mirror of https://github.com/tiangolo/fastapi.git
Reverted the changes in docs unrelated to the main idea of PR
This commit is contained in:
Yurii Motov
parent
978351dbe6
commit
2ceaa96981
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@ -73,60 +73,6 @@ They will receive an error response telling them that the field `extra` is not a
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}
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```
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## Default Fields
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Form-encoded data has some quirks that can make working with pydantic models counterintuitive.
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Say, for example, you were generating an HTML form from a model,
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and that model had a boolean field in it that you wanted to display as a checkbox
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with a default `True` value:
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{* ../../docs_src/request_form_models/tutorial003_an_py39.py hl[11,10:23] *}
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This works as expected when the checkbox remains checked,
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the form encoded data in the request looks like this:
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```formencoded
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checkbox=on
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```
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and the JSON response is also correct:
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```json
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{"checkbox":true}
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```
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When the checkbox is *unchecked*, though, something strange happens.
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The submitted form data is *empty*,
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and the returned JSON data still shows `checkbox` still being `true`!
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This is because checkboxes in HTML forms don't work exactly like the boolean inputs we expect,
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when a checkbox is checked, if there is no `value` attribute, the value will be `"on"`,
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and [the field will be omitted altogether if unchecked](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/input/checkbox).
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When dealing with form models with defaults,
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we need to take special care to handle cases where the field being *unset* has a specific meaning.
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We also don't want to just treat any time the value is unset as ``False`` -
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that would defeat the purpose of the default!
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We want to specifically correct the behavior when it is used in the context of a *form.*
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In some cases, we can resolve the problem by changing or removing the default,
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but we don't always have that option -
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particularly when the model is used in other places than the form
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The recommended approach is to duplicate your model:
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/// note
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Take care to ensure that your duplicate models don't diverge,
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e.g. if you are using sqlmodel,
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where you may end up with `MyModel`, `MyModelCreate`, and `MyModelCreateForm`.
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///
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{* ../../docs_src/request_form_models/tutorial004_an_py39.py hl[7,13:25] *}
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## Summary { #summary }
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You can use Pydantic models to declare form fields in FastAPI. 😎
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@ -1,46 +0,0 @@
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from fastapi import FastAPI, Form, Request
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from fastapi.responses import HTMLResponse
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from fastapi.templating import Jinja2Templates
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from jinja2 import DictLoader, Environment
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from pydantic import BaseModel
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class MyModel(BaseModel):
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checkbox: bool = True
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form_template = """
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<form action="/form" method="POST">
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{% for field_name, field in model.model_fields.items() %}
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<p>
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<label for="{{ field_name }}">{{ field_name }}</label>
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{% if field.annotation.__name__ == "bool" %}
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<input type="checkbox" name="{{field_name}}"
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{% if field.default %}
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checked="checked"
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{% endif %}
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>
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{% else %}
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<input name="{{ field_name }}">
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{% endif %}
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</p>
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{% endfor %}
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<button type="submit">Submit</button>
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</form>
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"""
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loader = DictLoader({"form.html": form_template})
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templates = Jinja2Templates(env=Environment(loader=loader))
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app = FastAPI()
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@app.get("/form", response_class=HTMLResponse)
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async def show_form(request: Request):
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return templates.TemplateResponse(
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request=request, name="form.html", context={"model": MyModel}
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)
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@app.post("/form")
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async def submit_form(data: MyModel = Form()) -> MyModel:
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return data
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@ -1,48 +0,0 @@
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from typing import Annotated
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from fastapi import FastAPI, Form, Request
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from fastapi.responses import HTMLResponse
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from fastapi.templating import Jinja2Templates
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from jinja2 import DictLoader, Environment
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from pydantic import BaseModel
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class MyModel(BaseModel):
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checkbox: bool = True
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form_template = """
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<form action="/form" method="POST">
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{% for field_name, field in model.model_fields.items() %}
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<p>
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<label for="{{ field_name }}">{{ field_name }}</label>
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{% if field.annotation.__name__ == "bool" %}
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<input type="checkbox" name="{{field_name}}"
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{% if field.default %}
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checked="checked"
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{% endif %}
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>
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{% else %}
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<input name="{{ field_name }}">
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{% endif %}
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</p>
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{% endfor %}
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<button type="submit">Submit</button>
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</form>
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"""
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loader = DictLoader({"form.html": form_template})
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templates = Jinja2Templates(env=Environment(loader=loader))
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app = FastAPI()
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@app.get("/form", response_class=HTMLResponse)
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async def show_form(request: Request):
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return templates.TemplateResponse(
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request=request, name="form.html", context={"model": MyModel}
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)
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@app.post("/form")
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async def submit_form(data: Annotated[MyModel, Form()]) -> MyModel:
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return data
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@ -1,57 +0,0 @@
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from typing import cast
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from fastapi import FastAPI, Form, Request
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from fastapi.responses import HTMLResponse
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from fastapi.templating import Jinja2Templates
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from jinja2 import DictLoader, Environment
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from pydantic import BaseModel, model_validator
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class MyModel(BaseModel):
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checkbox: bool = True
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class MyModelForm(MyModel):
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@model_validator(mode="before")
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def handle_defaults(cls, value: dict) -> dict:
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if "checkbox" not in value:
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value["checkbox"] = False
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return value
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form_template = """
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<form action="/form" method="POST">
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{% for field_name, field in model.model_fields.items() %}
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<p>
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<label for="{{ field_name }}">{{ field_name }}</label>
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{% if field.annotation.__name__ == "bool" %}
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<input type="checkbox" name="{{field_name}}"
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{% if field.default %}
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checked="checked"
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{% endif %}
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>
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{% else %}
