I have a table in a postgresql database with one field with json format.
It's look like this :
[
{
"transition": "transition1",
"from": "step1",
"to": "step2",
"date": {
"date": "2021-01-30 15:34:06.840859"
}
},
{
"transition": "transition2",
"from": "step2",
"to": "step3",
"date": {
"date": "2021-01-30 16:52:00.412208"
}
}
]
I want to have a new column with the date of transition1.
I tried a lot of things but I can't figure out how to extract this date, I can't use the index because the number of transition is not fixed, some user could have 3 and other more than 10.
You need to iterate over all array elements to find the correct one:
select (select (item -> 'date' ->> 'date')::timestamp
from jsonb_array_elements(jsonb_column) as x(item)
where item ->> 'transition' = 'transition1') as transition_date
from the_table
;
If you column is defined as json rather than jsonb (which it should be) you need to use json_array_elements() instead.
Related
For the given input JSON:
{
"person": {
"name": "John",
"age": 25
},
"status": {
"title": "assigned",
"type": 3
}
}
I need to build a string query that I could use to answer if the given JSON matches it or not. For example if the given person's name is "John" and his age is in the range of 20..30 and his status is not 4.
I need the query to be presented as a string and a commonly known library that can run it. I need it on multiple platforms (iOS, Android, Xamarin). I've tried JSON Path and JSON schemas, but didn't really figure out if it's able to achieve that with them. JSON Path seems to be specified on finding a single value in the JSON by a certain condition and JSON Schema mostly checks for the data structure and types.
Ok, found the solution. If I format the whole input object as a single-element array like that:
[
{
"person": {
"name": "John",
"age": 25
},
"status": {
"title": "assigned",
"type": 3
}
}
]
That will allow me to use JSON Path expressions:
$[?(#.person.name == 'John' && #.person.age >= 20 && #.status.type != 4)]
Basically if it doesn't match there won't be a result.
In my DB I have a column storing JSON. The JSON looks like this:
{
"views": [
{
"id": "1",
"sections": [
{
"id": "1",
"isToggleActive": false,
"components": [
{
"id": "1",
"values": [
"02/24/2021"
]
},
{
"id": "2",
"values": []
},
{
"id": "3",
"values": [
"5393",
"02/26/2021 - Weekly"
]
},
{
"id": "5",
"values": [
""
]
}
]
}
]
}
]
}
I want to create a migration script that will extract a value from this JSON and store them in its own column.
In the JSON above, in that components array, I want to extract the second value from the component with an ID of "3" (among other things, but this is a good example). So, I want to extract the value "02/26/2021 - Weekly" to store in its own column.
I was looking at the JSON_VALUE docs, but I only see examples for specifing indexes for the json properties. I can't figure out what kind of json path I'd need. Is this even possible to do with JSON_VALUE?
EDIT: To clarify, the views and sections components can have static array indexes, so I can use views[0].sections[0] for them. Currently, this is all I have with my SQL query:
SELECT
*
FROM OPENJSON(#jsonInfo, '$.views[0].sections[0]')
You need to use OPENJSON to break out the inner array, then filter it with a WHERE and finally select the correct value with JSON_VALUE
SELECT
JSON_VALUE(components.value, '$.values[1]')
FROM OPENJSON (#jsonInfo, '$.views[0].sections[0].components') components
WHERE JSON_VALUE(components.value, '$.id') = '3'
In PostgreSQL database I have a json column called json. Data inside look like below:
{
"Version": "0.0.0.1",
"Items": [
{
"Id": "40000000-0000-0000-0000-000000141146",
"Name": "apple",
"Score": 64,
"Value": 1430000
},
{
"Id": "40000000-0000-0000-0000-000000141147",
"Name": "grapefruit",
"Score": 58,
"Value": 1190000
},
{
"Id": "40000000-0000-0000-0000-000000141148",
"Name": "mango",
"Score": 41,
"Value": 170000
}
]
}
What I would like to do is retrieving all Score data from Items elements.
I was trying to use SQL code:
select
substring(json ->> 'Items' from '"Score": (\d*),') as score
from vegetables;
However that returns just the score from first element instead of 3. I was trying to use '\g' flag which supposed to find all results globally, but the code was not working.
Could anyone advise how to do that properly? Thanks in advance!
Considering that the data type of json field is jsonb then no need to use substring or regex, simply lateral join with jsonb_array_elements will do the required things for you. Try below query.
select x->>'Score' "Score" from vegetables
cross join lateral jsonb_array_elements(json->'Items') x
DEMO
I have a table with a data_type of json that I need to query one of the properties inside of it.
This is what the data in the column looks like:
{
"id": 7008,
"access_links": [
{
"product_code": "PRODUCT-1",
"link": "https://some.url"
},
{
"product_code": "PRODUCT-2",
"link": "https://someOther.url"
}
],
"library_id": "2d1203db-75b3-43a5-947c-8555b48371db"
}
I need to be able to pull out and filter by the product_code nested inside of the access_links.
I can get one layer deep by using this query:
SELECT
courses.course_metadata -> 'access_links' as access_links
FROM
courses
This seems to get me into the column, but I can't query any further.
The output I receive from the query looks like:
[{"product_code":"PRODUCT-1","link":"https://some.url"},{"product_code":"PRODUCT-2","link":"https://someOther.url"}]
I've tried using the ->> and #>> operators, but they both complain about the array not starting with a {. Also worth noting that the column is a data type of JSON not JSONB, so the #> operator doesn't work.
What am I missing here?
Does this help?
select
json_array_elements (x->'access_links')->'product_code' as product_code
from
(select '{
"id": 7008,
"access_links": [
{
"product_code": "PRODUCT-1",
"link": "https://some.url"
},
{
"product_code": "PRODUCT-2",
"link": "https://someOther.url"
}
],
"library_id": "2d1203db-75b3-43a5-947c-8555b48371db"
}'::json x
) as v
;
product_code
"PRODUCT-1"
"PRODUCT-2"
I have a json column in a postgres table.
The column contains the following json data:
{
"data": {
"id": "1234",
"sites": [
{
"site": {
"code": "1",
"display": "Site1"
}
},
{
"site": {
"code": "2",
"display": "Site2"
},
"externalSite": true
},
{
"site": {
"code": "3",
"display": "Site3"
}
}
]
}
}
I need to create an update query that adds another attribute ('newAttribute' in the sample below) to all array items that have '"externalSite": true', so, after running the update query the second array element will be:
{
"site": {
"code": "2",
"display": "Site2"
},
"externalSite": true,
"newAttribute": true
}
The following query returns the array elements that need to be updated:
select * from myTable, jsonb_array_elements(data -> 'sites') sites
where sites ->'externalSite' = 'true'
What is the syntax of the update query?
Thanks
Kobi
Assuming your table is called test and your column is called data, you can update it like so:
UPDATE test SET data =
(select jsonb_set(data::jsonb, '{"data","sites"}', sites)
FROM test
CROSS JOIN LATERAL (
SELECT jsonb_agg(CASE WHEN site ? 'externalSite' THEN site || '{"newAttribute":"true"}'::jsonb
ELSE site
END) AS sites
FROM jsonb_array_elements( (data#>'{"data","sites"}')::jsonb ) as ja(site)
) as sub
);
Note that I cast the data to jsonb data as there are more functions and operators available for manipulating jsonb than plain json.
You can run the SELECT statement alone to see what it is doing, but the basic idea is to re-create the sites object by expanding it with jsonb_array_elements and adding the newAttribute attribute if externalSite exists.
This array is then aggregated with jsonb_agg and, finally, in the outer select, the sites object is replaced entirely with this newly computed version.