我只使用带有 SQLAlchemy核心的flask框架。从'select'语句返回的结果集包含数千条记录。我想使用分页来避免内存错误。如何动态地为任何页面使用游标获取api GET方法的JSON输出？我已经尝试了How to use cursor() for pagination?中接受的解决方案，但无法完全正确。请指导。使用PostgreSQL 9.4 我尝试过的选项：
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<html>
<head>
<script src="angleoftriangle.js"></script>
<link rel="stylesheet" type="text/css" href="angleoftriangle.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.2/jquery.min.js"></script>
</head>
<body>
<div id="coverbox">
<div id="equilateral-try">
</div>
<form id="text" onsubmit="return areaval()">
<p id="heading1"style="position:absolute;top:8%;left:20%;font-size:22px;color:black;">Acute Triangle</p>
<p id="heading5"style="position:absolute;top:42%;left:20%;font-size:20px;color:black;">abc<90deg.</p>
<input type="text" value ="" id="number" style="position:absolute;width:8%;height:4%;left:60%;top:40%;outline:none;border:none;font-size:25px;background-color:transparent;" placeholder="b"required>
<input type="text" value ="" id="acure" style="position:absolute;width:8%;height:4%;left:78%;top:31%;outline:none;border:none;font-size:25px;z-index:4;background-color:transparent;" placeholder="h"required>
<input type="text" value ="" id="pmet" style="position:absolute;width:8%;height:4%;left:42%;top:25%;outline:none;border:none;font-size:25px;z-index:6;background-color:transparent;" placeholder="a"required>
<input type="text" value ="" id="cmet" style="position:absolute;width:8%;height:4%;left:88%;top:25%;outline:none;border:none;font-size:25px;z-index:5;background-color:transparent;" placeholder="c"required>
<button style="position:absolute;height:20px;left:70%;top:41%;">sol</button>
</form>
<div id="result"style="position:absolute;top:55%;left:20%;font-size:20px;color:#878787;"></div>
<div id="step4.1"style="position:absolute;top:60%;left:20%;font-size:20px;color:#878787;"></div>
<div id="result2.2"style="position:absolute;top:68%;left:20%;font-size:20px;color:#878787;"></div>
<div id="step4.6"style="position:absolute;top:73%;left:20%;font-size:20px;color:#878787;"></div>
<svg height="16%" width="14%"id="strightline">
<line x1="30" y1="0" x2="30" y2="105" style="stroke:black;stroke-width:2" />
</svg>
</div>
<div id="coverbox11">
<div id="right-try">
</div>
<form id="text1" onsubmit="return rightang()">
<p id="heading1"style="position:absolute;top:7%;left:32%;font-size:22px;color:black;">Rightangle Triangle</p>
<p id="heading5"style="position:absolute;top:42%;left:43%;font-size:20px;color:black;"> a=90degree.</p>
<input type="text" value ="" id="oppsite" style="position:absolute;width:8%;height:4%;left:38%;top:23%;outline:none;border:none;font-size:25px;background-color:transparent;" placeholder="a"required>
<input type="text" value ="" id="hidgt" style="position:absolute;width:8%;height:4%;left:48%;top:23%;outline:none;border:none;font-size:25px;z-index:20;background-color:transparent;" placeholder="h"required>
<input type="text" value ="" id="adjacent" style="position:absolute;width:8%;height:4%;left:53%;top:37%;outline:none;border:none;font-size:25px;z-index:4;background-color:transparent;" placeholder="b"required>
<input type="text" value ="" id="hyper" style="position:absolute;width:8%;height:4%;left:68%;top:23%;outline:none;border:none;font-size:25px;z-index:6;background-color:transparent;" placeholder="c"required>
<button style="position:absolute;height:20px;left:64%;top:38%;">sol</button>
</form>
<div id="raitresult"style="position:absolute;top:55%;left:43%;font-size:20px;color:#878787;"></div>
<div id="step5.1"style="position:absolute;top:60%;left:43%;font-size:20px;color:#878787;"></div>
<div id="periresult2"style="position:absolute;top:70%;left:43%;font-size:20px;color:#878787;"></div>
<div id="step5.5"style="position:absolute;top:75%;left:43%;font-size:20px;color:#878787;"></div>
<div id="periresult3"style="position:absolute;top:85%;left:43%;font-size:20px;color:#878787;"></div>
<div id="step5.8"style="position:absolute;top:90%;left:43%;font-size:20px;color:#878787;"></div>
</div>
<div id="coverbox12">
<div id="obtuse-try">
</div>
<svg height="15%" width="15%"id="strightline3">
