Postgres json select not ignoring quotes - postgresql

I have the following table and setup
create table test (
id serial primary key,
name text not null,
meta json
);
insert into test (name, meta) values ('demo1', '{"name" : "Hello"}')
However, when I run this query, this is the result
select * from test;
id | name | meta
----+-------+--------------------
1 | demo1 | {"name" : "Hello"}
(1 row)
but
select * from test where meta->'name' = 'Hello';
ERROR: operator does not exist: json = unknown
LINE 1: select * from test where meta->'name' = 'Hello';
^
HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts.
-
select * from test where cast(meta->'name' as text) = 'Hello';
id | name | meta
----+------+------
(0 rows)
and this works
select * from test where cast(meta->'name' as text) = '"Hello"';
id | name | meta
----+-------+--------------------
1 | demo1 | {"name" : "Hello"}
(1 row)
Can anyone tell me what the relevance of this quote is and why it's not doing a simple string search/comparison? Alternatively, does this have something to do with the casting?

That's because the -> gets a field not a value, so you need to add the cast to say to postgresql which data type you are after.
So to run your query like you want you need to use the ->> which gets the json element as text see it here on the docs JSON Functions and Operators
So your query should looks like:
select *
from test
where meta->>'name' = 'Hello';
See it working here: http://sqlfiddle.com/#!15/bf866/8

Related

How to update JSONB column with value coming from another table column in PostgreSQL

I have a source table, which lists like below:
public.source
Id | part_no | category
1 | 01270-4 | Landscape
2 | 01102-3 | Sports
Then, I have target table with jsonb column (combinations) , which list like below;
public.target
Id | part_no | combinations
7 | 01270-4 | {"subject":""}
8 | 01102-3 | {"subject":""}
My problem is - how I can update the target table with jsonb column (combinations) with the values coming from source table using the part_no column?
Output like:
Id | part_no | combinations
7 | 01270-4 | {"subject":"Landscape"}
8 | 01102-3 | {"subject":"Sports"}
I tried below but giving error:
UPDATE public.target t
SET combinations = jsonb_set(combinations,'{subject}','s.category',false)
FROM public.source s
WHERE s.part_no = t.part_no;
ERROR: invalid input syntax for type json
LINE 2: SET combinations = jsonb_set(combinations,'{subject}', 's.categor...
^
DETAIL: Token "s" is invalid.
CONTEXT: JSON data, line 1: s...
SQL state: 22P02
Character: 77
You should use to_jsonb function to convert s.category to JSON
Demo
UPDATE public.target t
SET combinations = jsonb_set(combinations,'{subject}',to_jsonb(s.category),false)
FROM public.source s
WHERE s.part_no = t.part_no
Or you can use sample structure for join and update two JSON field:
Demo
UPDATE public.target t
SET combinations = combinations || jsonb_build_object('subject', s.category)
FROM public.source s
WHERE s.part_no = t.part_no

Get cutted JSON in query

I have a column in db which constains JSON values like:
{"key-1": "val-1", "key-2": "val-2", "key-3": "val-3"}
By query like..
SELECT column->>'key-1' FROM table;
I can get my val-1.
Is there a way to get value with key as JSON in sql query from already existed JSON value?
I want to get result like:
{"key-1": "val-1"}
from
{"key-1": "val-1", "key-2": "val-2", "key-3": "val-3"}
using sql query.
Use ampersand operator, &, e.g.,
Live test: https://www.db-fiddle.com/f/9izCEH75JhwVDvsGvsZomG/0
with the_table as
(
select '{"key-1": "val-1", "key-2": "val-2", "key-3": "val-3"}'::jsonb as d
)
select d & 'key-1' as j from the_table
Output:
| j |
| ----------------- |
| {"key-1":"val-1"} |
Just kidding :) Create a function that extracts the desired key value pair, and then create your own user-defined operator for it.
create or replace function extract_one_jsonb(j jsonb, key text)
returns jsonb
as
$$
select jsonb_build_object(key, j->key)
$$ language sql;
create operator & (
leftarg = jsonb,
rightarg = text,
procedure = extract_one_jsonb
);
Of course you can just use a function, or if creating a user-defined operator is not an option:
with the_table as
(
select '{"key-1": "val-1", "key-2": "val-2", "key-3": "val-3"}'::jsonb as d
)
select extract_one_jsonb(d, 'key-1') as j from the_table
Output:
| j |
| ----------------- |
| {"key-1":"val-1"} |
If extracting a key value pair from jsonb is being done many times, it's desirable to give an operator for it, e.g., &. Postgres is pretty flexible when you want to create your own operator, this can be created too: ->>>.
Live test: https://www.db-fiddle.com/f/9izCEH75JhwVDvsGvsZomG/1
create operator ->>> (
leftarg = jsonb,
rightarg = text,
procedure = extract_one_jsonb
);
Output:
| j |
| ----------------- |
| {"key-1":"val-1"} |
->> is already used by Postgres: https://www.postgresql.org/docs/11/functions-json.html
You can create '->>>' instead. ->>> looks more like an extractor operator than ampersand &. Besides it looks good even you stick it to the source field (that is without spaces)
with the_table as
(
select '{"key-1": "val-1", "key-2": "val-2", "key-3": "val-3"}'::jsonb as d
)
select d->>>'key-1' as j from the_table
Tried the following, it works too, looks like a scissor (for cutting): %>
select d%>'key-1' as j from the_table
The only thing I can think of is to get the key/value pair and assemble that back into a single JSON value:
select jsonb_build_object(j.k, j.v)
from the_table t, jsonb_each(t.json_col) as j(k,v)
where j.k = 'key-1'
and ... more conditions ...;
Online example: https://rextester.com/VGSX43955

