(1) In my Canvas App I create a collection like this:
Collect(colShoppingBasket; {Category: varCategoryTitle ; Supplier: lblSupplier.Text ; ProductNumber: lblProductNumber.Text });;
It works - I get a collection. And whenever I push my "Add to shopping basket" button, an item are added to my collection.
(2) Now I want to sort the collection and then use the sorted output for other things.
This function sorts it by supplier. No problems here:
Sort(colShoppingBasket; Supplier)
(3) Then I want to display the SORTED version of the collection in various scenarios. And this is where the issue is. Because all I can do is manipulate a DISPLAY of the collection "colShoppingBasket" - (unsorted).
(4) What would be really nice would be the option to create and store a manipulated copy of the original collection. And the display that whereever I needed. Sort of:
Collect(colShoppingBasketSORTED; { Sort(colShoppingBasket; supplier) });; <--- p.s. I know this is not a working function
You could use the following:
ClearCollect(colShoppingBasketSorted, Sort(colShoppingBasket, Supplier))
Note that it is without the { }
This will Clear and Collect the whole colShoppingBasket sorted.
If you want to store the table in a single row in a collection, you can use
ClearCollect(colShoppingBasketSortedAlternative, {SingleRow: Sort(colShoppingBasket, Supplier)})
I wouldn't recommend this though because if you want to use the Sorted values you'd have to do something like this:
First(colShoppingBasketSortedAlternative).SingleRow -> this returns the first records of the colShoppingBasketSortedAlternative then gets the content of the SingleRow column, which in this case is a Collection
Note: You will need to replace the , with ; to work on your case
Related
I would like to 'upsert' a document in DynamoDB. That is, I would like to specify a key, and a set of field/value pairs. If no document exists with that key, I want one created with that key and the key/value pairs I specified. If a document exists with that key, I want the fields I specified to be set to the values specified (if those fields did not exist before, then they should be added). Any other, unspecified fields on the existing document should be left alone.
It seems I can do this pretty well with the UpdateItem call, when the field/value pairs I am setting are all top-level fields. If I have nested structures, UpdateItem will work to set the nested fields, as long as the structure exists. In other words, if my existing document has "foo": {}, then I can set "foo.bar": 42 successfully.
However, I don't seem to be able to set "foo.bar": 42 if there is no foo object already (like in the case where there is no document with the specified field at all, and my 'upsert' is behaving as an 'insert'.
I found a discussion on the AWS forums from a few years ago which seems to imply that what I want to do cannot be done, but I'm hoping this has changed recently, or maybe someone knows of a way to do it?
UpdateItem behaves like an "upsert" operation: The item is updated if it exists in the table, but if not, a new item is added (inserted).
http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/SQLtoNoSQL.UpdateData.html
That ("foo.bar": 42) can be achieved using the below query:
table.update_item(Key = {'Id' : id},
UpdateExpression = 'SET foo = :value1',
ExpressionAttributeValues = {':value1': {'bar' : 42}}
)
Hope this helps :)
I found this UpdateItem limitation (top level vs nested attributes) frustrating as well. Eventually I came across this answer and was able to work around the problem: https://stackoverflow.com/a/43136029/431296
It requires two UpdateItem calls (possibly more depending on level of nesting?). I only needed a single level, so this is how I did it:
Update the item using an attribute_exists condition to create the top level attribute as an empty map if it doesn't already exist. This will work if the entire item is missing or if it exists and has other pre-existing attributes you don't want to lose.
Then do the 2nd level update item to update the nested value. As long as the parent exists (ex: an empty map in my case) it works great.
I got the impression you weren't using python, but here's the python code to accomplish the upsert of a nested attribute in an item like this:
{
"partition_key": "key",
"top_level_attribute": {
"nested_attribute": "value"
}
}
python boto3 code:
def upsert_nested_item(self, partition_key, top_level_attribute_name, nested_attribute_name, nested_item_value):
try:
self.table.update_item(
Key={'partition_key': partition_key},
ExpressionAttributeNames={f'#{top_level_attribute_name}': top_level_attribute_name},
ExpressionAttributeValues={':empty': {}},
ConditionExpression=f'attribute_not_exists(#{top_level_attribute_name})',
UpdateExpression=f'SET #{top_level_attribute_name} = :empty',
)
except self.DYNAMODB.meta.client.exceptions.ConditionalCheckFailedException:
pass
self.table.update_item(
Key={'partition_key': partition_key},
ExpressionAttributeNames={
f'#{top_level_attribute_name}': top_level_attribute_name,
f'#{nested_attribute_name}': nested_attribute_name
},
ExpressionAttributeValues={f':{top_level_attribute_name}': nested_item_value},
UpdateExpression=f'SET #{top_level_attribute_name}.#{nested_attribute_name} = :{top_level_attribute_name}',
)
We have a hierarchical watch app.
