I just discovered that if you use the same name in bindparams twice in the same query, the second value clobbers the first one. For a contrived example:
db.session.query(MyTable).filter(
db.or_(
db.text("my_table.field = :value").bindparams(value=value1),
db.text("my_table.field = :value").bindparams(value=value2),
)
)
Here you would only get things with value2. value1 would not appear in the query.
Is there a general purpose way to fix this?
Btw, db.text() bits in my real query access nested jsonb properties, so please don't answer telling me to just use the column objects in this query in place of db.text().
Related
The SQLite JSON1 extension has some really neat capabilities. However, I have not been able to figure out how I can update or insert individual JSON attribute values.
Here is an example
CREATE TABLE keywords
(
id INTEGER PRIMARY KEY,
lang INTEGER NOT NULL,
kwd TEXT NOT NULL,
locs TEXT NOT NULL DEFAULT '{}'
);
CREATE INDEX kwd ON keywords(lang,kwd);
I am using this table to store keyword searches and recording the locations from which the search was ininitated in the object locs. A sample entry in this database table would be like the one shown below
id:1,lang:1,kwd:'stackoverflow',locs:'{"1":1,"2":1,"5":1}'
The location object attributes here are indices to the actual locations stored elsewhere.
Now imagine the following scenarios
A search for stackoverflow is initiated from location index "2". In this case I simply want to increment the value at that index so that after the operation the corresponding row reads
id:1,lang:1,kwd:'stackoverflow',locs:'{"1":1,"2":2,"5":1}'
A search for stackoverflow is initiated from a previously unknown location index "7" in which case the corresponding row after the update would have to read
id:1,lang:1,kwd:'stackoverflow',locs:'{"1":1,"2":1,"5":1,"7":1}'
It is not clear to me that this can in fact be done. I tried something along the lines of
UPDATE keywords json_set(locs,'$.2','2') WHERE kwd = 'stackoverflow';
which gave the error message error near json_set. I'd be most obliged to anyone who might be able to tell me how/whether this should/can be done.
It is not necessary to create such complicated SQL with subqueries to do this.
The SQL below would solve your needs.
UPDATE keywords
SET locs = json_set(locs,'$.7', IFNULL(json_extract(locs, '$.7'), 0) + 1)
WHERE kwd = 'stackoverflow';
I know this is old, but it's like the first link when searching, it deserves a better solution.
I could have just deleted this question but given that the SQLite JSON1 extension appears to be relatively poorly understood I felt it would be more useful to provide an answer here for the benefit of others. What I have set out to do here is possible but the SQL syntax is rather more convoluted.
UPDATE keywords set locs =
(select json_set(json(keywords.locs),'$.**N**',
ifnull(
(select json_extract(keywords.locs,'$.**N**') from keywords where id = '1'),
0)
+ 1)
from keywords where id = '1')
where id = '1';
will accomplish both of the updates I have described in my original question above. Given how complicated this looks a few explanations are in order
The UPDATE keywords part does the actual updating, but it needs to know what to updatte
The SELECT json_set part is where we establish the value to be updated
If the relevant value does not exsit in the first place we do not want to do a + 1 on a null value so we do an IFNULL TEST
The WHERE id = bits ensure that we target the right row
Having now worked with JSON1 in SQLite for a while I have a tip to share with others going down the same road. It is easy to waste your time writing extremely convoluted and hard to maintain SQL in an effort to perform in-place JSON manipulation. Consider using SQLite in memory tables - CREATE TEMP TABLE... to store intermediate results and write a sequence of SQL statements instead. This makes the code a whole lot eaiser to understand and to maintain.
So, I am trying to execute a query using ArcGIS API, but it should match any Json queries. I am kind of new to this query format, so I am pretty sure I must be missing something, but I can't figure out what it is.
This page allows for testing queries on the database before I actually implement them in my code. Features in this database have several fields, including OBJECTID and Identificatie. I would like to, for example, select the feature where Identificatie = 1. If I enter this in the Where field though (Identificatie = 1) an error Failed to execute appears. This happens for every field, except for OBJECTID. Querying where OBJECTID = 1 returns the correct results. I am obviously doing something wrong, but I don't get it why OBJECTID does work here. A brief explanation (or a link to a page documenting queries for JSON, which I haven't found), would be appreciated!
Identificatie, along with most other fields in the service you're using, is a string field. Therefore, you need to use single quotes in your WHERE clause:
Identificatie = '1'
Or to get one that actually exists:
Identificatie = '1714100000729432'
OBJECTID = 1 works without quotes because it's a numeric field.
Here's a link to the correct query. And here's a link to the query with all output fields included.
I have a PostgreSQL table with a JSON column, and I'm trying to get a list of all the distinct keys in that column. I created a query to do this:
SELECT DISTINCT json_object_keys(j) FROM t;
Where t is the table and j is the JSON column. This worked on a small set of data correctly, it would list all the keys that exist in j, without repeating them. However, after adding a lot more data, it doesn't work anymore, giving the error:
ERROR: cannot call json_object_keys on a scalar
I'm not sure exactly why this is happening. By just limiting the query to certain rows one at a time, I found one that causes the error. In that row, j is null. However, calling SELECT json_object_keys(null); does not cause this error, while calling SELECT json_object_keys(j) FROM t WHERE id=12; does, and j in this row is just null. I'm not really sure where to go from here.