How to push data into a "JSON" data type column in Postgresql

I have the following POSTGRESQL table
id | name | email | weightsovertime | joined
20 | Le | le#gmail.com | [] | 2018-06-09 03:17:56.718
I would like to know how to push data (JSON object or just object) into the weightsovertime array.
And since I am making a back-end server, I would like to know the KnexJS query that does this.
I tried the following syntax but it does not work
update tableName set weightsovertime = array_append(weightsovertime,{"weight":55,"date":"2/3/96"}) where id = 20;
Thank you
For anyone who happens to land on this question, the solution using Knex.js is:
knex('table')
.where('id', id)
.update({
arrayColumn: knex.raw(`arrayColumn || ?::jsonb`, JSON.stringify(arrayToAppend))
})
This will produce a query like:
update tableName
set weightsovertime = arrayColumn || $1::json
where id = 20;
Where $1 will be replaced by the value of JSON.stringfy(arrayToAppend). Note that this conversion is obligatory because of a limitation of the Postegre drive
array_append is for native arrays - a JSON array inside a jsonb column is something different.
Assuming your weightsovertime is a jsonb (or json) you have to use the concatenation operator : ||
e.g:
update the_table
set weitghtsovertime = weightsovertime||'[{"weight": 55, "date": "1996-03-02"}]'
where id = 20;
Online example: http://rextester.com/XBA24609

Inserting values into multiple columns by splitting a string in PostgreSQL

I have the following heap of text:
"BundleSize,155648,DynamicSize,204800,Identifier,com.URLConnectionSample,Name,
URLConnectionSample,ShortVersion,1.0,Version,1.0,BundleSize,155648,DynamicSize,
16384,Identifier,com.IdentifierForVendor3,Name,IdentifierForVendor3,ShortVersion,
1.0,Version,1.0,".
What I'd like to do is extract data from this in the following manner:
BundleSize:155648
DynamicSize:204800
Identifier:com.URLConnectionSample
Name:URLConnectionSample
ShortVersion:1.0
Version:1.0
BundleSize:155648
DynamicSize:16384
Identifier:com.IdentifierForVendor3
Name:IdentifierForVendor3
ShortVersion:1.0
Version:1.0
All tips and suggestions are welcome.
It isn't quite clear what do you need to do with this data. If you really need to process it entirely in the database (looks like the task for your favorite scripting language instead), one option is to use hstore.
Converting records one by one is easy:
Assuming
%s =
BundleSize,155648,DynamicSize,204800,Identifier,com.URLConnectionSample,Name,URLConnectionSample,ShortVersion,1.0,Version,1.0
SELECT * FROM each(hstore(string_to_array(%s, ',')));
Output:
key | value
--------------+-------------------------
Name | URLConnectionSample
Version | 1.0
BundleSize | 155648
Identifier | com.URLConnectionSample
DynamicSize | 204800
ShortVersion | 1.0
If you have table with columns exactly matching field names (note the quotes, populate_record is case-sensitive to key names):
CREATE TABLE data (
"BundleSize" integer, "DynamicSize" integer, "Identifier" text,
"Name" text, "ShortVersion" text, "Version" text);
You can insert hstore records into it like this:
INSERT INTO data SELECT * FROM
populate_record(NULL::data, hstore(string_to_array(%s, ',')));
Things get more complicated if you have comma-separated values for more than one record.
%s = BundleSize,155648,DynamicSize,204800,Identifier,com.URLConnectionSample,Name,URLConnectionSample,ShortVersion,1.0,Version,1.0,BundleSize,155648,DynamicSize,16384,Identifier,com.IdentifierForVendor3,Name,IdentifierForVendor3,ShortVersion,1.0,Version,1.0,
You need to break up an array into chunks of number_of_fields * 2 = 12 elements first.
SELECT hstore(row) FROM (
SELECT array_agg(str) AS row FROM (
SELECT str, row_number() OVER () AS i FROM
unnest(string_to_array(%s, ',')) AS str
) AS str_sub
GROUP BY (i - 1) / 12) AS row_sub
WHERE array_length(row, 1) = 12;
Output:
"Name"=>"URLConnectionSample", "Version"=>"1.0", "BundleSize"=>"155648", "Identifier"=>"com.URLConnectionSample", "DynamicSize"=>"204800", "ShortVersion"=>"1.0"
"Name"=>"IdentifierForVendor3", "Version"=>"1.0", "BundleSize"=>"155648", "Identifier"=>"com.IdentifierForVendor3", "DynamicSize"=>"16384", "ShortVersion"=>"1.0"
And inserting this into the aforementioned table:
INSERT INTO data SELECT (populate_record(NULL::data, hstore(row))).* FROM ...
the rest of the query is the same.

