Cast to ARRAY Types

ARRAY type is used to store and process array data, which can contain various basic element types such as integers, strings, etc., and can also nest other complex types.

Cast to ARRAY

FROM String

Behavior Change

Before version 4.0, parsing would fail for empty strings between delimiters, for example "[,,]" would return NULL. Starting from version 4.0, "[,,]" will return [null, null, null] in non-strict mode and report an error in strict mode.

Strict Mode

BNF Definition

<array>          ::= "[" <array-content>? "]" | <empty-array> 

<empty-array> ::= "[]"

<array-content>  ::=  <data-token>(<collection-delim> <data-token>)*

<data-token>    ::= <whitespace>* "\"" <inner-sequence> "\"" <whitespace>*
                   | <whitespace>* "'" <inner-sequence> "'" <whitespace>*
                   | <whitespace>* <inner-sequence> <whitespace>*

<inner-sequence>    ::= .*

<collection-delim>  ::= "," 

Rule Description

1. The textual representation of an array must begin with a left bracket [ and end with a right bracket ].
2. Empty arrays are directly represented as [].
3. Elements within the array are separated by commas.
4. Whitespace is allowed before and after elements within the array.
5. Array elements can be enclosed in matching single quotes (') or double quotes (").
6. Elements can use "null" to represent a null value.
7. During parsing, parts that match <data-token> continue to apply the parsing rules of the target type T.

If the above rules are not met, or if the elements do not meet the requirements of the corresponding type, an error is reported.

Examples

Input String	Conversion Result	Comment
'[]'	[]	Valid empty array
' []'	Error	Array does not start with a bracket, parsing fails
'[ ]'	Error	Array has one element, a string of spaces; space string fails to parse as int
"[ 123, 123]"	Cast to Array<int>: [123, 123]	Valid array
'[ " 123 " , "456 "]'	Cast to Array<int>: [123, 456]	Valid array
'[ 123 , "456" ]'	Cast to Array<int>: [123, 456]	Valid array
'[ [] ]'	Cast to Array<Array<int>>: [[]]	The first array's internal element is ' [] ', which becomes a valid array after trimming
'[ null ,123]'	Cast to Array<int>: [null, 123]	Valid array containing null
'[ "null" ,123]'	Error	String "null" cannot be converted to int type

Note: Ensure that elements between commas contain valid content, otherwise parsing will fail.

Non-Strict Mode

BNF Definition

<array>          ::= "[" <array-content>? "]" | <empty-array> 

<empty-array> ::= "[]"

<array-content>  ::=  <data-token>(<collection-delim> <data-token>)*

<data-token>    ::= <whitespace>* "\"" <inner-sequence> "\"" <whitespace>*
                   | <whitespace>* "'" <inner-sequence> "'" <whitespace>*
                   | <whitespace>* <inner-sequence> <whitespace>*

<inner-sequence>    ::= .*

<collection-delim>  ::= "," 

Rule Description

1. The textual representation of an array must begin with a left bracket [ and end with a right bracket ].
2. Empty arrays are directly represented as [].
3. Elements within the array are separated by commas.
4. Whitespace is allowed before and after elements within the array.
5. Array elements can be enclosed in matching single quotes (') or double quotes (").
6. Elements can use "null" to represent a null value.
7. During parsing, parts that match <data-token> continue to apply the parsing rules of the target type T.

If the array format does not meet the BNF format above, NULL is returned. If elements do not meet the requirements of the corresponding type, the corresponding element position is set to null.

Examples

Input String	Conversion Result	Comment
'[]'	[]	Valid empty array
' []'	NULL	Array does not start with a bracket, parsing fails
'[ ]'	[null]	Array has one element, a string of spaces; space string fails to parse as int
"[ 123, 123]"	Cast to Array<int>: [123, 123]	Valid array
'[ " 123 " , "456 "]'	Cast to Array<int>: [123, 456]	Valid array
'[ 123 , "456" ]'	Cast to Array<int>: [123, 456]	Valid array
'[ [] ]'	Cast to Array<Array<int>>: [[]]	The first array's internal element is ' [] ', which becomes a valid array after trimming
'[ null ,123]'	Cast to Array<int>: [null, 123]	Valid array containing null
'[ "null" ,123]'	Cast to Array<int>: [null, 123]	String "null" cannot be converted to int type, converted to null

FROM Array<Other Type>

Strict Mode

Rule Description

For each element in the Array, a Cast from Other Type To Type is performed. The Cast is also in strict mode.

Examples

Input Array	Conversion Result	Comment
["123", "456"]	Cast to Array<int>: [123, 456]	"123" and "456" can be converted to Int
["abc", "123"]	Error	"abc" cannot be converted to Int
[null, "123"]	Cast to Array<int>: [null, 123]	The Cast result of null is still null

Non-Strict Mode

Rule Description

For each element in the Array, a Cast from Other Type To Type is performed. The Cast is also in non-strict mode.

Examples

Input Array	Conversion Result	Comment
["123", "456"]	Cast to Array<int>: [123, 456]	"123" and "456" can be converted to Int
["abc", "123"]	Cast to Array<int>: [null, 123]	"abc" cannot be converted to Int, converted to null
[null, "123"]	Cast to Array<int>: [null, 123]	The Cast result of null is still null