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<input name="{{ field_name }}">
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{% endif %}
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</p>
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{% endfor %}
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<button type="submit">Submit</button>
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</form>
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"""
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loader = DictLoader({"form.html": form_template})
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templates = Jinja2Templates(env=Environment(loader=loader))
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app = FastAPI()
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@app.get("/form", response_class=HTMLResponse)
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async def show_form(request: Request):
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return templates.TemplateResponse(
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request=request, name="form.html", context={"model": MyModel}
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)
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@app.post("/form")
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async def submit_form(data: MyModelForm = Form()) -> MyModel:
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data = cast(MyModel, data)
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return data
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@ -1,57 +0,0 @@
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from typing import Annotated, cast
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from fastapi import FastAPI, Form, Request
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from fastapi.responses import HTMLResponse
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from fastapi.templating import Jinja2Templates
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from jinja2 import DictLoader, Environment
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from pydantic import BaseModel, ValidationInfo, model_validator
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class MyModel(BaseModel):
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checkbox: bool = True
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class MyModelForm(MyModel):
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@model_validator(mode="before")
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def handle_defaults(cls, value: dict, info: ValidationInfo) -> dict:
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if "checkbox" not in value:
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value["checkbox"] = False
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return value
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form_template = """
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<form action="/form" method="POST">
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{% for field_name, field in model.model_fields.items() %}
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<p>
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<label for="{{ field_name }}">{{ field_name }}</label>
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{% if field.annotation.__name__ == "bool" %}
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<input type="checkbox" name="{{field_name}}"
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{% if field.default %}
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checked="checked"
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{% endif %}
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>
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{% else %}
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<input name="{{ field_name }}">
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{% endif %}
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</p>
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{% endfor %}
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<button type="submit">Submit</button>
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</form>
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"""
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loader = DictLoader({"form.html": form_template})
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templates = Jinja2Templates(env=Environment(loader=loader))
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app = FastAPI()
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@app.get("/form", response_class=HTMLResponse)
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async def show_form(request: Request):
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return templates.TemplateResponse(
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request=request, name="form.html", context={"model": MyModel}
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)
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@app.post("/form")
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async def submit_form(data: Annotated[MyModelForm, Form()]) -> MyModel:
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data = cast(MyModel, data)
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return data
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@ -1,57 +0,0 @@
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from typing import cast
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from fastapi import FastAPI, Form, Request
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from fastapi.responses import HTMLResponse
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from fastapi.templating import Jinja2Templates
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from jinja2 import DictLoader, Environment
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from pydantic import BaseModel, root_validator
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class MyModel(BaseModel):
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checkbox: bool = True
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class MyModelForm(BaseModel):
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@root_validator(pre=True)
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def handle_defaults(cls, value: dict) -> dict:
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if "checkbox" not in value:
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value["checkbox"] = False
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return value
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form_template = """
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<form action="/form" method="POST">
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{% for field_name, field in model.model_fields.items() %}
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<p>
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<label for="{{ field_name }}">{{ field_name }}</label>
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{% if field.annotation.__name__ == "bool" %}
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<input type="checkbox" name="{{field_name}}"
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{% if field.default %}
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checked="checked"
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{% endif %}
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>
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{% else %}
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<input name="{{ field_name }}">
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{% endif %}
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</p>
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{% endfor %}
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<button type="submit">Submit</button>
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</form>
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"""
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loader = DictLoader({"form.html": form_template})
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templates = Jinja2Templates(env=Environment(loader=loader))
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app = FastAPI()
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@app.get("/form", response_class=HTMLResponse)
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async def show_form(request: Request):
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return templates.TemplateResponse(
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request=request, name="form.html", context={"model": MyModel}
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)
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@app.post("/form")
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async def submit_form(data: MyModelForm = Form()) -> MyModel:
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data = cast(MyModel, data)
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return data
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@ -1,57 +0,0 @@
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from typing import Annotated, cast
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from fastapi import FastAPI, Form, Request
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from fastapi.responses import HTMLResponse
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from fastapi.templating import Jinja2Templates
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from jinja2 import DictLoader, Environment
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from pydantic import BaseModel, root_validator
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class MyModel(BaseModel):
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checkbox: bool = True
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class MyModelForm(MyModel):
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@root_validator(pre=True)
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def handle_defaults(cls, value: dict) -> dict:
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if "checkbox" not in value:
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value["checkbox"] = False
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return value
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form_template = """
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<form action="/form" method="POST">
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{% for field_name, field in model.model_fields.items() %}
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<p>
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<label for="{{ field_name }}">{{ field_name }}</label>
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{% if field.annotation.__name__ == "bool" %}
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<input type="checkbox" name="{{field_name}}"
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{% if field.default %}
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checked="checked"
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{% endif %}
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>
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{% else %}
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<input name="{{ field_name }}">
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{% endif %}
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</p>
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{% endfor %}
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<button type="submit">Submit</button>
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</form>
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"""
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loader = DictLoader({"form.html": form_template})
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templates = Jinja2Templates(env=Environment(loader=loader))
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app = FastAPI()
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@app.get("/form", response_class=HTMLResponse)
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async def show_form(request: Request):
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return templates.TemplateResponse(
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request=request, name="form.html", context={"model": MyModel}
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)
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@app.post("/form")
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async def submit_form(data: Annotated[MyModelForm, Form()]) -> MyModel:
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data = cast(MyModel, data)
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return data
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