BlakeOrth commented on code in PR #8801:
URL: https://github.com/apache/arrow-rs/pull/8801#discussion_r2501104411
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parquet-geospatial/src/crs.rs:
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@@ -0,0 +1,97 @@
+use std::{collections::HashMap, sync::Arc};
+
+use arrow_schema::{Schema, SchemaBuilder};
+use serde_json::{Value, json};
+
+#[derive(Debug)]
+pub enum Crs {
+ Projjson(serde_json::Value),
+ Srid(u64),
+ Other(String),
+}
+
+impl Crs {
+ // TODO: make fallible
+ fn try_from_parquet_str(crs: &str, metadata: &HashMap<String, String>) ->
Self {
+ let de: Value = serde_json::from_str(crs).unwrap();
+
+ // A CRS that does not exist or is empty defaults to 4326
+ // TODO: http link to parquet geospatial doc
+ let Some(crs) = de["crs"].as_str() else {
+ return Crs::Srid(4326);
+ };
+
+ if let Some(key) = crs.strip_prefix("projjson:") {
+ let Some(proj_meta) = metadata.get(key) else {
+ panic!("Failed to find key in meta: {:?}", metadata)
+ };
+
+ Self::Projjson(serde_json::from_str(proj_meta).unwrap())
+ } else if let Some(srid) = crs.strip_prefix("srid:") {
+ Self::Srid(srid.parse().unwrap())
+ } else {
+ if crs.is_empty() {
+ return Self::Srid(4326);
+ }
+
+ Self::Other(crs.to_owned())
+ }
+ }
+
+ // TODO: make fallible
+ pub(super) fn try_from_arrow_str(crs: &str) -> Self {
+ let de: Value = serde_json::from_str(crs).unwrap();
+
+ let crs = match de["crs"] {
+ Value::Null => panic!("CRS must be specified. Inputs crs {crs}"),
+ _ => &de["crs"],
+ };
+
+ match de["crs_type"].as_str() {
+ Some("projjson") => Crs::Projjson(crs.clone()),
+ Some("srid") =>
Crs::Srid(crs.as_number().unwrap().as_u64().unwrap()),
+ _ => Crs::Other(crs.to_string())
+ }
+ }
+
+ pub(super) fn to_arrow_string(&self) -> String {
+ match &self {
+ Self::Projjson(pj) => json!({
+ "crs": pj,
+ "crs_type": "projjson",
+ })
+ .to_string(),
+ Self::Srid(srid) => json!({
+ "crs": srid,
+ "crs_type": "srid",
+ })
+ .to_string(),
+ Self::Other(s) => json!({
+ "crs": s,
+ })
+ .to_string(),
+ }
+ }
+}
+
+// TODO: make fallible
+pub fn parquet_to_arrow(schema: &mut Schema, metadata: &HashMap<String,
String>) {
+ let n_fields = schema.flattened_fields().len();
+ let mut sb: SchemaBuilder = schema.as_ref().into();
+ for i in 0..n_fields {
+ let mut field = sb.field(i).as_ref().clone();
+ // TODO: use consts instead of raw strings
+ if let Some(ext_name) = field.extension_type_name()
+ && ext_name == "geoarrow.wkb"
+ && let Some(ext_meta) =
field.metadata_mut().get_mut("ARROW:extension:metadata")
Review Comment:
This is a much less important question, but this `let` chain seems to have
broken `rustfmt` for this file. `let` chains require 2024 edition, but I looked
at the `rustfmt.toml` for the package and it seems to set the edition to 2024,
so if anyone has thoughts as to why this breaks I'd love to have `rustfmt`
happy again.
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