<path id="lineAB" d="M 100 150 l 70 -200" stroke="black" stroke-width="2" fill="none" />
</svg>
<form id="text2" onsubmit="return obtuseang()">
<p id="heading16"style="position:absolute;top:8%;left:20%;font-size:22px;color:black;">Obtuse Triangle</p>
<p id="heading17"style="position:absolute;top:42%;left:30%;font-size:20px;color:black;">a>90degree.</p>
<input type="text" value ="" id="oppsite1" style="position:absolute;width:8%;height:4%;left:48%;top:38%;outline:none;border:none;font-size:25px;background-color:transparent;" placeholder="b"required>
<input type="text" value ="" id="oppsite2" style="position:absolute;width:8%;height:4%;left:58%;top:28%;outline:none;border:none;font-size:25px;z-index:16;background-color:transparent;" placeholder="h"required>
<input type="text" value ="" id="oppsite6" style="position:absolute;width:8%;height:4%;left:71%;top:23%;outline:none;border:none;font-size:25px;z-index:16;background-color:transparent;" placeholder="c"required>
<input type="text" value ="" id="oppsite7" style="position:absolute;width:8%;height:4%;left:36%;top:23%;outline:none;border:none;font-size:25px;z-index:16;background-color:transparent;" placeholder="a"required>
<button style="position:absolute;height:20px;left:58%;top:39%;">sol</button>
</form>
<div id="raitresult43"style="position:absolute;top:55%;left:30%;font-size:20px;color:#878787;"></div>
<div id="step6.1"style="position:absolute;top:60%;left:30%;font-size:20px;color:#878787;"></div>
<div id="obtuseresult"style="position:absolute;top:70%;left:30%;font-size:20px;color:#878787;"></div>
<div id="stepfine"style="position:absolute;top:75%;left:30%;font-size:20px;color:#878787;"></div>
</div>
<p id="heading19"style="position:absolute;top:-1%;left:30%;font-size:28px;color:blue;">Different types of triangle in angle method.</p>
</body>
</html>我想通过在请求标头中传递参数来控制每页中要打印的记录数，如下所示：
curl -b cookies.txt -X POST http://localhost:8081/test/api/v1.0/docs_page/1 -H'max_per_page：4'-H'Content-type：application / json'
@app.route('/test/api/v1.0/docs_page/<int:page>', methods=['POST'])
def search_docs_page(page):
if 'id' in session:
doc_list = []
no_of_pgs = 0
doc_list = common_search_code()
# doc_list is a resultset after querying the table for a set of query condition
header_dict = dict(request.headers)
for i in header_dict.items():
if i == 'Max-Per-Page':
max_per_pg = int(header_dict[i])
no_of_pgs = len(doc_list) / max_per_pg
print 'number of doc: ' + str(len(doc_list))
print 'number of pages: ' + str(no_of_pgs)
print 'max per page:' + str(max_per_pg)
print 'page number: '+ str(page)
page = int(request.args.get(page, type=int, default=1))
pagination = Pagination(page=page,
total=len(doc_list),
search=True, record_name='documents')
return jsonify({'pagination': list(pagination.__dict__),
'doc_list': doc_list}), 200
return jsonify({'message': "Unauthorized"}), 401
答案 0 :(得分：2)
目前，我已对上述代码进行了更改，以此方式工作：
@app.route('/test/api/v1.0/docs_page2', methods=['POST'])
def search_docs_page2():
if 'id' in session:
docs = []
no_of_pgs = 0
header_dict = dict(request.headers)
for k in header_dict:
print header_dict[k], 'key', k
if 'Max-Per-Page' in header_dict.keys():
max_per_pg = int(header_dict['Max-Per-Page'])
page_no = int(request.headers.get('page_no', type=int, default=1))
offset1 = (page_no - 1) * max_per_pg
query1 = common_search_code()
s = query1.limit(max_per_pg).offset(offset1)
rs = conn.execute(s)
for r in rs:
docs.append(dict(r))
# no_of_pgs = float(len(doc_list) / float(max_per_pg))
no_of_pgs = float(len(docs) / float(max_per_pg))
no_of_pgs = int(math.ceil(no_of_pgs))
print 'number of doc: ' + str(len(docs))
print 'number of pages: ' + str(no_of_pgs)
print 'max per page:' + str(max_per_pg)
# docs.append(doc_list[offset:(offset + max_per_pg)])
return jsonify({'docs': docs,
'no_of_pages': str(no_of_pgs)}), 200
return jsonify({'message': "Max. per page not specified"}), 400
return jsonify({'message': "Unauthorized"}), 401
相同的卷曲：
curl -b cookies.txt -X POST http://localhost:8081/test/api/v1.0/docs_page2 -H 'max_per_page:4' -H 'Content-type:application/json' -H 'page_no:2'