I need to get a previous scene key in componentWillMount using react-native-router-flux to checkout what screen I come back from and make some action on condition. I looked through a lot but haven`t found an answer. Are there any ways to do that ?
You can achieve this via
Actions.prevScene,
which will return the key of the previous scene in your stack.
Its hard to tell, but easier is pass variable when navigating out, like there:
Actions.home({from: 'about'})
now, Home props contain from variable, and you can handle this.
#sftgf's solution should work, but on react-native-router-flux 4.0.0-beta.28, it erroneously returns the current scene for me.
This Gist worked and has the added benefit of getting other scenes on the stack:
import {Actions} from react-native-reouter-flux
export function getPreviousScene (jumpCount = 1) { // if nothing is passed, it defaults to 1
const index = Actions.prevState.routes.length - (jumpCount + 1) // because zero-based index
if (index >= 0) {
return Actions.prevState.routes[index].routeName
}
return 'home'
}
Related
What I am Doing
I am trying to create a Sudoku solver and generator in Vue. Right now, I have the solving algorithm set up, and just need to generate new problems. I am generating problems by creating a completed Sudoku problem (complete with no bugs), then I have to remove nodes so that there is still only 1 solution to the problem.
The Problem
When I try to access a node from the multi-dimensional array that represents the board, and change it to null (what I am using to display a blank node), the board does not update that value. I am changing it with the following code: newGrid[pos[0]][pos[1]] = null; (where pos[0] is the row, pos[1] is the column , and newGrid is grid we want to mutate). Note that the array is an array with 9 arrays inside, and each of those arrays has 9 numbers (or null) which represent the values for that position in the grid. To elaborate on the bug, if I put a console.log(newGrid), there are normal looking values, and no null.
What I Know and Have Tried
I know it has to do with this specific line, and the fact that I am setting the value equal to null because changing null to another value (i.e. newGrid[pos[0]][pos[1]] = 0;) works and changes the array. The reason I don't just use a value other than null is: null renders and nothing and other values (0) render as something (null nodes should be blank), null is simple to understand in this situation (the logic is node has null, node has nothing, node is blank), and null is already implemented throughout my codebase.
Additionally, if I use console.log(newGrid[pos[0]][pos[1]]), null (the correct output) is outputted, even though console.log(newGrid) shows a number there, not null. Also, oddly enough, this works for one specific node. In row 1 (indexing starts at 0), column 8, null is set. Even though the input (completed) grid is always different, this node is always set to null. Edit: this bug had to do with the input grid already having null here, so it actually doesn't let any nulls be set.
To summarize: I expect an array with a null in a few positions I update, but I get a number instead. Also, there are no errors when the Typescript compiles to Javascript or during runtime.
Code
Given that I am not exactly sure where the problem may be (i.e. maybe I create the array wrong) I am including the minimum code with a pastebin link to the whole file (this is the full code). To restate, the goal of this function is to remove nodes from the list (by replacing them with null) in order to create a Sudoku puzzle with one solution. The code on Stack Overflow only includes some of the whole file, and the pastebin link includes the rest.
//global.d.ts
type Nullable<T> = T | null;
type Grid = Array<Array<number | null>>;
import { Solver } from './Solve';
// Inside the function that does the main work
const rowLen: number = grid.length;
const colLen: number = grid[0].length;
let newGrid: Grid = grid; // Grid is a argument for this function
let fullNodes = GetFirstFull(grid, colLen, rowLen);
let fullNodesLen: number = fullNodes.length;
// Some stuff that figures out how many solutions there are (we only want 1) is excluded
if (solutions != 1) {
fullNodesLen++;
rounds--;
} else {
newGrid[pos[0]][pos[1]] = null;
}
Note that if anything seems confusing check out the pastebin or ask. Thank you so much for taking the time to look at my problem!
Also, it isn't just 0 that works, undefined also makes it set correctly. So, this problem seems to be something with the null keyword...
EDIT:
Given that no one has responded yet, I assume: my problem is a bit hard, there isn't enough information, my post isn't good quality, or not enough people have seen it. To control the problem of not enough information, I would like to include the function that calls this function (just to see if that might be related).
generate(context: ActionContext<State, any>) {
let emptyArray = new Array(9);
for (let i = 0; i < 9; ++i)
emptyArray[i] = [null, null, null, null, null, null, null, null, null];
const fullGrid = Solver(emptyArray);
const puzzle = fullGrid ? Remover(fullGrid, 6) : state.gridLayout;
context.commit('resetBoard', puzzle);
},
Note: If you aren't familiar with Vuex, what context.commit does is changes the state (except it is changing a global state rather than a component state). Given that this function isn't refactored or very easy to read code in the first place, if you have any questions, please ask.
To solve other potential problems: I have been working on this, I have tried a lot of console.log()ing, changing the reference (newGrid) to a deepcopy, moving stuff out of the if statements, verifying code execution, and changing the way the point on the newGrid is set (i.e. by using newgrid.map() with logic to return that point as null). If you have any questions or I can help at all, please ask.
I'm building an application which uses jointjs / rappid and I want to be able to avoid loops from occuring across multiple cells.
