How to perform a complex search using ActiveRecord - ruby-on-rails-3

I have a search form with several fields and it currently works. I have written the search action in the following way:
conditions = {}
conditions[:x] = params[:x] unless params[:x].blank?
conditions[:y] = params[:y] unless params[:y].blank?
conditions[:z] = params[:z] unless params[:z].blank?
etc.
#results = Material.where(conditions)
And this is fine. But now I want to add a condition that says essentially "where the level is less than or equal to params[:level], which would look like this in my head:
conditions[:level] <= params[:level] ...
But this doesn't work because it seems you can only add hashes using this syntax. So my question is how I would add such a condition to the query.

You can't add this to your existing conditions hash. The hash key: value arguments to where can only produce where key = value, not key <= value.
Use a parameterized string and an additional where:
#results = Material.where(conditions).where("level <= ?", params[:level])

Related

Struggling with simple boolean WHERE clause

Tired brain - perhaps you can help.
My table has two bit fields:
1) TestedByPCL and
2) TestedBySPC.
Both may = 1.
The user interface has two corresponding check boxes. In the code I convert the checks to int.
int TestedBySPC = SearchSPC ? 1 : 0;
int TestedByPCL = SearchPCL ? 1 : 0;
My WHERE clause looks something like this:
WHERE TestedByPCL = {TestedByPCL.ToString()} AND TestedBySPC = {TestedBySPC.ToString()}
The problem is when only one checkbox is selected I want to return rows having the corresponding field set to 1 or both fields set to 1.
Now when both fields are set to 1 my WHERE clause requires both check boxes to be checked instead of only one.
So, if one checkbox is ticked return records with with that field = 1 , regardless of whether the other field = 1.
Second attempt (I think I've got it now):
WHERE ((TestedByPCL = {chkTestedByPCL.IsChecked} AND TestedBySPC = {chkTestedBySPC.IsChecked})
OR
(TestedByPCL = 1 AND TestedBySPC = 1 AND 1 IN ({chkTestedByPCL.IsChecked}, {chkTestedBySPC.IsChecked})))
Misunderstood the question.
Change the AND to an OR:
WHERE TestedByPCL = {chkTestedByPCL.IsChecked} OR TestedBySPC = {chkTestedBySPC.IsChecked}
Also:
SQL Server does not have a Boolean data type, it's closest option is a bit data type.
The usage of curly brackets suggests using string concatenations to build your where clause. This might not be a big deal when you're handling checkboxes but it's a security risk when handling free text input as it's an open door for SQL injection attacks. Better use parameters whenever you can.

Add conditions where with 2 field conditions do not run accurately

The data that appears does not match the conditions that have been applied
I implemented SQL code in the Navicat application, and have changed the structure of the code several times but it still doesn't work,
data that is not of ilart condition type
still appears
SELECT SERMAT,ILART,sum(GKSTP) as jumlah
FROM swift_zab_iw39
WHERE ILART='OVH' OR ILART='TST' and SERMAT='024147-000:09052'
GROUP BY ILART,SERMAT
Use IN operator:
WHERE ILART IN('OVH','TST') AND SERMAT = '024147-000:09052'
Add parenthesis to the OR condition in the WHERE clause as:
WHERE (ILART = 'OVH' OR ILART = 'TST') AND SERMAT = '024147-000:09052'

using .where with .find

I am wondering how I can use where cause with the ActiveRecord find method.
Here is the code I am using:
Supplier.joins(:products).find(params[:id]).where('suppliers.permalink = ? AND variants.master = ?', params[:id], TRUE)
which gives me:
undefined method `where' for #<Supplier:0x007fe49b4eb330>
Supplier.joins(:products).find(params[:id]).where('suppliers.permalink = ? AND variants.master = ?', params[:id], TRUE)
What you're doing here is finding the first record with the id contained in params[:id], then trying to run a where statement on that single record. where only works when run against the model itself.
The confusing part here is that you are using params[:id] both for the primary key (find searches the id field) but then also comparing it to the permalink column in the where clause.
To explain the usage of both methods:
find will search for result(s) from the table, matching the argument you provide it to the id field. You can pass in multiple id's and this method is mostly used to select a row that you know exists, by id. Most commonly it is used with a single id and returns a single instance.
where is used to find all results from the table that match the clause and return a collection of records. You can then refine these results or select one, for example by using .first:
Supplier.joins(:products).where('suppliers.permalink = ? AND variants.master = ?', params[:permalink], true).first
(Note that you're using joins(:products) but then querying variants table. Is this incorrect?)
Supplier.joins(:products).where('suppliers.permalink = ? AND variants.master = ?', params[:id], TRUE).find(params[:id])

How to Write a Where Clause to Handle Either a Specific Value or Any Value

I have a report with a table in Rails where users can optionally set filters like selecting a location or picking a range of dates and update the table via an ajax request.
Can I write this where clause so that it any date/blanks or all locations?
#orders = Order.where('created_at <= ? AND ? <= created_at AND location_id = ?', date_order_start, date_order_end, loc_filter)
The query above fails on blanks (e.g., "") and if I put nils they translate to nulls in the SQL.
To solve this problem right now I have a bunch of conditional statements that check whether value is present in the ajax request and then creates a different where clause depending on the case. My current conditionals are unwieldy, error prone and not scalable.
Searches on things like "wildcard sql" end up leading me to text searches (i.e., %) which I don't think fits in this case.
I am running on Rails 3.2 with postgresql.
I sometimes use an array of query statements and arguments like this:
queries = []
args = []
if some_condition
queries.push("created_at <= ?")
args.push(whatever_date)
end
if another_condition
queries.push("created_at >= ?")
args.push(another_date)
end
#order = Order.where(queries.join(" AND "), *args)

