I've been trying to build a react based application, and I am stumped with how to solve this situation:
Let's say I have a component called "SimpleTable" that provides as the name says, a simple table - the props for it are "headers" (array), "rows" (array) and "paginated" (bool)
If the paginated is false, then we just give a simple long table - if it is true, we chunk the rows to multiple small tables, and provide buttons to toggle prev/next - so far so simple.
Now comes the challenging part - I want to sometimes have the table as just a table in my code, and sometimes I want to wrap it in a "card" element. I have introduced a new prop to the component called "asCard" (bool), which changes the output of the HTML, and changes where the prev/next buttons are placed.
Is there a way to reverse this, so that instead of having "asCard" in my component, I would have a wrapper component that I can put anything in, and it can "extract" actions from the child component, and place them in a different position - this way I could have many different components, and would not have to worry about having "asCard" on each of them.
What I am thinking is maybe having a "Card" component, and have a function in it called something like "extractAction", and then it passes it to the child component, and the child component then has a check for a prop called "handleExtractAction" which then passes the action element to, instead of using it in its own output. But I am not sure if this is an overly complicated way of doing this, and if there is a more sensible way of doing it.
EDIT:
I'll try and add a visual example of what I am talking about
SimpleTable with pagination:
< >
item 1
------
item 2
------
item 3
------
item 4
------
item 5
------
SimpleTable inside a Card, with basic parent>child setup:
------------------------
| card title |
------------------------
| |
| < > |
| |
| item 1 |
| ------ |
| |
| item 2 |
| ------ |
| |
| item 3 |
| ------ |
| |
| item 4 |
| ------ |
| |
| item 5 |
| ------ |
------------------------
And the result that I would want to have instead, without having to use "asCard" in each custom component I create.
------------------------
| card title < >|
------------------------
| |
| item 1 |
| ------ |
| |
| item 2 |
| ------ |
| |
| item 3 |
| ------ |
| |
| item 4 |
| ------ |
| |
| item 5 |
| ------ |
------------------------
Related
What is the best way for storing enumerated fields with ability to change its order?
Lets say my database looks like this:
| Table |
|---------------------|
| id | name | order|
| 1 | 1st | 1 |
| 2 | 2nd | 2 |
| 3 | 3rd | 3 |
| 4 | 4th | 4 |
Now, when user change order in such a away
| Table |
|---------------------|
| id | name | order|
| 1 | 1st | 1 |
| 4 | 4nd | 2 |
| 2 | 2nd | 3 |
| 3 | 3rd | 4 |
Here I would have to update all rows in this table.
I consider 2 solutions
Solution 1)
When inserting row X between for example order 2 and order 3, I would change row's X order field to 3.5, So I would choose number in the middle between adjacent orders.
Above table would look like this
| Table |
|---------------------|
| id | name | order|
| 1 | 1st | 1 |
| 4 | 4nd | 2.5 |
| 2 | 2nd | 2 |
| 3 | 3rd | 3 |
Then, after for example 16 changes I would update table and normalize all order fields, so table after normalization would be like this:
| Table |
|---------------------|
| id | name | order|
| 1 | 1st | 1 |
| 4 | 4nd | 2 |
| 2 | 2nd | 3 |
| 3 | 3rd | 4 |
Solution 2)
I also consider adding fields "next" (or "next" and "prev") to each row, but it looks for me like waste of memory.
I really dont want to update whole table every time somebody change order. What is the best way of solving this problem?
I have a question related to a kind of duplication I see in databases from time to time. To ask this question, I need to set the stage a bit:
Let's say I have a database of TV shows. Its primary table Content stores information at various levels of granularity (Show -> Season -> Episode), using a parent column to denote hierarchy:
+----+---------------------------+-------------+----------+
| ID | ContentName | ContentType | ParentId |
+----+---------------------------+-------------+----------+
| 1 | Friends | Show | [null] |
| 2 | Season 1 | Season | 1 |
| 3 | The Pilot | Episode | 2 |
| 4 | The One with the Sonogram | Episode | 2 |
+----+---------------------------+-------------+----------+
Maybe this isn't ideal, but let's say it's good enough to work with and we're not looking to change it.
Now let's say we need to build a table that defines air dates. We can set these at any level, and they must apply down the hierarchy (e.g., if set at the Season level, it applies to all episodes within that season; if set at the Show level, it applies to all seasons and episodes).
So the original air dates might look like this:
+-------+-----------+------------+
| airId | ContentId | AirDate |
+-------+-----------+------------+
| 71 | 3 | 1994-09-22 |
| 72 | 4 | 1994-09-29 |
+-------+-----------+------------+
Whereas the air date for a streaming service might look like:
+-------+-----------+------------+
| airId | ContentId | AirDate |
+-------+-----------+------------+
| 91 | 1 | 2015-01-01 |
+-------+-----------+------------+
Cool. Everything's fine so far; we're adhering to 4NF (I think!) and we can proceed to our business logic.