Jointjs already has some examples on how to avoid this in a single cell (connecting an "out" port to an "in" port of the same cell) but has nothing on how to detect and prevent loops from occuring further up in the chain.
To help understand, imagine each cell in the paper is a step to be completed. Each step should only ever be run once. If the last step has an "out" port that connects to the "in" port of the first cell, it will just loop forever. This is what I want to avoid.
Any help is greatly appreciated.
I actually found a really easy way to do this for anyone else who wishes to achieve the same thing. Simply include the graphlib dependancy and use the following:
paper.on("link:connect", function(linkView) {
if(graphlib.alg.findCycles(graph.toGraphLib()).length > 0) {
linkView.model.remove();
// show some error message here
}
});
This line:
graphlib.alg.findCycles(graph.toGraphLib())
Returns an array that contains any loops, so by checking the length we can determine whether or not the paper contains any loops and if so, remove the link that the user is trying to create.
Note: This isn't completely full-proof because if the paper already contains a loop (before the user adds a link) then simply removing the link that the user is creating won't remove any loop that exists. For me this is fine because all of my papers will be created from scratch so as long as this logic is always in place, no loops can ever be created.
Solution through graphlib
Based on Adam's graphlib solution, instead of findCycles to test for loops, the graphlib docs suggests to use the isAcyclic function, which:
returns true if the graph has no cycles and returns false if it does. This algorithm returns as soon as it detects the first cycle.
Therefore this condition:
if(graphlib.alg.findCycles(graph.toGraphLib()).length > 0)
Can be shortened to:
if(!graphlib.alg.isAcyclic(graph))
JointJS functions solution
Look up the arrays of ancestors and successors of a newly connected element and intersect them:
// invoke inside an event which tests if a specific `connectedElement` is part of a loop
function isElementPartOfLoop (graph, connectedElement) {
var elemSuccessors = graph.getSuccessors(connectedElement, {deep: true});
var elemAncestors = connectedElement.getAncestors();
// *** OR *** graph.getPredecessors(connectedElement, {deep: true});
var commonElements = _.intersection(elemSuccessors, elemAncestors);
// if an element is repeated (non-empty intersection), then it's part of a loop
return !_.isEmpty(commonElements);
}
I haven't tested this, but the theory behind the test you are trying to accomplish should be similar.
This solution is not as efficient as using directly the graphlib functions.
Prevention
One way you could prevent the link from being added to the graph is by dealing with it in an event:
graph.on('add', _.bind(addCellOps, graph));
function addCellOps (cell, collection, opt) {
if (cell.isLink()){
// test link's target element: if it is part of a loop, remove the link
var linkTarget = cell.getTargetElement();
// `this` is the graph
if(target && isElementPartOfLoop(this, linkTarget)){
cell.remove();
}
}
// other operations ....
}
UDATED
How do I go about this?
I got this from Main.hx:
function onMouseOver(e:MouseEvent){
if(Std.is(e.currentTarget, MovieClip)){
initializer (cast e.currentTarget,["scaleX",1.5,"scaleY",1.5])
}
}
Then this is the pointed function in my Animation Class
//here if i set mc:Dynamic everything goes great! but when this one
function initializer(mc:MovieClip, vars:Array<Dynamic>){
var varsLength:Int = Math.round(vars.length/2);
for(m in 0...varsLength){
ini[m] = mc[vars[2*m]];
}
}
then when i compile it, an error appears:
Error: Array access is not allowed in flash.display.MovieClip
How do I resolve this?
EDIT:
vars: are properties of the MovieClip, for example when I pass these parameters:
initializer (mcClip1,["scaleX",1.5,"scaleY",1.5])
so:
vars = ["scaleX",1.5,"scaleY",1.5]
and:
ini[m] will store "scaleX" and "scaleY"`
X-Ref: https://groups.google.com/forum/#!topic/haxelang/_hkyt__Rrzw
In AS3, you can access fields of an object via their String name using [] (array access). This is called Reflection.
In Haxe, Reflection works differently - you need to make use of the Reflect API.
It's considered bad practice - it's not type-safe, which means the compiler can do very little to help you with error messages, and it's quite slow as well. This is why the usage makes it very explicit that Reflection is actually going on (while in AS3, this fact is somewhat hidden). Consider if there are other ways of solving this problem that don't require Reflection.
Now, to get back to your example, here's what it would look like in Haxe:
function onMouseOver(e:MouseEvent){
if (Std.is(e.currentTarget, MovieClip)) {
initializer(cast e.currentTarget, ["scaleX", 1.5, "scaleY", 1.5])
}
}
function initializer(mc:MovieClip, vars:Array<Dynamic>) {
for (m in 0...Std.int(vars.length / 2)) {
ini[m] = Reflect.getProperty(mc, vars[2*m]);
}
}
Btw, your loop was running for too long since you only use half of the values in the array - if you don't divide it by two like I did, you'll end up with [scaleX, scaleY, null, null] instead of the desired [scaleX, scaleY].
I have records that have an index attribute to maintain their position in relation to each other.
