I have a collection of Item objects. Each item has a description. I want to iterate through the collection, and for each description attribute, I want to replace the word "deliver" to "send". The word "deliver" appears in each description. For ex:
item 1: We will deliver within 3 days.
item 2: We will deliver within 2 days.
item 3: We will deliver within 7 days.
...
For a simple search and replace, it sounds like you want something like this:
collection.each { |item| item.description.gsub!('deliver', 'send') }
If these are ActiveRecord objects or some such, you may also need an item.save in there.
If you need more powerful pattern matching,String#sub and related methods can accept a regex instead of a string for the first argument, but it's probably faster and more readable to use a string if that's all you need. For more details and other options, see the API docs for String#sub.
Related
Straight forward here:
<% #yyy = CityRace.where(city_race_id2: "3") %>
<% #xxx = #yyy.name %>
The #yyy is returning the proper record using the ID I have passed into it, but I'm trying to get the objects name. For some reason .name isn't working. Any idea what I'm going wrong here?
How do I find a record's name where id = a certain id?
where returns an ActiveRecord_Relationship, meaning an object containing CityRace objects for every row in the database with city_race_id2 equals to 3, no matter if there's only one, the result is an ActiveRecord_Relationship object, and that doesn't respond to name.
If you need the name of a particular object from that result, you can access to the specific element by its index and invoke name on it, e.g:
CityRace.where(city_race_id2: "3").first.name
Or to retrieve the name from every object:
CityRace.where(city_race_id2: "3").pluck(:name)
this one returns an array of strings, so, you must iterate over them to print them all or get a specific one.
In the other hand if you need a single row from the query, use find_by:
CityRace.find_by(city_race_id2: "3").name
.where returns an ActiveRecord::Relation which behaves like an array. You can think of it like a special kind of array that allows you to chain on more active record queries on it. When you call certain methods like each or to_a it evaluates the query into an actual array.
In any case, what you are looking for here is not something array-like. You want #yyy to refer to a single record.
Simple fix, just use find_by instead of where. Also take a look at https://api.rubyonrails.org/classes/ActiveRecord/FinderMethods.html#method-i-find and find vs find_by vs where
How to save multiple selected dropdown values into a single column in Grails?
Input will look like
<g:select name="item1Price" from="${1..10}"/>
<g:select name="item2Price" from="${1..10}"/>
<g:select name="item3Price" from="${1..10}"/>
And Output Should be stored in one field
ItemPrice: 2,8,6
Your question is a bit vague, so hopefully a somewhat vague answer will be helpful too!
If you have a domain object Foo:
class Foo {
String itemPrice
}
Then in your controller action, you can just do something like:
def save() {
Foo f = new Foo()
f.itemPrice = [params.item1Price, params.item2Price, params.item3Price].join(",")
f.save()
}
Really all you're trying to do is join your parameters from your page into one string, right?
Now this actually seems like bad design to me. What happens if the order changes, or if nothing is selected for item 2? Or what happens if somebody wants to edit your object and you need to parse the values back out? Obviously you could split on commas...until one of the values contains a comma!
You're better off storing one value for each field that means something different, or storing a single field as a structured value. You might want to look at encoding a Map into JSON and storing that, for example, if you really just want to have one field in your domain object.
I just wasted half a day trying to figure this out, reading about some workarounds, and thinking "it can't be that bad - there must be a straightforward to do edit a collection in Grails, whethere using scaffolded views or my own."
Let's say I have this domain object:
class TreeGroup {
String name
List<Tree> trees
static hasMany = ['trees': MyTree]
}
Just to explain the choice of data structure - I need my records to be unique, but in the order I set. That's why I chose List, AFAIK one cannot rely on order in a Set. So there are 2 pieces to this question - 1) how to remove from any Collection, for example a Set, 2) is List the best replacement for Set in this context (preserving order).
I want to be able to create a group record with no trees in it and make 4 updates:
edit/save
edit the group record to reference 2 trees A and B
add another tree C
remove A
remove B and C
And obviously, I want the desired state after every step. Currently though, I can only add records, and if I even edit/save to list, the list elements are added to it again.
I am using the multiple select tag for this. It looks like this:
<g:select name="trees" from="${allTrees}" optionKey="id"
multiple="true" class="many-to-many"
value="${trees ? trees*.id : treeGroupInstance?.trees*.id}" />
and that's fine, in the sense that it generates an HTTP header with these variables on update:
_method:PUT
version:19
name:d5
trees:1
_action_update:Update
But the data binder only adds new elements, it never lets you edit a list.
What is the cleanest way to do it ? Is it me, not reading something obvious, or is this a design flaw of grails data binding (and of so, when/how will it be fixed) ?
Is there a way perhaps via a hidden HTTP parameter to clear the list before (re)adding elements ?
Thanks
I ended up doing this:
private repopulate(def domainObject, String propertyName, Class domainKlaz) {
if (params[propertyName] != null) {
domainObject[propertyName].clear()
domainObject[propertyName].addAll(
params[propertyName].collect { domainKlaz.get(it) }
)
}
}
and I am calling it in update controller method before save(), for every collection. OMG how ugly.
My array contains a varying amount of objects. I need to iterate through the array and save each object id as a unique variable. Given the amount of objects within the array will vary, how should I do this?
"items"=>[{"id"=>"B00668BTCI"}, {"id"=>"B0041KJSL2"}]
I need to save the information to a new object that can support up to 16 IDs. #object.id_one, #object.id_two, etc...
The suitable way to save your data all depends upon how you want to reference it or access it later. Meta-programming is interesting and fun, but may be overkill depending upon your needs. You will need to determine that after looking at the choices. An alternative way is in an array:
array_of_ids = items.map(&:values).flatten
Or
array_of_ids = items.map { |item| item["id"] }
Then all of the IDs are in the array array_of_ids and becomes, in your example:
["B00668BTCI", "B0041KJSL2"]
Accessible by:
array_of_ids[0] # first id
array_of_ids[1] # second array
...
You need to do some meta-programming here...
Here is a post for you, it has an answer (by Chirantan) that shows how to create instance variables dynamically.
Hope this helps.
EDIT
Just in case you get interested to learn more, I have also found a good article about creating methods dynamically, check it out.
Dynamically adding class methods in Ruby by Ryan Angilly
Assume the following:
class Thing {
String name
List<String> tags
static constraints = {
name(nullable: false)
tags(nullable: false)
}
}
I want to know if its possible, using GORM, to run a query for domain instances based on values in their respective lists
For instance: Are there dynamic GORM finders to query things like 'Find all Things that have the tag "Video" ', or 'Find all things with name = "Product1" that have the tag "Image" '
Just want to know if there's a nice concise way of doing this with Grails&Gorm, as opposed to retrieving a list of Things and iterating through it, finding the ones that have the appropriate tags and adding them to a results list.
Thanks!
One way (although not necessarily the most efficient!) would be to return the whole list of Things eg Thing.list() and then filter the resulting list using findAll.
List results = Thing.list().findAll{it.tags.contains("Image")}
How big is your list of Things and associated Tags likely to be?