Add mbtiles meta-get utility (#701)

* Add functionality to retrieve a metadata value in an mbtiles file by
key; simple implementation for one of the items in #667
* Also, disable TTY in docker-up `just` target

Cargo.toml

@@ -90,6 +90,7 @@ actix-cors = "0.6"
 actix-http = "3"
 actix-rt = "2"
 actix-web = "4"
+anyhow = "1.0"
 async-trait = "0.1"
 brotli = "3"
 cargo-husky = { version = "1", features = ["user-hooks"], default-features = false }
@@ -119,3 +120,4 @@ sqlx = { version = "0.6", features = ["offline", "sqlite", "runtime-actix-native
 subst = { version = "0.2", features = ["yaml"] }
 thiserror = "1"
 tilejson = "0.3"
+tokio = { version = "1.28.2", features = ["macros"] }

docs/src/SUMMARY.md

@@ -20,4 +20,5 @@
   - [Using with deck.gl](using-with-deck-gl.md)
   - [Using with Mapbox](using-with-mapbox.md)
   - [Recipes](recipes.md)
+- [Tools](tools.md)
 - [Development](development.md)

docs/src/tools.md

@@ -0,0 +1,7 @@
+# Tools
+
+## MBTiles tools
+A small utility that allows users to interact with mbtiles files from the CLI as follows: `mbtiles <command> ...`
+
+#### `meta-get`
+Retrieve a metadata value by its name: `mbtiles meta-get <file.mbtiles> <key>`. See `mbtiles meta-get --help` to see available options.

justfile

@@ -47,7 +47,7 @@ start-legacy: (docker-up "db-legacy")
 [private]
 docker-up name:
     docker-compose up -d {{ name }}
-    docker-compose run --rm db-is-ready
+    docker-compose run -T --rm db-is-ready
 
 alias _down := stop
 alias _stop-db := stop

martin-mbtiles/Cargo.toml

@@ -23,7 +23,9 @@ thiserror.workspace = true
 tilejson.workspace = true
 
 # Bin dependencies
+anyhow.workspace = true
 clap.workspace = true
+tokio.workspace = true
 
 [dev-dependencies]
 # For testing, might as well use the same async framework as the Martin itself

martin-mbtiles/sqlx-data.json

@@ -1,5 +1,23 @@
 {
   "db": "SQLite",
+  "386a375cf65c3e5aef51deffc99d23bd852ba445c1058aed380fe83bed618c29": {
+    "describe": {
+      "columns": [
+        {
+          "name": "value",
+          "ordinal": 0,
+          "type_info": "Text"
+        }
+      ],
+      "nullable": [
+        true
+      ],
+      "parameters": {
+        "Right": 1
+      }
+    },
+    "query": "SELECT value from metadata where name = ?"
+  },
   "5b298df51dccbf0d8a22433a99febc59c27dbf204d09a9c1fb0b3bf9aaad284b": {
     "describe": {
       "columns": [

martin-mbtiles/src/bin/main.rs

@@ -1,4 +1,6 @@
+use anyhow::Result;
 use clap::{Parser, Subcommand};
+use martin_mbtiles::Mbtiles;
 use std::path::PathBuf;
 
 #[derive(Parser, Debug)]
@@ -25,6 +27,11 @@ enum Commands {
     MetaGetValue {
         /// MBTiles file to read a value from
         file: PathBuf,
+        /// Value to read
+        key: String,
+        /// Output the raw value
+        #[arg(short, long)]
+        raw: bool,
     },
     /// Sets a single value in the metadata table, or deletes it if no value.
     #[command(name = "meta-set")]
@@ -41,10 +48,31 @@ enum Commands {
     },
 }
 
-fn main() {
+#[tokio::main]
+async fn main() -> Result<()> {
     let args = Args::parse();
 
-    println!("Parsed args:\n");
-    println!("{args:#?}");
-    println!();
+    match args.command {
+        Commands::MetaGetValue { file, key, raw } => {
+            let mbt = Mbtiles::new(&file).await?;
+
+            let value = mbt.get_metadata_value(&key).await?;
+
+            if raw {
+                if let Some(s) = value {
+                    println!("{s}")
+                }
+            } else {
+                match value {
+                    Some(s) => println!(r#"The value for metadata key "{key}" is:\n "{s}""#),
+                    None => println!(r#"No value for metadata key "{key}""#),
+                }
+            }
+        }
+        _ => {
+            unimplemented!("Oops! This command is not yet available, stay tuned for future updates")
+        }
+    }
+
+    Ok(())
 }

martin-mbtiles/src/lib.rs

@@ -75,6 +75,19 @@ impl Mbtiles {
         }
     }
 
+    pub async fn get_metadata_value(&self, key: &str) -> MbtResult<Option<String>> {
+        let mut conn = self.pool.acquire().await?;
+
+        let query = query! {"SELECT value from metadata where name = ?", key};
+        let row = query.fetch_optional(&mut conn).await?;
+        if let Some(row) = row {
+            if let Some(value) = row.value {
+                return Ok(Some(value));
+            }
+        }
+        Ok(None)
+    }
+
     pub async fn get_metadata(&self) -> MbtResult<Metadata> {
         let mut conn = self.pool.acquire().await?;
 
@@ -314,4 +327,29 @@ mod tests {
         );
         assert_eq!(metadata.layer_type, Some("overlay".to_string()));
     }
+
+    #[actix_rt::test]
+    async fn metadata_get_key() {
+        let mbt = Mbtiles::new(Path::new("../tests/fixtures/files/world_cities.mbtiles"))
+            .await
+            .unwrap();
+
+        assert_eq!(
+            mbt.get_metadata_value("bounds").await.unwrap().unwrap(),
+            "-123.123590,-37.818085,174.763027,59.352706"
+        );
+        assert_eq!(
+            mbt.get_metadata_value("name").await.unwrap().unwrap(),
+            "Major cities from Natural Earth data"
+        );
+        assert_eq!(
+            mbt.get_metadata_value("maxzoom").await.unwrap().unwrap(),
+            "6"
+        );
+        assert_eq!(
+            mbt.get_metadata_value("nonexistent_key").await.unwrap(),
+            None
+        );
+        assert_eq!(mbt.get_metadata_value("").await.unwrap(), None);
+    }
 }