Using pydantic to validate form data

htmx_contact/main.py

@@ -1,15 +1,23 @@
+import logging
+
 from flask import Blueprint
+from flask import flash
 from flask import redirect
 from flask import render_template
 from flask import request
 from flask_login import current_user
 from flask_login import login_required
+from pydantic import ValidationError
 from sqlalchemy import and_
 from sqlalchemy import or_
 from sqlalchemy import select
 
 from htmx_contact import Session
 from htmx_contact.models import Contact
+from htmx_contact.validators import NewContactValidator
+from htmx_contact.validators import repack_validation_errors
+
+logger = logging.getLogger(__name__)
 
 bp = Blueprint("main", __name__, url_prefix="/")
 
@@ -47,6 +55,24 @@ def contacts():
     return render_template("contacts.html", contacts=results)
 
 
-@bp.route("/contacts/new", methods=["GET"])
+@bp.route("/contacts/new", methods=["GET", "POST"])
 def new_contact():
-    return render_template("new_contact.html")
+    if request.method == "POST":
+        try:
+            validated_form = NewContactValidator(
+                # first_name=request.form.get("first_name"),
+                # last_name=request.form.get("last_name"),
+                # phone=request.form.get("phone"),
+                # email=request.form.get("email"),
+                **request.form
+            )
+            with Session.begin() as session:
+                contact = Contact(**validated_form)
+                session.add(contact)
+                session.commit()
+            flash("New Contacted added!")
+            return redirect("/contacts")
+        except ValidationError as error:
+            logger.info("validation error: %r", error)
+            return render_template("new_contact.html", errors=repack_validation_errors(error.errors()))
+    return render_template("new_contact.html", errors={})

htmx_contact/templates/new_contact.html

@@ -2,4 +2,35 @@
 
 {% block content %}
 <h1>New Contact</h1>
+
+
+<form action="/contacts/new" method="post">
+    <fieldset>
+        <legend>Contact Values</legend>
+        <p>
+            <label for="email">Email</label>
+            <input name="email" id="email" type="email" placeholder="Email">
+            <span class="error">{{ errors.get('email','') }}</span>
+        </p>
+        <p>
+            <label for="first_name">First Name</label>
+            <input name="first_name" id="first_name" type="text" placeholder="First Name">
+            <span class="error">{{ errors.get('first_name','') }}</span>
+        </p>
+        <p>
+            <label for="last_name">Last Name</label>
+            <input name="last_name" id="last_name" type="text" placeholder="Last Name">
+            <span class="error">{{ errors.get('last_name', '') }}</span>
+        </p>
+        <p>
+            <label for="phone">Phone</label>
+            <input name="phone" id="phone" type="text" placeholder="Phone">
+            <span class="error">{{ errors.get('phone','') }}</span>
+        </p>
+        <button>Save</button>
+    </fieldset>
+</form>
+<p>
+    <a href="/contacts">Back</a>
+</p>
 {% endblock %}

htmx_contact/validators.py

@@ -0,0 +1,34 @@
+import re
+
+from pydantic import BaseModel
+from pydantic import Field
+from pydantic import field_validator
+
+from htmx_contact.models import PHONE_REGEX
+
+EMAIL_REGEX = r'^[\w\-\.]+@([\w-]+\.)+[\w-]{2,}$'
+
+
+def repack_validation_errors(errors):
+    repackaged_errors = {error.get('loc')[0]: error.get('msg') for error in errors}
+    return repackaged_errors
+
+
+class NewContactValidator(BaseModel):
+    first_name: str = Field(min_length=2, max_length=30)
+    last_name: str = Field(min_length=2, max_length=30)
+    phone: str = Field(max_length=30)
+    email: str = Field(max_length=120)
+
+    # Field Validators used to prevent regex patterns returned in error message
+    @field_validator('phone')
+    def must_match_phone_pattern(value):
+        if not bool(re.match(PHONE_REGEX, value)):
+            raise ValueError("not a valid phone number. Please review and resubmit.")
+        return value
+
+    @field_validator('email')
+    def must_match_email_pattern(value):
+        if not bool(re.match(EMAIL_REGEX, value)):
+            raise ValueError("not a valid email. Please review and resubmit.")
+        return value

tests/test_validators.py

@@ -0,0 +1,21 @@
+import pytest
+from pydantic import ValidationError
+
+from htmx_contact.validators import NewContactValidator
+from htmx_contact.validators import repack_validation_errors
+
+
+def test_new_contact_errors():
+    with pytest.raises(ValidationError) as error:
+        NewContactValidator(first_name="Drew", last_name="bednar", phone="666-7777-3333", email="not a valid email")
+    assert len(error.value.errors()) == 2
+
+
+def test_repackage_errors():
+    with pytest.raises(ValidationError) as error:
+        NewContactValidator(first_name="Drew", last_name="bednar", phone="666-7777-3333", email="not a valid email")
+
+    repackaged_errors = repack_validation_errors(error.value.errors())
+    assert len(repackaged_errors) == 2
+    assert 'not a valid phone number' in repackaged_errors['phone']
+    assert 'not a valid email' in repackaged_errors['email']