I have a PostgreSQL table with YAML data stored in a text field.
I'm attempting to find all instances of where a key has been changed from false to true.
audited_changes: {"hide_on_map"=>[false, true]}
I can easily find all instances of this key with a like query on the attribute hide_on_map
[3] pry(main)> like_query = ActiveRecord::Base.send(:sanitize_sql_like, 'hide_on_map')
Audited::Audit.where(auditable_type: 'Lot').where('audited_changes like ?', "%#{like_query}%").count
(245.8ms) SELECT COUNT(*) FROM "audits" WHERE "audits"."auditable_type" = $1 AND (audited_changes like '%hide\_on\_map%') [["auditable_type", "Lot"]]
=> 1710
However, adding double quotes breaks this
[4] pry(main)> like_query = ActiveRecord::Base.send(:sanitize_sql_like, '"hide_on_map"')
Audited::Audit.where(auditable_type: 'Lot').where('audited_changes like ?', "%#{like_query}%").count
(238.5ms) SELECT COUNT(*) FROM "audits" WHERE "audits"."auditable_type" = $1 AND (audited_changes like '%"hide\_on\_map"%') [["auditable_type", "Lot"]]
=> 0
Let alone the full query
[5] pry(main)> like_query = ActiveRecord::Base.send(:sanitize_sql_like, '"hide_on_map"=>[false, true]')
Audited::Audit.where(auditable_type: 'Lot').where('audited_changes like ?', "%#{like_query}%").count
(245.0ms) SELECT COUNT(*) FROM "audits" WHERE "audits"."auditable_type" = $1 AND (audited_changes like '%"hide\_on\_map"=>[false, true]%') [["auditable_type", "Lot"]]
=> 0
Started going down a rabbit hole of converting to JSONB but this adds several additional complications that I'd rather not have to solve. Suggestions on a properly formed LIKE clause?
For those asking, two examples of this query directly in SQL at the psql prompt.
select count(*) from audits where audited_changes like '%"hide\_on\_map"%';
select count(*) from audits where audited_changes like '%\"hide\_on\_map\"%';
Both resulted in 0 results.
The problem is that there is not a unique way to express that data in YAML:
hide_on_map:
- no
- yes
"hide_on_map": [false, true]
are both valid YAML representations of your data.
I fear you cannot avoid using some native type, or at least a "compacted" JSON text (which would contain literally '"hide_on_map":[false,true]'.
Related
I've got a model method that conditionally concatenates the user's username ("login") and real name, if they've saved a real name - otherwise it just shows the username. I'd like to rewrite the query in ActiveRecord or Arel.
It looks like I should use an Arel::Nodes::NamedFunction. But i don't understand how to do the conditional concatenation with a named function. (Does Arel know about "if"? I can't find any reference in the docs.)
def primer_values
connection.select_values(%(
SELECT CONCAT(users.login,
IF(users.name = "", "", CONCAT(" <", users.name, ">")))
FROM users
ORDER BY IF(last_login > CURRENT_TIMESTAMP - INTERVAL 1 MONTH,
last_login, NULL) DESC,
contribution DESC
LIMIT 1000
)).uniq.sort
end
There's also similarly a conditional in ORDER BY.
While generally I abhor Raw SQL in rails given this usage I'd leave it as is. Although I might change it to something a bit more idiomatic like.
User
.order(
Arel.sql("IF(last_login > CURRENT_TIMESTAMP - INTERVAL 1 MONTH,last_login, NULL)").desc,
User.arel_table[:contribution].desc)
.limit(1000)
.pluck(Arel.sql(
'CONCAT(users.login,
IF(users.name = "", "",
CONCAT(" <", users.name, ">")))'))
.uniq.sort
Converting this to Arel without abstracting it into an object of its own will damage the readability significantly.
That being said just to give you an idea; the first part would be 3 NamedFunctions
CONCAT
IF
CONCAT
Arel::Nodes::NamedFuction.new(
"CONCAT",
[User.arel_table[:name],
Arel::Nodes::NamedFuction.new(
"IF",
[User.arel_table[:name].eq(''),
Arel.sql("''"),
Arel::Nodes::NamedFuction.new(
"CONCAT",
[Arel.sql("' <'"),
User.arel_table[:name],
Arel.sql("'>'")]
)]
)]
)
A NamedFunction is a constructor for FUNCTION_NAME(ARG1,ARG2,ARG3) so any SQL that uses this syntax can be created using NamedFunction including empty functions like NOW() or other syntaxes like LATERAL(query).