So I guess my question is what could be causing this, and how can I either work around it or prevent it from happening?
Running PostgreSQL 9.3.9
Edit: Ok, I may have posted this a little preemptively. I figured out that j in the problematic row isn't null, it's 'null'::json, which wasn't clear from just selecting the row. This does cause the scalar error, so now I just have to figure out a way to select the rows where j isn't 'null'::json.
I tried this query, to filter out the 'null'::json values with this query:
SELECT DISTINCT json_object_keys(j) from t WHERE j <> 'null'::json;
However, apparently there is no json <> json operator, so I had to cast it to text and compare.
SELECT DISTINCT json_object_keys(j) from t WHERE j::TEXT <> 'null';
This works! I'm not a Postgres expert though, so this may not be the most effecient way of doing this check.
before i use alias for table i get the error:
: Integrity constraint violation: 1052 Column 'id' in field list is ambiguous
Then i used aliases and i get this error:
unknown index a
I am trying to get a list of category name ( dependant to a translation) and the associated category id which is unique. Since i need to put them in a select, i see that i should use the lists.
$categorie= DB::table('cat as a')
->join('campo_cat as c','c.id_cat','=','a.id')
->join('campo as d','d.id','=','c.id_campo')
->join('cat_nome as nome','nome.id_cat','=','a.id')
->join('lingua','nome.id_lingua','=','lingua.id')
->where('lingua.lingua','=','it-IT')
->groupby('nome.nome')
->lists('nome.nome','a.id');
The best way to debug your query is to look at the raw query Laravel generates and trying to run this raw query in your favorite SQL tool (Navicat, MySQL cli tool...), so you can dump it to log using:
DB::listen(function($sql, $bindings, $time) {
Log::info($sql);
Log::info($bindings);
});
Doing that with yours I could see at least one problem:
->where('lingua.lingua','=','it-IT')
Must be changed to
->where('lingua.lingua','=',"'it-IT'")
As #jmail said, you didn't really describe the problem very well, just what you ended up doing to get around (part of) it. However, if I read your question right you're saying that originally you did it without all the aliases you got the 'ambiguous' error.
So let me explain that first: this would happen, because there are many parts of that query that use id rather than a qualified table`.`id.
if you think about it, without aliases you query looks a bit like this: SELECT * FROM `cat` JOIN `campo_cat` ON `id_cat` = `id` JOIN `campo` ON `id` = `id_campo`; and suddenly, MySQL doesn't know to which table all these id columns refer. So to get around that all you need to do is namespace your fields (i.e. use ... JOIN `campo` ON `campo`.`id` = `campo_cat`.`id_campo`...). In your case you've gone one step further and aliased your tables. This certianly makes the query a little simpler, though you don't need to actually do it.
So on to your next issue - this will be a Laravel error. And presumably happening because your key column from lists($valueColumn, $keyColumn) isn't found in the results. This is because you're referring to the cat.id column (okay in your aliased case a.id) in part of the code that's no longer in MySQL - the lists() method is actually run in PHP after Laravel gets the results from the database. As such, there's no such column called a.id. It's likely it'll be called id, but because you don't request it specifically, you may find that the ambiguous issue is back. My suggestion would be to select it specifically and alias the column. Try something like the below:
$categories = DB::table('cat as a')
->join('campo_cat as c','c.id_cat','=','a.id')
->join('campo as d','d.id','=','c.id_campo')
->join('cat_nome as nome','nome.id_cat','=','a.id')
->join('lingua','nome.id_lingua','=','lingua.id')
->where('lingua.lingua','=','it-IT')
->groupby('nome.nome')
->select('nome.nome as nome_nome','a.id as a_id') // here we alias `.id as a_id
->lists('nome_nome','a_id'); // here we refer to the actual columns
It may not work perfectly (I don't use ->select() so don't know whether you pass an array or multiple parameters, also you may need DB::raw() wrapping each one in order to do the aliasing) but hopefully you get my meaning and can get it working.
I am working on a problem where I need to add an OR clause to a set of existing conditions. The current conditions are built in a hash in a method and at the end, they are used in the where clause. Here is a simplified example:
...
conds.merge!({:users => {:archived => false}})
Model.where(conds)
I am trying to add an OR clause to the current set of conditions so it would be something like '(conditions) OR new_condition'. I'd like to add the OR statement without converting each addition to the conds hash into a string. That would be my last option. I was hoping someone has done something like this before (without using Arel). I seem to recall in Rails 2 there was a way to parse a conditions hash using a method from the model (something like Model.some_method(conds) would produce the where clause string. Maybe that would be a good option to just add the OR clause on to that string. Any ideas are appreciated. Thank you for your help!
I found a way to do what I needed. Instead of changing all of the conditions that I am building, I am parsing the conditions to SQL using sanitize_sql_for_conditions. This is a private method in ActiveRecord, so I had to put a method on the model to allow me to access it. Here is my model method:
def self.convert_conditions_hash_to_sql(conditions)
self.sanitize_sql_for_conditions(conditions)
end
So, once I convert my conditions to text, I can add my OR clause (along with the appropriate parentheses) to the end of the original conditions. So, it would go something like this:
Model.where('(?) OR (model.type = ? AND model.id IN(?))', Model.convert_conditions_hash_to_sql(conds), model_type, model_id_array)