Now we get to my question. If we implement our business logic in such a way that disregards the referential hierarchy, and instead duplicates the air dates down the hierarchy, what is this anti-pattern called? e.g., Let's say I set an air date at the Show level like above, but the business logic finds all child elements and creates an entry for each one, resulting in:
+-------+-----------+------------+
| airId | ContentId | AirDate |
+-------+-----------+------------+
| 91 | 1 | 2015-01-01 |
| 92 | 2 | 2015-01-01 |
| 93 | 3 | 2015-01-01 |
| 94 | 4 | 2015-01-01 |
+-------+-----------+------------+
There are some pretty clear problems with this, but please note that my question is not how to fix this. Just, is there a specific term for it? I want to call it something like, "disregarding data relationship" or, "ignoring referential context". Maybe it's not strictly a database anti-pattern, since in my example there's an external actor inserting the excess rows.
I have a table with thousands of items with a lot of attributes (approx 15+). I would like to select the following results:
Select all combination of items to have at least 100% from each attributes? Exactly 100% would be nice but thats not necessary so it can go over a little or be a little less (maybe +-2%).
All combinations would be a big dataset so I think it would be better to sort them by price and select only the 10 cheapest one.
Also if I would like to modify selects before so that one or several attributes cant get over some value, like 50% for example?
| ----------- | ------------ | ----------- | ----------- | ----- |
| item name | attribute 1 | attribute 2 | attribute 3 | price |
| item 1 | 25% | 1% | 5% | 1€ |
| item 2 | 10% | 10% | 10% | 2€ |
| item 3 | 5% | 20% | 5% | 3€ |
| item 4 | 20% | 15% | 50% | 12€ |
I don't know if there is an existing algorithm for my problem ( I hope so ) or my problem has a name I can google but I would be thankful for any tips how I should proceed.
The only way I could think of for now is to bruteforce all the combinations and drop the unusable ones. But I don't think that's the right way (maybe I'm wrong and thats the only way).
The number of items, price and attribute values can change over time. If they were static I would just run the bruteforce option once and be done with it.
Sorry if this question was already asked.
EDIT:
As an example I can provide nutritional information about food (All the numbers are made up):
daily intake of carbohydrates/fat/protein are 225g/30g/65g
| ----------- | --------------- | ------- | --------- | ------ | ----- |
| item name | carbohydrates | fat | protein | sodium | price |
| apple | 10g | 1g | 5g | 1mg | 1€ |
| banana | 20g | 2g | 10g | 1mg | 2€ |
| pear | 15g | 3g | 5g | 5mg | 3€ |
| ----------- | --------------- | ------- | --------- | ------ | ----- |
find me combination of foods which will reach daily intake.
Now i want the same as in 1. but sort it by the price/select the cheapest.
I want only combinations with sodium not exceeding 30mg
I'm trying to make a database that will hold a table of objects, and these objects are comprised of objects from a second table. One table is a table of possible sets, and the second is a table of possible components. The table of sets has to include fields for each of its components, but each set has an unknown number of components. How do I make a table with fields (Component 1, Component 2, Component 3, ...) that are dependent on each set to decide how many of the fields it needs?
Is there a way to do this just using the Access interface or will I actually have to get into the code behind it?
I think it would also solve my problem if there were a way to make a field in a column that acted as an ArrayList so if anyone could think of how to do that please let me know.
Assuming that a component can be part of more than one set, what you need here is a many-to-many relationship.
In a database you don't do this with an arbitrary number of columns, you use a junction table.
When you need a tabular representation, you use a Pivot / Crosstab query.
Your data model could look like this:
Sets
+--------+----------+
| Set_ID | Set_Name |
+--------+----------+
| 1 | foo |
| 2 | bar |
+--------+----------+
Components
+--------------+----------------+
| Component_ID | Component_Name |
+--------------+----------------+
| 1 | aaa |
| 2 | bbb |
| 3 | ccc |
| 4 | ddd |
+--------------+----------------+
Junction table
+----------+----------------+
| f_Set_ID | f_Component_ID |
+----------+----------------+
| 1 | 2 |
| 1 | 4 |
| 2 | 1 |
| 2 | 2 |
| 2 | 3 |
+----------+----------------+
(f_ as in Foreign Key)
I would like to build an html table based on a model.
I want to do something like that:
Student | competence 1 |
| subject 1 | subject 2|
| exam 1 | exam2 | average | |
xxxxx yyyyyyyyy | 10 | 20 | 15 | 45 |
And here is how I'm trying to do this:
table(ng-controller="ExaminationListCtrl")
tr
th(ng-repeat="(competence, s) in competenceToSubjectSize", colspan="{{s.length}}")
{{competence}}
tr
th(ng-repeat="subject in subjects")
{{subject.subject}}
My issue is that I can't use colspan="{{s.length}}", it seems to me that "competence" and s are only bound to the child of th elements
How could I achieve this?
I was wrong since the top tag we could access to the scope marked with the ng-repeat