How to specify multiple values in where with AR query interface in rails3

Per section 2.2 of rails guide on Active Record query interface here:
which seems to indicate that I can pass a string specifying the condition(s), then an array of values that should be substituted at some point while the arel is being built. So I've got a statement that generates my conditions string, which can be a varying number of attributes chained together with either AND or OR between them, and I pass in an array as the second arg to the where method, and I get:
ActiveRecord::PreparedStatementInvalid: wrong number of bind variables (1 for 5)
which leads me to believe I'm doing this incorrectly. However, I'm not finding anything on how to do it correctly. To restate the problem another way, I need to pass in a string to the where method such as "table.attribute = ? AND table.attribute1 = ? OR table.attribute1 = ?" with an unknown number of these conditions anded or ored together, and then pass something, what I thought would be an array as the second argument that would be used to substitute the values in the first argument conditions string. Is this the correct approach, or, I'm just missing some other huge concept somewhere and I'm coming at this all wrong? I'd think that somehow, this has to be possible, short of just generating a raw sql string.
This is actually pretty simple:
Model.where(attribute: [value1,value2])
Sounds like you're doing something like this:
Model.where("attribute = ? OR attribute2 = ?", [value, value])
Whereas you need to do this:
# notice the lack of an array as the last argument
Model.where("attribute = ? OR attribute2 = ?", value, value)
Have a look at http://guides.rubyonrails.org/active_record_querying.html#array-conditions for more details on how this works.
Instead of passing the same parameter multiple times to where() like this
User.where(
"first_name like ? or last_name like ? or city like ?",
"%#{search}%", "%#{search}%", "%#{search}%"
)
you can easily provide a hash
User.where(
"first_name like :search or last_name like :search or city like :search",
{search: "%#{search}%"}
)
that makes your query much more readable for long argument lists.
Sounds like you're doing something like this:
Model.where("attribute = ? OR attribute2 = ?", [value, value])
Whereas you need to do this:
#notice the lack of an array as the last argument
Model.where("attribute = ? OR attribute2 = ?", value, value) Have a
look at
http://guides.rubyonrails.org/active_record_querying.html#array-conditions
for more details on how this works.
Was really close. You can turn an array into a list of arguments with *my_list.
Model.where("id = ? OR id = ?", *["1", "2"])
OR
params = ["1", "2"]
Model.where("id = ? OR id = ?", *params)
Should work
If you want to chain together an open-ended list of conditions (attribute names and values), I would suggest using an arel table.
It's a bit hard to give specifics since your question is so vague, so I'll just explain how to do this for a simple case of a Post model and a few attributes, say title, summary, and user_id (i.e. a user has_many posts).
First, get the arel table for the model:
table = Post.arel_table
Then, start building your predicate (which you will eventually use to create an SQL query):
relation = table[:title].eq("Foo")
relation = relation.or(table[:summary].eq("A post about foo"))
relation = relation.and(table[:user_id].eq(5))
Here, table[:title], table[:summary] and table[:user_id] are representations of columns in the posts table. When you call table[:title].eq("Foo"), you are creating a predicate, roughly equivalent to a find condition (get all rows whose title column equals "Foo"). These predicates can be chained together with and and or.
When your aggregate predicate is ready, you can get the result with:
Post.where(relation)
which will generate the SQL:
SELECT "posts".* FROM "posts"
WHERE (("posts"."title" = "Foo" OR "posts"."summary" = "A post about foo")
AND "posts"."user_id" = 5)
This will get you all posts that have either the title "Foo" or the summary "A post about foo", and which belong to a user with id 5.
Notice the way arel predicates can be endlessly chained together to create more and more complex queries. This means that if you have (say) a hash of attribute/value pairs, and some way of knowing whether to use AND or OR on each of them, you can loop through them one by one and build up your condition:
relation = table[:title].eq("Foo")
hash.each do |attr, value|
relation = relation.and(table[attr].eq(value))
# or relation = relation.or(table[attr].eq(value)) for an OR predicate
end
Post.where(relation)
Aside from the ease of chaining conditions, another advantage of arel tables is that they are independent of database, so you don't have to worry whether your MySQL query will work in PostgreSQL, etc.
Here's a Railscast with more on arel: http://railscasts.com/episodes/215-advanced-queries-in-rails-3?view=asciicast
Hope that helps.
You can use a hash rather than a string. Build up a hash with however many conditions and corresponding values you are going to have and put it into the first argument of the where method.
WRONG
This is what I used to do for some reason.
keys = params[:search].split(',').map!(&:downcase)
# keys are now ['brooklyn', 'queens']
query = 'lower(city) LIKE ?'
if keys.size > 1
# I need something like this depending on number of keys
# 'lower(city) LIKE ? OR lower(city) LIKE ? OR lower(city) LIKE ?'
query_array = []
keys.size.times { query_array << query }
#['lower(city) LIKE ?','lower(city) LIKE ?']
query = query_array.join(' OR ')
# which gives me 'lower(city) LIKE ? OR lower(city) LIKE ?'
end
# now I can query my model
# if keys size is one then keys are just 'brooklyn',
# in this case it is 'brooklyn', 'queens'
# #posts = Post.where('lower(city) LIKE ? OR lower(city) LIKE ?','brooklyn', 'queens' )
#posts = Post.where(query, *keys )
now however - yes - it's very simple. as nfriend21 mentioned
Model.where(attribute: [value1,value2])
does the same thing