Restructure query arguments on custom data type with NULL value #440
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Problem:
When we send custom go type with driver.Value interface which resolve to be
nil
value, the driver fails to form the right query. Driver tries still to declare the arguments with it type.The problem self described very well in the
makeDecl
function:go-mssqldb/types.go
Line 1112 in 1eb28af
In our case scenario the database field is binary(16) nullable. We have custom field where driver.Value() returns
nil
. The query tries to declare variable as nvarchar(1) before sending it to the server, that ends up with the following error message:
mssql: Implicit conversion from data type nvarchar to binary is not allowed. Use the CONVERT function to run this query.
Solution:
Make sure we are not declaring the variables for null arguments. Instead transform query in the case that all the necessary arguments will be replaced with null value.
Same example would look like