5 files changed, 45 insertions, 21 deletions
diff --git a/acf/model/model.lua b/acf/model/model.lua
index 365fe20..e94d3fb 100644
--- a/acf/model/model.lua
+++ b/acf/model/model.lua
@@ -71,18 +71,20 @@ function Model:init(context)
       return isinstance(res, Field) and node.BoundField(self, res) or nil
    end
 
+   function mt.has_field(name) return mt.field(name) end
+
    function mt.mmeta(name) return mt.field(name):meta() end
 
-   function mt.get(k)
+   function mt.load(k, create)
       local f = mt.field(k)
       if f then
 	 if f.compute then return f:compute() end
-	 return f:load()
+	 return f:load(create)
       end
       return mt.class[k]
    end
 
-   function mt.set(k, v)
+   function mt.save(k, v)
       local f = mt.field(k)
       if not f then raise(mt.path, 'Field named '..k..' does not exist') end
       f:save(v)
diff --git a/acf/model/node.lua b/acf/model/node.lua
index b73cf52..748b20d 100644
--- a/acf/model/node.lua
+++ b/acf/model/node.lua
@@ -53,9 +53,10 @@ function TreeNode:init(context)
    local mt = getmetatable(self)
    update(mt, context)
 
-   function mt.set(k, v) rawset(self, k, v) end
+   function mt.save(k, v) rawset(self, k, v) end
+   function mt.get(k, create) return mt.load(k, create) end
    function mt.__index(t, k) return mt.get(k) end
-   function mt.__newindex(t, k, v) mt.set(k, v) end
+   function mt.__newindex(t, k, v) mt.save(k, v) end
 
    function mt.has_permission(user, permission)
       local p = permission..mt.path
@@ -72,19 +73,28 @@ function TreeNode:init(context)
    mt.txn.validable[mt.path] = mt.addr
 end
 
-function TreeNode:search(path)
+function TreeNode:search(path, create)
+   if type(path) == 'string' then path = pth.split(path) end
+
    if #path == 0 then return self end
 
-   local cpath = getmetatable(self).path
+   local mt = getmetatable(self)
    local name = path[1]
-   local next = self[name]
-   if next == nil then raise(cpath, 'Subordinate does not exist: '..name) end
+   if not mt.has_field(name) then
+      raise(mt.path, 'Field does not exist: '..name)
+   end
+
+   local next = mt.get(name, create)
+   if next == nil and (not create or #path > 1) then
+      raise(mt.path, 'Subordinate does not exist: '..name)
+   end
 
    table.remove(path, 1)
    if #path > 0 and type(next) ~= 'table' then
-      raise(pth.join(cpath, name), 'Is a primitive value')
+      raise(pth.join(mt.path, name), 'Is a primitive value')
    end
-   return TreeNode.search(next, path)
+
+   return TreeNode.search(next, path, create)
 end
 
 
@@ -100,6 +110,8 @@ function Collection:init(context, params)
 
    mt.field = BoundField(self, params.field)
    mt.meta = {type='collection', members=mt.field:meta('$')}
+
+   function mt.has_field(name) return true end
    function mt.mmeta(name) return mt.meta.members end
    function mt.members() return mt.txn:get(mt.addr) or {} end
 
@@ -109,8 +121,8 @@ function Collection:init(context, params)
       end
    end
    
-   function mt.get(k) return mt.field:load(k) end
-   function mt.set(k, v) mt.field:save(k, v) end
+   function mt.load(k, create) return mt.field:load(k, create) end
+   function mt.save(k, v) mt.field:save(k, v) end
 end
 
 
@@ -148,6 +160,6 @@ function pairs(tbl)
    if not object.isinstance(tbl, TreeNode) then return rawpairs(tbl) end
    local mt = getmetatable(tbl)
    local res = {}
-   for _, member in ipairs(mt.members()) do res[member] = mt.get(member) end
+   for _, member in ipairs(mt.members()) do res[member] = mt.load(member) end
    return rawpairs(res)
 end
diff --git a/acf/model/root.lua b/acf/model/root.lua
index a786064..8571527 100644
--- a/acf/model/root.lua
+++ b/acf/model/root.lua
@@ -5,20 +5,28 @@ See LICENSE file for license details
 
 module(..., package.seeall)
 
+local node = require('acf.model.node')
 local model = require('acf.model.model')
-local super = require('acf.object').super
+local object = require('acf.object')
+local pth = require('acf.path')
 
 
 RootModel = model.new()
 
 function RootModel:init(txn)
-   super(self, RootModel):init{txn=txn, path='/', addr='/volatile'}
+   object.super(self, RootModel):init{txn=txn, path='/', addr='/volatile'}
 end
 
 function RootModel:has_permission(user, permission)
    return permission == 'read'
 end
 
+function RootModel:meta(path)
+   local obj = self:search(path, true)
+   if object.isinstance(obj, node.TreeNode) then return node.meta(obj) end
+   return node.mmeta(self:search(pth.parent(path), true), pth.name(path))
+end
+
 function register(name, addr, field)
    RootModel[name] = model.to_field(field, addr)
 end
diff --git a/acf/model/set.lua b/acf/model/set.lua
index be6c2de..2ab9d6d 100644
--- a/acf/model/set.lua
+++ b/acf/model/set.lua
@@ -26,7 +26,7 @@ function Set:init(context, params)
    local mt = getmetatable(self)
    mt.meta.type = 'set'
 
-   function mt.__index(t, k) return find(self, k) and k end
+   function mt.get(k, create) return (create or find(self, k)) and k end
 
    function mt.__newindex(t, k, v)
       assert(v == nil)
@@ -35,15 +35,15 @@ function Set:init(context, params)
 
       local len = #mt.members()
       while i < len do
-	 mt.set(i, mt.get(i + 1))
+	 mt.save(i, mt.load(i + 1))
 	 i = i + 1
       end
-      mt.set(len, nil)
+      mt.save(len, nil)
    end
 end
 
 
 function add(set, value)
    local mt = getmetatable(set)
-   if not find(set, value) then mt.set(#mt.members() + 1, value) end
+   if not find(set, value) then mt.save(#mt.members() + 1, value) end
 end
diff --git a/acf/transaction/init.lua b/acf/transaction/init.lua
index 48b1832..4c48d94 100644
--- a/acf/transaction/init.lua
+++ b/acf/transaction/init.lua
@@ -125,7 +125,9 @@ function Transaction:set_multiple(mods)
    end
 end
 
-function Transaction:search(path) return self.root:search(pth.split(path)) end
+function Transaction:search(path) return self.root:search(path) end
+
+function Transaction:meta(path) return self.root:meta(path) end
 
 function Transaction:commit()
    self:check()