Webread returns empty stucture, but urlread works,

Question

YoungMin 2023-10-12

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2032179-webread-returns-empty-stucture-but-urlread-works

评论： YoungMin 2023-10-12

采纳的回答： Angelo Yeo

save_before_estate.mat

在 MATLAB Online 中打开

Hi everyone, i have some issue about Webread

this is my code,

key = 'ZgFJoT6d3VEh1qz%2Fv%2Bj6SFAuefvQF%2BlboVR1njEK%2B8LcYTYddXSFE57fmAukUXPovujQLo9Fy05EvPpaGpH0ag%3D%3D';
baseurl_estate = 'http://apis.data.go.kr/1611000/nsdi/IndvdLandPriceService/attr/getIndvdLandPriceAttr?ServiceKey=';
start_year = '2020';
format = 'json';
num_of_row = '20';
for i = 1:height(stn_data)
    url_estate = strcat(baseurl_estate,key,'&pnu=',stn_data.pnu(i,1:end),'&numOfRows=', num_of_row,'&format=',format,'&stdrYear=',start_year);    
    temp_estate = urlread(url_estate);
    temp_estate = jsondecode(temp_estate);
    for j = 1:19
        if ~isempty(temp_estate.indvdLandPrices.field)
            break;
        else
            url_estate = strcat(baseurl_estate,key,'&pnu=',stn_data.pnu(i,1:end-j),'&numOfRows=', num_of_row,'&format=',format,'&stdrYear=',start_year);    
            temp_estate = urlread(url_estate);
            temp_estate = jsondecode(temp_estate);
        end
    end
    if j == 19
        fprintf("%d 에러발생",i)
        cnt = cnt+1;
    end 
    stn_estate(i,1) = temp_estate;
    clear -regexp ^temp
    i
end

In this code, urlread is works well, i mean it can return data

but, when i chagne my code use webread, webread doesn't return value.Webreads return an empty struct with no fields.

I want use webread cause when i use urlread and json, sometimes error was happened

'JSON syntax error at line 1, column 1 (character 1): expected value but found '<'.'

% function stn_data = make_estate(stn_data)
% get estate
% from 공공데이터 포털
% 지번마지막 자리로 결과가 안나오면 뒤에서부터 하나씩 제거
% if when this code delete 5th jibun that is error!!!
key = 'ZgFJoT6d3VEh1qz%2Fv%2Bj6SFAuefvQF%2BlboVR1njEK%2B8LcYTYddXSFE57fmAukUXPovujQLo9Fy05EvPpaGpH0ag%3D%3D';
baseurl_estate = 'http://apis.data.go.kr/1611000/nsdi/IndvdLandPriceService/attr/getIndvdLandPriceAttr?ServiceKey=';
start_year = '2020';
format = 'xml';
num_of_row = '20';
cnt = 0;
% conflict = '1';
% options = weboptions('Timeout', inf,'ContentType','json');
for i = 1:1
    url_estate = strcat(baseurl_estate,key,'&pnu=',stn_data.pnu(i,1:end),'&numOfRows=', num_of_row,'&format=',format,'&stdrYear=',start_year);    
    temp_estate = webread(url_estate);
    for j = 1:19
        if ~isempty(temp_estate.indvdLandPrices.field)
            break;
        else
            url_estate = strcat(baseurl_estate,key,'&pnu=',stn_data.pnu(i,1:end-j),'&numOfRows=', num_of_row,'&format=',format,'&stdrYear=',start_year);    
            temp_estate = urlread(url_estate);
            temp_estate = jsondecode(temp_estate);
        end
    end
    if j == 19
        fprintf("%d 에러발생",i)
        cnt = cnt+1;
    end 
    stn_estate(i,1) = temp_estate;
    clear -regexp ^temp
    i
end
if ~(cnt == 0)
    fprintf("%d 에러 횟수",cnt)
end
estate = arrayfun(@(x) x.indvdLandPrices.field(1).pblntfPclnd,stn_estate,'UniformOutput',false);
% stn_new = stn_data(1:100,:);
stn_data.estate = estate; 

2 个评论
显示无隐藏无

Angelo Yeo 2023-10-12

Can you share "stn_data" as "mat"?

YoungMin 2023-10-12

i upload stn_data mat file

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Answer 1

Angelo Yeo 2023-10-12

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2032179-webread-returns-empty-stucture-but-urlread-works#answer_1331324

在 MATLAB Online 中打开

save_before_estate.mat

The script below uses webread instead of urlread. The point here is to use weboptions and set the ContentType to text.

load("save_before_estate.mat")
key = 'ZgFJoT6d3VEh1qz%2Fv%2Bj6SFAuefvQF%2BlboVR1njEK%2B8LcYTYddXSFE57fmAukUXPovujQLo9Fy05EvPpaGpH0ag%3D%3D';
baseurl_estate = 'http://apis.data.go.kr/1611000/nsdi/IndvdLandPriceService/attr/getIndvdLandPriceAttr?ServiceKey=';
start_year = '2020';
format = 'json';
num_of_row = '20';
for i = 1:height(stn_data)
    url_estate = strcat(baseurl_estate,key, ...
        '&pnu=',stn_data.pnu(i,1:end),'&numOfRows=', num_of_row,'&format=',format,'&stdrYear=',start_year);    
    % temp_estate = urlread(url_estate)
    options = weboptions('ContentType','text'); % I found the API returns json in text format.
    temp_estate = webread(url_estate, options)
    temp_estate = jsondecode(temp_estate);
    for j = 1:19
        if ~isempty(temp_estate.indvdLandPrices.field)
            break;
        else
            url_estate = strcat(baseurl_estate,key,'&pnu=',stn_data.pnu(i,1:end-j),'&numOfRows=', num_of_row,'&format=',format,'&stdrYear=',start_year);    
            temp_estate = urlread(url_estate);
            temp_estate = jsondecode(temp_estate);
        end
    end
    if j == 19
        fprintf("%d 에러발생",i)
        cnt = cnt+1;
    end 
    stn_estate(i,1) = temp_estate;
    clear -regexp ^temp
    i
end