I'd like to have something like this in a bean:
ownWheelList ownSpareList
Those two lists are of the same model type. Both hold wheelbeans.
So while the first is good the second is not. This is clear, because RedBeans awaits beans of type spare which do not exists.
Is it possible to do something like aliasing on list like it is on objects?
I can't see it working, when you use ownList, it means you'll find every registry that have a column named mainbean_id on each table (wheel and spare).
So if you want to differ wheel and spare you could use a type column such as wheel = 1 AND spare = 2, then you can load the list using a with condition like $mainbean->with("AND type = ?", [1])->ownWheelList to get wheel list and $mainbean->with("AND type = ?", [2])->ownWheelList to get spare list.
Related
I'm building a rails app for managing a queue of work items. I have several types of users ("access levels") to whom I want to auto-assign these work items.
The end goal is an "Auto-assign" button on one of my views that will automatically grab the next work item based on a priority, which is defined by the users's access level.
I'm trying to set up a class method in my work_item model to automatically sort work items by type based on the user's access level. I am looking at something like this:
def self.auto_assign_next(access_level)
case
when access_level = 2
where("completed = 'f'").order("requested_time ASC").limit(1)
when access_level > 2
where("completed = 'f'").order("CASE WHEN form='supervisor' THEN 1 WHEN form='installer' THEN 2 WHEN form='repair' THEN 3 WHEN form='mail' THEN 4 WHEN form='hp' THEN 5 ELSE 6 END").limit(1)
end
This isn't very DRY, though. Ideally I'd like the sort order to be configurable by administrators, so maybe setting up a separate table on which the sort order is kept would be best. The problem with that idea is that I have no idea how to pass the priority order on that table to the [postgre]SQL query. I'm new to SQL in general and somewhat lost with this one. Does anybody have any suggestions as to how this should be handled?
One fairly simple approach starts with turning your case statement into a new table, listing form values versus what precedence value they should be sorted by:
id | form | precedence
-----------------------------------
1 | supervisor | 1
2 | installer | 2
(etc)
Create a model for this, say, FormPrecedences (not a great name, but I don't totally grok your data model so pick one that better describes it). Then, your query can look like this (note: I'm assuming your current model is called WorkItems):
when access_level > 2
joins("LEFT JOIN form_precedences ON form_precedences.form = work_items.form")
.where("completed = 'f'")
.order("COALESCE(form_precedences.precedence, 6)")
.limit(1)
The way this works isn't as complicated as it looks. A "left join" in SQL simply takes all the rows of the table on the left (in this case, work_items) and, for each row, finds all the matching rows from the table on the right (form_precedences, where "matching" is defined by the bit after the "ON" keyword: form_precedences.form = work_items.form), and emits one combined row. If no match is found, a LEFT JOIN will still emit a row, but with all the right-hand values being NULL. A normal join would skip any rows with no right-hand match found.
Anyway, with the precedence data joined on to our work items, we can just sort by the precedence value. But, in case no match was found during the join above, that value will be NULL -- so, I use COALESCE (which returns the first of its arguments that's not NULL) to default to a precedence of 6.
Hope that helps!
I've got a search page with multiple inputs (text fields). These inputs may or may not be empty - depending on what the user is searching for.
In order to accommodate this I create a base searchQuery object that pulls in all the correct relationships, and then for each non-empty input I modify the query using the searchQuery.Where function.
If I place multiple conditions in the WHERE clause I get the following error:
Cannot compare elements of type 'System.Collections.Generic.ICollection`1'. Only primitive types, enumeration types and entity types are supported.
searchQuery = searchQuery.Where(Function(m) (
(absoluteMinimumDate < m.ClassDates.OrderBy(Function(d) d.Value).FirstOrDefault.Value) _
OrElse (Nothing Is m.ClassDates)
)
)
I know that code looks funky, but I was trying to format it so you didn't have to scroll horizontally to see it all
Now, if I remove the ORELSE clause, everything works (but of course I don't get the results I need).
searchQuery = searchQuery.Where(Function(m) (
(absoluteMinimumDate < m.ClassDates.OrderBy(Function(d) d.Value).FirstOrDefault.Value)
)
)
This one works fine
So, what am I doing wrong? How can I make a multi-condition where clause?
Multiple conditions in the Where isn't the problem. m.ClassDates Is Nothing will never be true and doesn't make sense in SQL terms. You can't translate "is the set of ClassDates associated with this record NULL?" into SQL. What you mean is, are there 0 of them.
If there are no attached ClassDate records, m.ClassDates will be an empty list. You want m.ClassDates.Count = 0 OrElse...
In the Nokogiri documentation you can find the following:
node.pointer_id # internal pointer number
This returns the internal pointer number as an integer. However, it states nowhere how this can be used to look up a node?
I would have expected something like this:
p_id = node.pointer_id
element = page.with_pointer_id(p_id)
UPDATE...to give you an idea of the use case.
