Change the output type of the json path.
This method call doesn't change the SQL in any way. This methods simply
returns a copy of this JSONPathBuilder with a new output type.
Returns an aliased version of the expression.
In addition to slapping as "the_alias" to the end of the SQL,
this method also provides strict typing:
const result = await db
.selectFrom('person')
.select(eb =>
eb('first_name', '=', 'Jennifer').as('is_jennifer')
)
.executeTakeFirstOrThrow()
// `is_jennifer: SqlBool` field exists in the result type.
console.log(result.is_jennifer)
The generated SQL (PostgreSQL):
select "first_name" = $1 as "is_jennifer"
from "person"
Access an element of a JSON array in a specific location.
Since there's no guarantee an element exists in the given array location, the resulting type is always nullable. If you're sure the element exists, you should use $assertType to narrow the type safely.
See also key to access properties of JSON objects.
db.selectFrom('person').select(eb =>
eb.ref('nicknames', '->').at(0).as('primary_nickname')
)
The generated SQL (PostgreSQL):
```sql
select "nicknames"->0 as "primary_nickname" from "person"
Combined with {@link key}:
db.selectFrom('person').select(eb =>
eb.ref('experience', '->').at(0).key('role').as('first_role')
)
The generated SQL (PostgreSQL):
select "experience"->0->'role' as "first_role" from "person"
You can use 'last' to access the last element of the array in MySQL:
db.selectFrom('person').select(eb =>
eb.ref('nicknames', '->$').at('last').as('last_nickname')
)
The generated SQL (MySQL):
select `nicknames`->'$[last]' as `last_nickname` from `person`
Or '#-1' in SQLite:
db.selectFrom('person').select(eb =>
eb.ref('nicknames', '->>$').at('#-1').as('last_nickname')
)
The generated SQL (SQLite):
select "nicknames"->>'$[#-1]' as `last_nickname` from `person`
Access a property of a JSON object.
If a field is optional, the resulting type will be nullable.
See also at to access elements of JSON arrays.
db.selectFrom('person').select(eb =>
eb.ref('address', '->').key('city').as('city')
)
The generated SQL (PostgreSQL):
select "address"->'city' as "city" from "person"
Going deeper:
db.selectFrom('person').select(eb =>
eb.ref('profile', '->$').key('website').key('url').as('website_url')
)
The generated SQL (MySQL):
select `profile`->'$.website.url' as `website_url` from `person`
Combined with at:
db.selectFrom('person').select(eb =>
eb.ref('profile', '->').key('addresses').at(0).key('city').as('city')
)
The generated SQL (PostgreSQL):
select "profile"->'addresses'->0->'city' as "city" from "person"
Creates the OperationNode that describes how to compile this expression into SQL.
If you are creating a custom expression, it's often easiest to use the sql template tag to build the node:
class SomeExpression<T> implements Expression<T> {
toOperationNode(): OperationNode {
return sql`some sql here`.toOperationNode()
}
}
Generated using TypeDoc
An expression with an
asmethod.