datasette install -e option, closes #2106

datasette/cli.py

@@ -351,13 +351,21 @@ def package(
     type=click.Path(exists=True),
     help="Install from requirements file",
 )
-def install(packages, upgrade, requirement):
+@click.option(
+    "-e",
+    "--editable",
+    type=click.Path(readable=True, exists=True, dir_okay=True, file_okay=False),
+    help="Install a project in editable mode from this path",
+)
+def install(packages, upgrade, requirement, editable):
     """Install plugins and packages from PyPI into the same environment as Datasette"""
-    if not packages and not requirement:
+    if not packages and not requirement and not editable:
         raise click.UsageError("Please specify at least one package to install")
     args = ["pip", "install"]
     if upgrade:
         args += ["--upgrade"]
+    if editable:
+        args += ["--editable", str(editable)]
     if requirement:
         args += ["-r", requirement]
     args += list(packages)

docs/cli-reference.rst

@@ -350,9 +350,10 @@ Would install the `datasette-cluster-map <https://datasette.io/plugins/datasette
       Install plugins and packages from PyPI into the same environment as Datasette
 
     Options:
-      -U, --upgrade           Upgrade packages to latest version
-      -r, --requirement PATH  Install from requirements file
-      --help                  Show this message and exit.
+      -U, --upgrade             Upgrade packages to latest version
+      -r, --requirement PATH    Install from requirements file
+      -e, --editable DIRECTORY  Install a project in editable mode from this path
+      --help                    Show this message and exit.
 
 
 .. [[[end]]]