GitHub user finlaydotb closed a discussion: How may I construct a value of vec
of vecs for a record batch?
I can create column of type "UTF8" as follows
```
let schema = Arc::new(Schema::new(vec![
Field::new("id", DataType::Int32, false),
Field::new("payload", DataType::Utf8, false),
]));
let vec_of_strings: Vec<String> = vec!["one".to_string(),
"two".to_string()];
let batch = RecordBatch::try_new(
schema,
vec![
Arc::new(Int32Array::from_slice([1, 2])),
Arc::new(StringArray::from(vec_of_strings)),
],
)?;
ctx.register_batch("demo", batch)?;
```
Executing a query against this, like so
```
let df = ctx.sql(r#"
SELECT *
from demo
"#).await?;
```
gives the expected results
```
+----+---------+
| id | payload |
+----+---------+
| 1 | one |
| 2 | two |
+----+---------+
```
Now I have a usecase where the payload should be an array. So something like
this
```
+----+---------+
| id | payload |
+----+---------+
| 1 | [piano, guitar, drums] |
| 2 | [violin, piano] |
+----+---------+
```
How may I go about this?
changing the `vec_of_strings` to `vec_of_vecs` fails. I mean this
```
let vec_of_vecs: Vec<Vec<String>> = vec![
vec!["piano".to_string(), "guitar".to_string(), "drums".to_string()],
vec!["violin".to_string(), "guitar".to_string()]
];
```
When used to create the batch like this
```
let batch = RecordBatch::try_new(
schema,
vec![
Arc::new(Int32Array::from_slice([1, 2])),
Arc::new(StringArray::from(vec_of_vecs)),
],
)?;
```
Fails to compile with the error
```
|
80 | Arc::new(StringArray::from(vec_of_vecs)),
| ----------------- ^^^^^^^^^^^ the trait
`From<Vec<Vec<std::string::String>>>` is not implemented for
`GenericByteArray<GenericStringType<i32>>`
| |
| required by a bound introduced by this call
|
= help: the following other types implement trait `From<T>`:
<GenericByteArray<GenericBinaryType<OffsetSize>> as
From<GenericByteArray<GenericStringType<OffsetSize>>>>
<GenericByteArray<GenericBinaryType<OffsetSize>> as
From<Vec<&[u8]>>>
<GenericByteArray<GenericBinaryType<OffsetSize>> as
From<Vec<Option<&[u8]>>>>
<GenericByteArray<GenericBinaryType<T>> as
From<GenericListArray<T>>>
<GenericByteArray<GenericStringType<OffsetSize>> as
From<GenericByteArray<GenericBinaryType<OffsetSize>>>>
<GenericByteArray<GenericStringType<OffsetSize>> as
From<GenericListArray<OffsetSize>>>
<GenericByteArray<GenericStringType<OffsetSize>> as
From<Vec<&str>>>
<GenericByteArray<GenericStringType<OffsetSize>> as
From<Vec<Option<&str>>>>
and 3 others
```
Any idea on how I may achieve the above?
GitHub link: https://github.com/apache/datafusion/discussions/6398
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