I have a SQL request that is almost perfect (for what I want to do):
WITH liste_fichiers_joints AS (
SELECT
id_dans_table,
ARRAY_AGG (row_to_json(f)) ids_fichier
FROM
fichiers_joints fj
LEFT JOIN fichiers f ON f.id = fj.id_fichier
WHERE
nom_table = 'taches'
GROUP BY
id_dans_table
)
SELECT t.id, t.nom, lfj.ids_fichier
FROM taches t
JOIN liste_fichiers_joints lfj ON lfj.id_dans_table = t.id
As you may have guessed, I'd like to get in the same request getting all the tasks: the id of a task, the name of the task but also in an array all the ids and names of the attached files if there are any.
The result is nearly what I want, but the last column displays this:
{"{\"uuid\":\"fd809b1f-6849-4322-a654-67f70c46a435\",\"nom\":\"test.png\",\"date\":\"2020-11-17T01:21:24.223354\",\"status\":\"TMP\",\"id\":185}"}
I'd like to remove the uuid and status parts, I tried some subrequests, up to no avail.
Also, I'd like to remove the backslashes \, because otherwise it will be complicated to use this column as a JSON in my Javascript.
Does anybody has a clue?
Thanks in advance.
You can use json[b]_build_object() instead of row_to_json[b](): it accepts a list of key/value pairs, so you have fine-grained control about what is going into your objects.
Also, you most likely want a JSON array, rather than a Postgres array of JSON objects.
I would recommend changing this:
ARRAY_AGG (row_to_json(f)) ids_fichier
To:
jsonb_agg(
jsonb_build_object('nom', f.nom, 'date', f.date, 'id', f.id)
) as ids_fichier
I am trying to build a case query with distinct count in cakephp 3.
This is the query in SQL:
select COUNT(distinct CASE WHEN type = 'abc' THEN app_num END) as "count_abc",COUNT(distinct CASE WHEN type = 'xyz' THEN app_num END) as "count_xyz" from table;
Currently, I got this far:
$query = $this->find();
$abc_case = $query->newExpr()->addCase($query->newExpr()->add(['type' => 'abc']),' app_num','string');
$xyz_case = $query->newExpr()->addCase($query->newExpr()->add(['type' => 'xyz']),'app_num','string');
$query->select([
"count_abc" => $query->func()->count($abc_case),
"count_xyz" => $query->func()->count($xyz_case),
]);
But I can't apply distinct in this code.
Using keywords in functions has been a problem for quite some time, see for example this issue ticket: https://github.com/cakephp/cakephp/issues/10454.
This has been somewhat improved in https://github.com/cakephp/cakephp/pull/11410, so that it's now possible to (mis)use a function expression for DISTINCT as kind of a workaround, ie generate code like DISTINCT(expression), which works because the parentheses are being ignored, so to speak, as DISTINCT is not a function!
I'm not sure if this works because the SQL specifications explicitly allow parentheses to be used like that (also acting as a whitespace substitute), or because it's a side-effect, so maybe check that out before relying on it!
That being said, you can use the workaround from the linked PR until real aggregate function keyword support is being added, ie do something like this:
"count_abc" => $query->func()->count(
$query->func()->DISTINCT([$abc_case])
)
This would generate SQL similar to:
(COUNT(DISTINCT(CASE WHEN ... END)))
I'm having trouble using ruby with dbi for some reason, I'm trying to do a select and put the results in an array but no luck.
require 'dbi'
db = DBI.connect('DBI:OCI8:database', XXXX, XXXX)
#Gets Consumer Id Number you want to create accounts for
numberOfAccounts = []
puts("Please enter a CID")
NewCID = gets.chomp()
numberOfAccounts << db.execute("select T_NBR from T_CBA where C_ID='#{NewCID}'").fetch
My array ends up like this:
[[<#BigDecimal:fc115f8,'0.8000169202 2E11',12(16)>]]
where I would like to have several different numbers like [222, 3232, 2323] etc.
I've searched online but to no avail.
DBI has probably determined that the underlying column can contain integers too large to fit in a regular int type, based on the data field. Or it may just use BigDecimal for all integer types to avoid worrying about it.
If you know that your values are all small enough to fit into a regular integer, you can convert the array to integers after you've populated it, like so:
1.9.3-p194 :014 > numberOfAccounts
=> [[#<BigDecimal:119cd90,'0.123E3',9(36)>], [#<BigDecimal:119cd18,'0.456E3',9(36)>]]
1.9.3-p194 :015 > numberOfAccounts.flatten!.collect!(&:to_i)
=> [123, 456]
1.9.3-p194 :016 > numberOfAccounts
=> [123, 456]
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