Filter an ID Column against a range of values

I have the following SQL:
SELECT ',' + LTRIM(RTRIM(CAST(vessel_is_id as CHAR(2)))) + ',' AS 'Id'
FROM Vessels
WHERE ',' + LTRIM(RTRIM(CAST(vessel_is_id as varCHAR(2)))) + ',' IN (',1,2,3,4,5,6,')
Basically, I want to filter the vessel_is_id against a variable list of integer values (which is passed in as a varchar into the stored proc). Now, the above SQL does not work. I do have rows in the table with a `vessel__is_id' of 1, but they are not returned.
Can someone suggest a better approach to this for me? Or, if the above is OK
EDIT:
Sample data
| vessel_is_id |
| ------------ |
| 1 |
| 2 |
| 5 |
| 3 |
| 1 |
| 1 |
So I want to returned all of the above where vessel_is_id is in a variable filter i.e. '1,3' - which should return 4 records.
Cheers.
Jas.
IF OBJECT_ID(N'dbo.fn_ArrayToTable',N'FN') IS NOT NULL
DROP FUNCTION [dbo].[fn_ArrayToTable]
GO
CREATE FUNCTION [dbo].fn_ArrayToTable (#array VARCHAR(MAX))
-- =============================================
-- Author: Dan Andrews
-- Create date: 04/11/11
-- Description: String to Tabled-Valued Function
--
-- =============================================
RETURNS #output TABLE (data VARCHAR(256))
AS
BEGIN
DECLARE #pointer INT
SET #pointer = CHARINDEX(',', #array)
WHILE #pointer != 0
BEGIN
INSERT INTO #output
SELECT RTRIM(LTRIM(LEFT(#array,#pointer-1)))
SELECT #array = RIGHT(#array, LEN(#array)-#pointer),
#pointer = CHARINDEX(',', #array)
END
RETURN
END
Which you may apply like:
SELECT * FROM dbo.fn_ArrayToTable('2,3,4,5,2,2')
and in your case:
SELECT LTRIM(RTRIM(CAST(vessel_is_id AS CHAR(2)))) AS 'Id'
FROM Vessels
WHERE LTRIM(RTRIM(CAST(vessel_is_id AS VARCHAR(2)))) IN (SELECT data FROM dbo.fn_ArrayToTable('1,2,3,4,5,6')
Since Sql server doesn't have an Array you may want to consider passing in a set of values as an XML type. You can then turn the XML type into a relation and join on it. Drawing on the time-tested pubs database for example. Of course you're client may or may not have an easy time generating the XML for the parameter value, but this approach is safe from sql-injection which most "comma seperated" value approaches are not.
declare #stateSelector xml
set #stateSelector = '<values>
<value>or</value>
<value>ut</value>
<value>tn</value>
</values>'
select * from authors
where state in ( select c.value('.', 'varchar(2)') from #stateSelector.nodes('//value') as t(c))