Add support for check constraints. #270
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SackCastellon
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Check constraint can be used with multiple columns (https://www.w3schools.com/sql/sql_check.asp), do you mind to support it too? |
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Check constraint with multiple columns are already supported. val positive = integer("positive").check { it greaterEq 0 }
val negative = integer("negative").check("subZero") { it less 0 }Or just one check in the last column involving all the previous columns: val positive = integer("positive")
val negative = integer("negative").check("multiColumn") { (it less 0) and (positive greaterEq 0) }Both are equivalent. Is this what you meant? |
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Not exactly, I mean that you may want to define complex Maybe there should be separate |
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Okay, I'll try to implement it. |
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That the best way that I found to implement it |
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Sorry, but I'll be able to verify PR only on weekends. |
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| override fun createStatement(): List<String> { | ||
| if (currentDialect is MysqlDialect) throw UnsupportedOperationException("Check constraints are not currently supported by MySQL") |
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I guess it's better to log warn or error, because MySQL parses CHECK expression, but ignore it.
If you work with different databases and use same Exposed classes then you will have problem running it on MySQL.
| * @param op The expression that the value of this column must satisfy | ||
| */ | ||
| fun <T> Column<T>.check(name: String = "", op: SqlExpressionBuilder.(Column<T>) -> Op<Boolean>) = apply { | ||
| table.checkConstraints.add(name to SqlExpressionBuilder.op(this)) |
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Maybe it's worth to check that constraint with the same name already in checkConstraints list?
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Yes, you are right. I just checked and SQLite is the only database, among MySQL, H2 and Postgres, that supports multiple constraints with the same name.
I'll add the necessary code to check for repeated names.
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I am also considering to .trim() the name before it is added to the list. What do you think @Tapac?
Also, empty names will be added even if there are constraints with empty names already, so an automatic name is generated by the database.
- Warning shown when trying to create a CHECK constraint in MySQL - Constraint with names that were already added are ignored and a warning is shown - White spaces are now trimmed from constraint names - Improved tests
| @@ -76,17 +76,17 @@ data class CheckConstraint(val tableName: String, val checkName: String, val che | |||
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| override fun createStatement(): List<String> { | |||
| if (currentDialect is MysqlDialect) throw UnsupportedOperationException("Check constraints are not currently supported by MySQL") | |||
| if (currentDialect is MysqlDialect) exposedLogger.warn("CHECK constraints are not currently supported by MySQL") | |||
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One more "idea": why not to return an empty list in a case when the database doesn't support constraints? With warn logging ofc.
Here and in dropStatements(). And you can remove any checks in modifyStatements().
…ame if it wasn't provided b/c Oracle doesn't support CHECK without name
This is a first implementation of the support for check constraints, based on the Issue #268
A test has been created to test this new functionality:
DDLTests.testCheckConstraint(). It has been tested to work with PostgreSQL, SQLite and H2.