The root controller is a table of menu items. That list of items is controlled by a server. The data is retrieved and stored in core data. The menu is populated the first time going into the app.
But I want this table to stay current. My thought was to add code to willActivate to check if there was changes, and reload the table. In my reload logic I call the same function I called the first time, which sets the menuTable.setNumberOfRows and creates each row. Looking at what I'm putting in the logs, it is going through this logic with a different count of rows and new labels. But the app on the watch shows the table with the old data.
How can I get this table to reload with the new information?
I've had this problem too and as rmp says, it still seems to be a bug in watchOS 1.0.1. The problem appears when you try to reload your tableView after run willActivate() and nothing will happen.
In my case, I reload the tableView after receive a reply from a delegate and then I reload all the content just if it's necessary. To achieve this, I remove all rows from a NSIndexSet and load again.
if isNecessary {
self.table.removeRowsAtIndexes(NSIndexSet(indexesInRange: NSMakeRange(0, maxItems)))
isNecessary = false
}
I've tried a lot of tricks but none has worked for me:
Force to reload rows by table.setNumberOfRows(0, withRowType: "data")
Setting parameters to empty text before assign new values
One thing you could do is to hide tableView before removing rows, and avoid the remove animation.
It is a bug in WatchKit. Seems like Apple doesn't handle the repetitive interface object correctly.
The general principle here is: Only insert or remove necessary rows after a table is created. Do not reload the whole table like what we usually do in iOS. It just doesn't work (or trigger the bug).
So specifically, you have to:
Do this in willActivated method. This is correct.
If this is the first load, before the table is even created, do what you are now doing – load all table rows.
For all following times, don't reload the table, fetch the new data and check the desired number of rows.
Compare with the current number of rows in the table, insert to or remove from the bottom of the existing table.
Now simply re-assign the new data to all existing rows. Again, do not reload.
It should work if you follow the above steps.
I have found what works best given the current state of watchkit is to remove all rows then re-populate the table.
Try something like this:
- (void)loadTableData{
//clear the table
[mainTableView setNumberOfRows:0 withRowType:#"myTableRow"];
//set the row count again
[mainTableView setNumberOfRows:numberOfRows withRowType:#"myTableRow"];
//populate table
}
Its pretty simple. As Apple hasn't provided any method to reload the data.
You can still achieve that by simply populating the rows for the tableview.
Below is the sample code:
for index in 0..<tracksTableView.numberOfRows {
if let controller = tracksTableView.rowController(at: index) as? EditPlaylistRowController {
controller.playingTrackId = self.playingTrackID
controller.sharedTrack = trackItems[index]
}
}
Use it whenever you want to refresh the data.
NOTE:
You can still make some conditional statements inside the row controller class.
Happy to help :)
I'm trying to generate unique id for label & input pairs.
After googling I now know that, unlike with handlebars, there is no array #index syntax extension in spacebars yet (also anybody knows why Blaze development has been inactive since the version 0.1 for past 5 months?).
So I ended up using the JS Array .map() solution inspired by this blog post and other posts. However, this solution returns label & input pairs of objects which DOM appears to be rendering the same on 'pagination' through Session.
Live example: http://meteorpad.com/pad/NXLtGXXD4yhYr9LHC
When clicking on first set of "Non-Indexed IDs" checkboxes, then next/previous, DOM will display new set of checkboxes correctly.
However clicking on the second set of "Indexed IDs" checkboxes below, then next/previous, DOM seems to retain the same checkboxes because one selected from the previous page remains checked on the next page.
What am I doing wrong or missing?
I also put the code on github for quick testing & refinement:
The solution, which I've found by looking at the ObserveSequence source, appears to be to give your generated objects a unique field called _id (generated like {{questionId}}:{{questionIndex}}:{{choiceIndex}}). See this meteorpad: http://meteorpad.com/pad/2EaLh8ZJncnqyejSr
I don't know enough about Meteor internals to say why, but this comment seems relevant:
// 'lastSeqArray' contains the previous value of the sequence
// we're observing. It is an array of objects with '_id' and
// 'item' fields. 'item' is the element in the array, or the
// document in the cursor.
//
// '_id' is whichever of the following is relevant, unless it has
// already appeared -- in which case it's randomly generated.
