I have a function to spawn Enemies that will choose an entity name at random from a list. These names are strings, such as 'spider', 'mole', 'bee', etc. I want to then take that string and use it create an instance of the entity. Each Entity has its own script and behavior.
local entity = ENTITIES[math.random(1, #ENTITIES)]
new_entity = entity({
x = 0,
y = 0
})
Where entity could be "mole", instead of
if entity == 'mole' then Mole({
x = 0,
y = 0
})
elseif entity == 'spider' then Spider({
I am sure that this question has been answered, but I don't quite know how to look it up.
Thanks!
The simplest and also probably the nicest is to simply use a table of constructors:
local ENTITY_CONSTRUCTORS = {
spider=Spider,
mole=Mole,
bat=Bat,
...
}
And then:
local entity = ENTITIES[math.random(#ENTITIES)]
local object = ENTITY_CONSTRUCTORS[entity]{ x=0, y=0 }
You may even simplify further by storing constructors directly in ENTITIES table:
ENTITIES = { Spider, Mole, Bat }
local object = ENTITIES[math.random(#ENTITIES)]{ x=0, y=0 }
Related
How do you grab an object based on its attribute (in this case, an ID that is assigned to it)? Here is an example of the code that I'm currently working on.
Ped = {} -- Ped class.
Ped.__index = Ped
gPedID = 0
gPedAdditionalID = "Shop"
function Ped.create(_type, _skin, _x, _y, _z)
local _ped = {}
setmetatable(_ped,Ped)
_ped.oType = _type
_ped.pedElement = createPed(_skin, _x, _y, _z)
_ped.ID = gPedID
gPedID = gPedID + 1
return _ped
end
function pedID(player, command)
-- code to grab the object based on the object.ID
end
I've tried to make a table that references the object, i.e:
generictable[_ped.ID] = _ped
But to no avail, I'm guessing the reason why is because it only copies the address, not the actual reference.
Help is much appreciated, thanks!
I am using this for classes:
http://pastebin.com/DHVXsH37
Here is my code:
require 'class'
-- General node class and functions
Node = class(function(node, ID, x, y)
node.nodetype = 'neutral';
node.id = ID;
node.x = x;
node.y = y;
node.fname = 'exnode.png'
end)
function Node:display()
print( self.fname )
local img = display.newImage( self.fname, self.x, self.y );
img:addEventListener( "tap", self.onTap )
end
When running the display function of an initialized instance. I get an error saying that self is not defined. How do I get the properties of the object?
As Etan said in the comment, make sure you call your method as object:method() and not as object.method() as in the first case self value is set to object and in the second case it's not set to anything (so has nil value). object:method(...) notation is a syntax sugar for object.method(object, ...).
Ok, I must be working too hard because I can't get my head around what it takes to use the Entity Framework correctly.
Here is what I am trying to do:
I have two tables: HeaderTable and DetailTable. The DetailTable will have 1 to Many records for each row in HeaderTable. In my EDM I set up a Relationship between these two tables to reflect this.
Since there is now a relationship setup between these tables, I thought that by quering all the records in HeaderTable, I would be able to access the DetailTable collection created by the EDM (I can see the property when quering, but it's null).
Here is my query (this is a Silverlight app, so I am using the DomainContext on the client):
// myContext is instatiated with class scope
EntityQuery<Project> query = _myContext.GetHeadersQuery();
_myContext.Load<Project>(query);
Since these calls are asynchronous, I check the values after the callback has completed. When checking the value of _myContext.HeaderTable I have all the rows expected. However, the DetailsTable property within _myContext.HeaderTable is empty.
foreach (var h in _myContext.HeaderTable) // Has records
{
foreach (var d in h.DetailTable) // No records
{
string test = d.Description;
}
I'm assuming my query to return all HeaderTable objects needs to be modified to somehow return all the HeaderDetail collectoins for each HeaderTable row. I just don't understand how this non-logical modeling stuff works yet.
What am I doing wrong? Any help is greatly appriciated. If you need more information, just let me know. I will be happy to provide anything you need.
Thanks,
-Scott
What you're probably missing is the Include(), which I think is out of scope of the code you provided.
Check out this cool video; it explained everything about EDM and Linq-to-Entities to me:
http://msdn.microsoft.com/en-us/data/ff628210.aspx
In case you can't view video now, check out this piece of code I have based on those videos (sorry it's not in Silverlight, but it's the same basic idea, I hope).
