From fa3d808327c170ec7d61d2a45c9f6602c14fb2d5 Mon Sep 17 00:00:00 2001
From: "R. Tyler Croy" <rtyler@brokenco.de>
Date: Tue, 13 Aug 2024 01:46:11 +0000
Subject: [PATCH] feat: restore the TryFrom for DeltaTablePartition

I actually used this functionality :smile:

It was removed in #2037 but I think it's handy and worth keeping around
:shrug:
---
 crates/core/src/schema/partitions.rs | 48 ++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/crates/core/src/schema/partitions.rs b/crates/core/src/schema/partitions.rs
index d2b2e84979..d3c34a4bab 100644
--- a/crates/core/src/schema/partitions.rs
+++ b/crates/core/src/schema/partitions.rs
@@ -276,6 +276,37 @@ impl DeltaTablePartition {
     }
 }
 
+///
+/// A HivePartition string is represented by a "key=value" format.
+///
+/// ```rust
+/// # use delta_kernel::expressions::Scalar;
+/// use deltalake_core::DeltaTablePartition;
+///
+/// let hive_part = "ds=2023-01-01";
+/// let partition = DeltaTablePartition::try_from(hive_part).unwrap();
+/// assert_eq!("ds", partition.key);
+/// assert_eq!(Scalar::String("2023-01-01".into()), partition.value);
+/// ```
+impl TryFrom<&str> for DeltaTablePartition {
+    type Error = DeltaTableError;
+
+    /// Try to create a DeltaTable partition from a HivePartition string.
+    /// Returns a DeltaTableError if the string is not in the form of a HivePartition.
+    fn try_from(partition: &str) -> Result<Self, DeltaTableError> {
+        let partition_splitted: Vec<&str> = partition.split('=').collect();
+        match partition_splitted {
+            partition_splitted if partition_splitted.len() == 2 => Ok(DeltaTablePartition {
+                key: partition_splitted[0].to_owned(),
+                value: Scalar::String(partition_splitted[1].to_owned()),
+            }),
+            _ => Err(DeltaTableError::PartitionError {
+                partition: partition.to_string(),
+            }),
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -326,4 +357,21 @@ mod tests {
             "date NOT IN ('2023-11-04', '2023-06-07')",
         );
     }
+
+    #[test]
+    fn tryfrom_invalid() {
+        let buf = "this-is-not-a-partition";
+        let partition = DeltaTablePartition::try_from(buf);
+        assert!(partition.is_err());
+    }
+
+    #[test]
+    fn tryfrom_valid() {
+        let buf = "ds=2024-04-01";
+        let partition = DeltaTablePartition::try_from(buf);
+        assert!(partition.is_ok());
+        let partition = partition.unwrap();
+        assert_eq!(partition.key, "ds");
+        assert_eq!(partition.value, Scalar::String("2024-04-01".into()));
+    }
 }