//
// * if 'item' is an object:
// * an '_id' field, if present
// * otherwise, the index in the array
//
// * if 'item' is a number or string, use that value
//
// XXX this can be generalized by allowing {{#each}} to accept a
// general 'key' argument which could be a function, a dotted
// field name, or the special #index value.
When the _id is absent, it uses the index in the array, so I guess ObserveSequence assumes it's the same object with changed fields, rather than a different object, so it re-uses the old elements rather than destroying them and recreating them. I suppose the name _id is chosen so that it works well with arrays generated by .fetch() on a Minimongo cursor.
I don't know if this is documented behaviour, or if it might change in the future.
I need to modify a field value for all records in a crossfilter before inserting new records.
The API doesn't say anything about it. Is there a way to do that ?
Even if it's a hack that would be really useful to me.
Looking at the code, the data array is held as a private local variable inside the crossfilter function so there's no way to get at it directly.
With that said, it looks like Crossfilter really tries to minimize the number of copies of the data it makes. So callback functions like the ones passed into crossfilter.dimension or dimension.filter are passed the actual records themselves from the data array (using the native Array.map) so any changes to make to the records will be made to the main records.
With that said, you obviously need to be very careful that you're not changing anything that is relied on by the existing dimensions, filters or groups. Otherwise you'll end up with data that doesn't agree with the internal Crossfilter structures and chaos will ensue.
The cool thing about .remove is it only removes entries that match the currently applied filters. So if you create a 'unique dimension' that returns a unique value for every entry in your dataset (like an ID column), you can have a function like this:
function editEntry(id, changes) {
uniqueDimension.filter(id); // filter to the item you want to change
var selectedEntry = uniqueDimension.top(1)[0]; // get the item
_.extend(selectedEntry, changes); // apply changes to it
ndx.remove(); // remove all items that pass the current filter (which will just be the item we are changing
ndx.add([selectedEntry]); // re-add the item
uniqueDimension.filter(null); // clear the filter
dc.redrawAll(); // redraw the UI
}
At the least you could do a cf.remove() then readd the adjusted data with cf.add().
I am working on a form which displays information about orders. Each order has a unique id, but they are not necessarily sequential on the form. Also, the number of fields can vary (one field per row on the form). The input into the form will not be mapped straight into the database, but will be added to the current value in the database, and then saved. An example of the form is in the picture below - the callout on the right shows the id for each row.
I know how to generate the form like this, but I can't work out how I can easily process each of these rows reliably. I also know how to give each of the fields a unique identifier, like name="order-23" or name="order[23]", but how can I translate that name so that I can update the related record in the database?
EDIT: One solution I can think of would be to iterate through every form field in the FormCollection, and if the name of the field matches the pattern, then I will extract the number from that field-name and process it.
However, I feel that there must be a much easier way to go about it - this method would likely involve a fair bit of string processing on each field, and there would possibly fall over if I have to add extra fields for each row later on.
Don't you have a list of IDs after postback? I believe you should not depend on what IDs are actually sent from the form, as anybody could change the IDs on the form to whatever they want, so it's a security issue. So you should after postback have a list of IDs you want to update (the same list you used to create the form with). In that case, you know exactly what id string you should use to retrieve the value from FormCollection.
In case you really can't get the list of IDs you are going to update, just use the FormCollection iteration as you suggested in your comment. The string processing is not that expensive in comparation with all other stuff being done at request processing.
If you have the names, then simply read the values by using Request.Form["order-23"] or re-create the controls in page pre-init and you'll have access to the values in your save event directly through the created controls.
I've done this loads in my CMS.
Essentially i sort of cheated.
The idea is something like this ....
render the form to the client, then look at the source code gneerated.
You should see that it generated a form tag with an action attribute.
When you click the submit button the form will be sent to that url so in the case of an order submission you would post the page back to OrderPage.aspx?OrderId=xxxx
then on the server you would build an update statement for your db that contained something like ...
"Update orders where order id =" + request.querystring["OrderId"]
So how do you update the action ...
In the calling page lets say you have a link called "New Order", when that link is clicked you need to do 2 things ...
redirect to this page.
generate an order id for this new order.
ok the first is simple, simply link it to this page.
the second ...
if this page is not a postback if(!IsPostback) { /* get a new id */ } depending on your order id's this may involve generating a new guid or doing something like getting the next number in a list by doing a select max(id) from a db.
once you have this new id you should still be in the page_load event.
this.form.Action = this.form.Action + "?OrderId=" + yourNewOrderId;
... tada ...
Send page back to the client.
view the source.