The retrieval:
public List<Story> GetAllStories()
{
return context.Stories.Include("User").Include("StoryComments").Where(s => s.HostID == CurrentHost.ID).ToList();
}
Loading the the data:
private void LoadAllStories()
{
lvwStories.DataSource = TEContext.GetAllStories();
lvwStories.DataBind();
}
Using the data:
protected void lvwStories_ItemDataBound(object sender, ListViewItemEventArgs e)
{
if (e.Item.ItemType == ListViewItemType.DataItem)
{
Story story = e.Item.DataItem as Story;
// blah blah blah....
hlStory.Text = story.Title;
hlStory.NavigateUrl = "StoryView.aspx?id=" + story.ID;
lblStoryCommentCount.Text = "(" + story.StoryComments.Count.ToString() + " comment" + (story.StoryComments.Count > 1 ? "s" : "") + ")";
lblStoryBody.Text = story.Body;
lblStoryUser.Text = story.User.Username;
lblStoryDTS.Text = story.AddedDTS.ToShortTimeString();
}
}
I'm currently inserting/updating fields like this (if there's a better way, please say so - we're always learning)
public void UpdateChallengeAnswers(List<ChallengeAnswerInfo> model, Decimal field_id, Decimal loggedUserId)
{
JK_ChallengeAnswers o;
foreach (ChallengeAnswerInfo a in model)
{
o = this.FindChallengeAnswerById(a.ChallengeAnswerId);
if (o == null) o = new JK_ChallengeAnswers();
o.answer = FilterString(a.Answer);
o.correct = a.Correct;
o.link_text = "";
o.link_url = "";
o.position = FilterInt(a.Position);
o.updated_user = loggedUserId;
o.updated_date = DateTime.UtcNow;
if (o.challenge_id == 0)
{
// New record
o.challenge_id = field_id; // FK
o.created_user = loggedUserId;
o.created_date = DateTime.UtcNow;
db.JK_ChallengeAnswers.AddObject(o);
}
else
{
// Update record
this.Save();
}
}
this.Save(); // Commit changes
}
As you can see there is 2 times this.Save() (witch invokes db.SaveChanges();)
when Adding we place the new object into a Place Holder with the AddObject method, in other words, the new object is not committed right away and we can place as many objects we want.
But when it's an update, I need to Save first before moving on to the next object, is there a method that I can use in order to, let's say:
if (o.challenge_id == 0)
{
// New record
o.challenge_id = field_id;
o.created_user = loggedUserId;
o.created_date = DateTime.UtcNow;
db.JK_ChallengeAnswers.AddObject(o);
}
else
{
// Update record
db.JK_ChallengeAnswers.RetainObject(o);
}
}
this.Save(); // Only save once when all objects are ready to commit
}
So if there are 5 updates, I don't need to save into the database 5 times, but only once at the end.
Thank you.
Well if you have an object which is attached to the graph, if you modify values of this object, then the entity is marked as Modified.
If you simply do .AddObject, then the entity is marked as Added.
Nothing has happened yet - only staging of the graph.
Then, when you execute SaveChanges(), EF will translate the entries in the OSM to relevant store queries.
Your code looks a bit strange. Have you debugged through (and ran a SQL trace) to see what is actually getting executed? Because i can't see why you need that first .Save, because inline with my above points, since your modifying the entities in the first few lines of the method, an UPDATE statement will most likely always get executed, regardless of the ID.
I suggest you refactor your code to handle new/modified in seperate method. (ideally via a Repository)
Taken from Employee Info Starter Kit, you can consider the code snippet as below:
public void UpdateEmployee(Employee updatedEmployee)
{
//attaching and making ready for parsistance
if (updatedEmployee.EntityState == EntityState.Detached)
_DatabaseContext.Employees.Attach(updatedEmployee);
_DatabaseContext.ObjectStateManager.ChangeObjectState(updatedEmployee, System.Data.EntityState.Modified);
_DatabaseContext.SaveChanges();
}
I have an entity with two fk's. I've been trying to insert a record to the database without success. This are the approaches I've used:
valuePaymentBetToAdd.BetType = db.BetTypes.First(betType => betType.Id == valuePaymentBetToAdd.BetType.Id);
valuePaymentBetToAdd.Lottery = db.Lotteries.First(lotto => lotto.Id == valuePaymentBetToAdd.Lottery.Id);
In this case the second object gets assigned but when calling the SaveChanges method I get an error saying that the properties of the Lottery object were null.
valuePaymentBetToAdd.BetTypeReference.EntityKey = new EntityKey(db.DefaultContainerName + ".BetType", "Id", valuePaymentBetToAdd.BetType.Id);
valuePaymentBetToAdd.LotteryReference.EntityKey = new EntityKey(db.DefaultContainerName + ".Lottery", "Id", valuePaymentBetToAdd.Lottery.Id);
In this case I get another weird error. When the object is being added to the collection.
The object could not be added or attached because its EntityReference has an EntityKey property value that does not match the EntityKey for this object.
Am I missing something in this case?
Try setting the EntityReference like this:
valuePaymentBetToAdd.BetTypeReference.EntityKey = b.BetTypes.First(betType => betType.Id == valuePaymentBetToAdd.BetType.Id).EntityKey;
It works for me
How about creating a stub object for BetType and Lottery where you set only the Id property, and then attach those to their respective EntitySets, and then setting these objects on you Bet object, and save - something like:
Lottery lottery = new Lottery() { Id = valuePaymentBetToAdd.Lottery.Id };
BetType betType = new BetType() { Id = valuePaymentBetToAdd.BetType.Id };
MyContext.AttachTo("Lottery", lottery);
MyContext.AttachTo("BetType", betType);
valuePaymentBetToAdd.Lottery = lottery;
valuePaymentBetToAdd.BetType = betType;
MyContext.AddToBet(valuePaymentBetToAdd);
MyContext.SaveChanges();