feat(sqlite): Add json_extract and jsonb_extract functions
#4530
Conversation
KekmaTime
force-pushed
the
sqlite-json-extract
branch
from
1b8f6c4 to
56fbeb4
Compare
There was a problem hiding this comment.
Thanks for opening this PR. It seems like this method is not as straighforward to represent in diesel as we would like. I made some suggestions how we could represent it anyway. Maybe you can have a look at updating the PR? Let me know if you need more help there.
The comments about the signatures apply to the jsonb variant as well.
| /// Return type of [`json_extract(json, path)`](super::functions::json_extract()) | ||
| #[allow(non_camel_case_types)] | ||
| #[cfg(feature = "sqlite")] | ||
| pub type json_extract<J, P> = super::functions::json_extract<J, P, J, P>; |
There was a problem hiding this comment.
| pub type json_extract<J, P> = super::functions::json_extract<J, P, J, P>; | |
| pub type json_extract<J, P> = super::functions::json_extract<SqlTypeOf<J>, SqlTypeOf<P>, J, P>; |
To fix the compilation errors
| /// Return type of [`jsonb_extract(json, path)`](super::functions::jsonb_extract()) | ||
| #[allow(non_camel_case_types)] | ||
| #[cfg(feature = "sqlite")] | ||
| pub type jsonb_extract<J, P> = super::functions::jsonb_extract<J, P, J, P>; |
There was a problem hiding this comment.
| pub type jsonb_extract<J, P> = super::functions::jsonb_extract<J, P, J, P>; | |
| pub type jsonb_extract<J, P> = super::functions::jsonb_extract<SqlTypeOf<J>, SqlTypeOf<P>, J, P>; |
to fix the compilation errors
| /// If there are multiple path arguments (P1, P2, and so forth) then this routine returns SQLite text | ||
| /// which is a well-formed JSON array holding the various values. |
There was a problem hiding this comment.
This part is not possible with the function signature below. This refers to a use case where you would call json_extract(json_col, path_1, path_2) which is disallowed by the signature.
| /// If only a single path P1 is provided, then the SQL datatype of the result is NULL for a JSON null, | ||
| /// INTEGER or REAL for a JSON numeric value, an INTEGER zero for a JSON false value, an INTEGER one for a JSON true value, | ||
| /// the dequoted text for a JSON string value, and a text representation for JSON object and array values. |
There was a problem hiding this comment.
That means the signature as expressed below doesn't really match what is returned by the function. Given that is is essentially a runtime determined value I do not have any good recommendation how to make this work with diesels static checking.
I could imaging to expose just several variants of this function, so json_extract_as_text, json_extract_as_integer, json_extract_as_float and json_extract_as_json for the different return type variants and let the users chose the right one for their usecase. After all you can even convert any sql return value to any other type internally.
This PR covers implementation of json_extract() function
json_extract(X, P)- Extracts values from JSON data using path expressions.jsonb_extract(X, P)- Similar tojson_extractbut returns arrays/objects in JSONB format.