I have a plugin that performs a renumbering operation on these records when the index is changed or new one created. There are specific rules that apply to items that are at the first and last position in the list.
If a new (or existing changed) item is inserted into the middle (not technically the middle...just somewhere between start and end) of the list a renumbering kicks off to make room for the record.
This renumbering process fires in a new execution pipeline...We are updating record D. When I tell record E to change (to make room for D) that of course fires the plugin on update message.
This renumbering is fine until we reach the end of the list where the plugin then gets into a loop with the first business rule that maintains the first and last record differently.
So I am trying to think of ways to pass a flag to the execution context spawned by the renumbering process so the recursion skips the boundary edge business rules if IsRenumbering == true.
My thoughts / ideas:
I have thought of using the Depth check > 1 but that isn't a reliable value as I can't explicitly turn it on or off....it may happen to work but that is not engineering a solid solution that is hoping nothing goes bump. Further a colleague far more knowledgeable than I said that when a workflow calls a plugin the depth value is off and can't be trusted.
All my variables are scoped at the execute level so as to avoid variable pollution at the class level....However if I had a dictionary object, tuple, something at the class level and one value would be the thread id and the other the flag value then perhaps my subsequent execution context could check if the same owning thread id had any values entered.
Any thoughts or other ideas on how to pass context information to a new pipeline would be greatly appreciated.
Per Nicknow sugestion I tried sharedvariables but they seem to be going out of scope...:
First time firing post op:
if (base.Stage == EXrmPluginStepStage.PostOperation)
{
...snip...
foreach (var item in RenumberSet)
{
Context.ParentContext.SharedVariables[recordrenumbering] = "googly";
Entity renumrec = new Entity("abcd") { Id = item.Id };
#region We either add or subtract indexes based upon sortdir
...snip...
renumrec["abc_indexfield"] = TmpIdx + 1;
break;
.....snip.....
#endregion
OrganizationService.Update(renumrec);
}
}
Now we come into Pre-Op of the recursion process kicked off by the above post-op OrganizationService.Update(renumrec); and it seems based upon this check the sharedvariable didn't carry over...???
if (!Context.SharedVariables.Contains(recordrenumbering))
{
//Trace.Trace("Null Set");
//Context.SharedVariables[recordrenumbering] = IsRenumbering;
Context.SharedVariables[recordrenumbering] = "Null Set";
}
throw invalidpluginexception reveals:
Sanity Checks:
Depth : 2
Entity: ...
Message: Update
Stage: PreOperation [20]
User: 065507fe-86df-e311-95fe-00155d050605
Initiating User: 065507fe-86df-e311-95fe-00155d050605
ContextEntityName: ....
ContextParentEntityName: ....
....
IsRenumbering: Null Set
What are you looking for is IExecutionContext.SharedVariables. Whatever you add here is available throughout the entire transaction. Since you'll have child pipelines you'll want to look at the ParentContext for the value. This can all get a little tricky, so be sure to do a lot of testing - I've run into many issues with SharedVariables and looping operations in Dynamics CRM.
Here is some sample (very untested) code to get you started.
public static bool GetIsRenumbering(IPluginExecutionContext pluginContext)
{
var keyName = "IsRenumbering";
var ctx = pluginContext;
while (ctx != null)
{
if (ctx.SharedVariables.Contains(keyName))
{
return (bool)ctx.SharedVariables[keyName];
}
else ctx = ctx.ParentContext;
}
return false;
}
public static void SetIsRenumbering(IPluginExecutionContext pluginContext)
{
var keyName = "IsRenumbering";
var ctx = pluginContext;
ctx.SharedVariables.Add(keyName, true);
}
A very simple solution: add a bit field to the entity called "DisableIndexRecalculation." When your first plugin runs, make sure to set that field to true for all of your updates. In the same plugin, check to see if "DisableIndexRecalculation" is set to true: if so, set it to null (by removing it from the TargetEntity entirely) and stop executing the plugin. If it is null, do your index recalculation.
Because you are immediately removing the field from the TargetEntity if it is true the value will never be persisted to the database so there will be no performance penalty.
symfony getLayout does not seem to work when layout is set via view.yml. Is there anyway to get this within the controller's action class method
I recently needed this. You can do it but you just need to return the entire view.yml contents as an array:
$view_array = sfViewConfigHandler::getConfiguration(array(sfConfig::get('sf_app_config_dir').'/view.yml'));
Just adjust the relative path from sf_app_config_dir (or use another marker) to get what you need.
It's not a trivial task. The view.yml, is not in the "scope" of the action.
Maybe, you can use setLayout in your action rather then in view.yml.
if you can't, for some reasons... you can try this method to reach datas in view.yml:
Is it possible to get a value from view.yml in an action
Execute the following code in the action. It works for both cases, layout set in the action or in the view.yml.
$controller = $this->getContext()->getController();
$view = $controller->getView($this->getModuleName(), $this->getActionName(), 'Success'); // viewName == 'Success' (default)
$layout_name = $view->getDecoratorTemplate(); // e.g expected: layout.php
Let us know if it works for you.