("todo_items"))

// Test scaffolding for change notifications --- verify that we're notifying
// on the right URIs with the content resolver by mocking out the routine
Expand Down

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