I am caching lots of html pages as Nokogiri object and scan them for specific nodes. Those nodes I save to a hash, together with the number of occurence:
{"node1" => 8}
Right now its saving the whole node as key, but it would be so much more convenient to have an identifier for it. After clustering those hashes I want to retrieve the nodes again -> thats were the id should come in.
You can do this using the #traverse method available through the Nokogiri::XML::Document instance.
Here is #traverse wrapped in your #with_pointer_id method as a singleton.
class Nokogiri::XML::Document
def with_pointer_id(p_id)
traverse {|node| return node if node.pointer_id == p_id}
end
end
Now you can do this:
element = page.with_pointer_id(p_id)
This will find the node with a pointer_id matching p_id, if it exists.
Hopefully this is a little clearer. I'm sorry but I'm very new to coding in general. I have multiple tables that I have to query in succession in order to get to the correct array that I need. The following logic for the query is as follows:
this gives me an array based upon the store :id
store = Stores.find(params[:id])
this gives me another array based upon the param .location found in the table store where that value equals the row ID in the table Departments
department = Departments.find(store.location)
I need to preform one last query but in order to do so I need to figure out which day of the meeting is needed. In order to do this I have to create the parameter day_of_meeting found in the table Stores. I try to call it from the array above and create a new variable. In the Table Departments, I there are params such as day_1, day_2 and so on. I need to be able to call something like department.day_1 or department.day_2. Thus, I'm trying to actually create the variable by join the words "department.day_" to the variable store.day_of_meeting which would equal some integer, creating department.day_1...
which_day = ["department.day_", store.day_of_meeting].join("")
This query finds uses the value found from the variable department.day_1 to query table Meeting to find the values in the corresponding row.
meeting = Meeting.find(which_day)
Does this make my problem any clearer to understand?
findmethod can only accept parameters like Meeting.find(1) or Meeting.find("1-xx").
so, what you need is Meeting.find(department.send("day_" + store.day_of_meeting.to_s))
Hope to help!
I'm trying to figure out the best approach to display combined tables based on matching logic and input search criteria.
Here is the situation:
We have a table of customers stored locally. The fields of interest are ssn, first name, last name and date of birth.
We also have a web service which provides the same information. Some of the customers from the web service are the same as the local file, some different.
SSN is not required in either.
I need to combine this data to be viewed on a Grails display.
The criteria for combination are 1) match on SSN. 2) For any remaining records, exact match on first name, last name and date of birth.
There's no need at this point for soundex or approximate logic.
It looks like what I should do is extract all the records from both inputs into a single collection, somehow making it a set on SSN. Then remove the blank ssn.
This will handle the SSN matching (once I figure out how to make that a set).
Then, I need to go back to the original two input sources (cached in a collection to prevent a re-read) and remove any records that exist in the SSN set derived previously.
Then, create another set based on first name, last name and date of birth - again if I can figure out how to make a set.
Then combine the two derived collections into a single collection. The collection should be sorted for display purposes.
Does this make sense? I think the search criteria will limit the number of record pulled in so I can do this in memory.
Essentially, I'm looking for some ideas on how the Grails code would look for achieving the above logic (assuming this is a good approach). The local customer table is a domain object, while what I'm getting from the WS is an array list of objects.
Also, I'm not entirely clear on how the maxresults, firstResult, and order used for the display would be affected. I think I need to read in all the records which match the search criteria first, do the combining, and display from the derived collection.
The traditional Java way of doing this would be to copy both the local and remote objects into TreeSet containers with a custom comparator, first for SSN, second for name/birthdate.
This might look something like:
def localCustomers = Customer.list()
def remoteCustomers = RemoteService.get()
TreeSet ssnFilter = new TreeSet(new ClosureComparator({c1, c2 -> c1.ssn <=> c2.ssn}))
ssnFilter.addAll(localCustomers)
ssnFilter.addAll(remoteCustomers)
TreeSet nameDobFilter = new TreeSet(new ClosureComparator({c1, c2 -> c1.firstName + c1.lastName + c1.dob <=> c2.firstName + c2.lastName + c2.dob}))
nameDobFilter.addAll(ssnFilter)
def filteredCustomers = nameDobFilter as List
At this point, filteredCustomers has all the records, except those that are duplicates by your two criteria.
Another approach is to filter the lists by sorting and doing a foldr operation, combining adjacent elements if they match. This way, you have an opportunity to combine the data from both sources.
For example:
def combineByNameAndDob(customers) {
customers.sort() {
c1, c2 -> (c1.firstName + c1.lastName + c1.dob) <=>
(c2.firstName + c2.lastName + c2.dob)
}.inject([]) { cs, c ->
if (cs && c.equalsByNameAndDob(cs[-1])) {
cs[-1].combine(c) //combine the attributes of both records
cs
} else {
cs << c
}
}
}