Stripe subscription checkout session creation

<p>I need to integrate Stripe Checkout for subscription payments. Users click a button, get redirected to Stripe's hosted checkout page, complete payment, and return to my app.</p>

<p>Create Stripe Checkout sessions:</p> <div class="highlight"><pre><span></span><code><span class="kn">import</span><span class="w"> </span><span class="nn">stripe</span> <span class="kn">from</span><span class="w"> </span><span class="nn">fastapi</span><span class="w"> </span><span class="kn">import</span> <span class="n">APIRouter</span> <span class="n">stripe</span><span class="o">.</span><span class="n">api_key</span> <span class="o">=</span> <span class="n">settings</span><span class="o">.</span><span class="n">stripe_secret_key</span> <span class="n">router</span> <span class="o">=</span> <span class="n">APIRouter</span><span class="p">()</span> <span class="nd">@router</span><span class="o">.</span><span class="n">post</span><span class="p">(</span><span class="s1">'/billing/checkout'</span><span class="p">)</span> <span class="k">async</span> <span class="k">def</span><span class="w"> </span><span class="nf">create_checkout</span><span class="p">(</span><span class="n">user</span><span class="p">:</span> <span class="n">CurrentUser</span><span class="p">,</span> <span class="n">db</span><span class="p">:</span> <span class="n">DbSession</span><span class="p">):</span> <span class="n">db_user</span> <span class="o">=</span> <span class="k">await</span> <span class="n">get_user</span><span class="p">(</span><span class="n">db</span><span class="p">,</span> <span class="n">user</span><span class="o">.</span><span class="n">id</span><span class="p">)</span> <span class="c1"># Create/get Stripe customer:</span> <span class="k">if</span> <span class="ow">not</span> <span class="n">db_user</span><span class="o">.</span><span class="n">stripe_customer_id</span><span class="p">:</span> <span class="n">customer</span> <span class="o">=</span> <span class="n">stripe</span><span class="o">.</span><span class="n">Customer</span><span class="o">.</span><span class="n">create</span><span class="p">(</span> <span class="n">email</span><span class="o">=</span><span class="n">db_user</span><span class="o">.</span><span class="n">email</span><span class="p">,</span> <span class="n">metadata</span><span class="o">=</span><span class="p">{</span><span class="s1">'user_id'</span><span class="p">:</span> <span class="nb">str</span><span class="p">(</span><span class="n">user</span><span class="o">.</span><span class="n">id</span><span class="p">)},</span> <span class="p">)</span> <span class="n">db_user</span><span class="o">.</span><span class="n">stripe_customer_id</span> <span class="o">=</span> <span class="n">customer</span><span class="p">[</span><span class="s1">'id'</span><span class="p">]</span> <span class="k">await</span> <span class="n">db</span><span class="o">.</span><span class="n">commit</span><span class="p">()</span> <span class="n">session</span> <span class="o">=</span> <span class="n">stripe</span><span class="o">.</span><span class="n">checkout</span><span class="o">.</span><span class="n">Session</span><span class="o">.</span><span class="n">create</span><span class="p">(</span> <span class="n">customer</span><span class="o">=</span><span class="n">db_user</span><span class="o">.</span><span class="n">stripe_customer_id</span><span class="p">,</span> <span class="n">mode</span><span class="o">=</span><span class="s1">'subscription'</span><span class="p">,</span> <span class="n">line_items</span><span class="o">=</span><span class="p">[{</span><span class="s1">'price'</span><span class="p">:</span> <span class="n">settings</span><span class="o">.</span><span class="n">stripe_pro_price_id</span><span class="p">,</span> <span class="s1">'quantity'</span><span class="p">:</span> <span class="mi">1</span><span class="p">}],</span> <span class="n">success_url</span><span class="o">=</span><span class="sa">f</span><span class="s1">'</span><span class="si">{</span><span class="n">settings</span><span class="o">.</span><span class="n">frontend_url</span><span class="si">}</span><span class="s1">/billing/success?session_id=</span><span class="se">{{</span><span class="s1">CHECKOUT_SESSION_ID</span><span class="se">}}</span><span class="s1">'</span><span class="p">,</span> <span class="n">cancel_url</span><span class="o">=</span><span class="sa">f</span><span class="s1">'</span><span class="si">{</span><span class="n">settings</span><span class="o">.</span><span class="n">frontend_url</span><span class="si">}</span><span class="s1">/billing/cancel'</span><span class="p">,</span> <span class="n">metadata</span><span class="o">=</span><span class="p">{</span><span class="s1">'user_id'</span><span class="p">:</span> <span class="nb">str</span><span class="p">(</span><span class="n">user</span><span class="o">.</span><span class="n">id</span><span class="p">)},</span> <span class="n">allow_promotion_codes</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span> <span class="p">)</span> <span class="k">return</span> <span class="p">{</span><span class="s1">'checkout_url'</span><span class="p">:</span> <span class="n">session</span><span class="p">[</span><span class="s1">'url'</span><span class="p">]}</span> <span class="c1"># Confirm via webhook (not success_url):</span> <span class="k">async</span> <span class="k">def</span><span class="w"> </span><span class="nf">activate_subscription</span><span class="p">(</span><span class="n">user_id</span><span class="p">:</span> <span class="nb">str</span><span class="p">,</span> <span class="n">subscription_id</span><span class="p">:</span> <span class="nb">str</span><span class="p">):</span> <span class="k">await</span> <span class="n">db</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span> <span class="n">update</span><span class="p">(</span><span class="n">User</span><span class="p">)</span><span class="o">.</span><span class="n">where</span><span class="p">(</span><span class="n">User</span><span class="o">.</span><span class="n">id</span> <span class="o">==</span> <span class="n">user_id</span><span class="p">)</span> <span class="o">.</span><span class="n">values</span><span class="p">(</span><span class="n">subscription_status</span><span class="o">=</span><span class="s1">'active'</span><span class="p">,</span> <span class="n">stripe_subscription_id</span><span class="o">=</span><span class="n">subscription_id</span><span class="p">)</span> <span class="p">)</span> </code></pre></div> <p>Key points: - {CHECKOUT_SESSION_ID} is a Stripe template variable, filled on redirect - Confirm payment via webhook checkout.session.completed, not the success URL - Always create a Stripe Customer and link to your user -- needed for portal/subscriptions - Use mode='payment' for one-time payments, 'subscription' for recurring</p>