[{"data":1,"prerenderedAt":1253},["ShallowReactive",2],{"doc:\u002Fautomating-reporting-workflows\u002Fgenerating-excel-reports-from-templates\u002Fpopulate-excel-template-without-losing-formatting":3,"surround:\u002Fautomating-reporting-workflows\u002Fgenerating-excel-reports-from-templates\u002Fpopulate-excel-template-without-losing-formatting":1245},{"id":4,"title":5,"body":6,"description":1236,"extension":1237,"meta":1238,"navigation":142,"path":1239,"seo":1240,"stem":1243,"__hash__":1244},"docs\u002Fautomating-reporting-workflows\u002Fgenerating-excel-reports-from-templates\u002Fpopulate-excel-template-without-losing-formatting\u002Findex.md","Populate an Excel Template Without Losing Formatting",{"type":7,"value":8,"toc":1221},"minimark",[9,29,34,62,70,84,87,389,396,402,415,531,545,549,554,656,663,667,670,816,835,839,846,1012,1015,1019,1105,1109,1112,1116,1125,1146,1163,1172,1176,1190,1194,1217],[10,11,12,13,17,18,23,24,28],"p",{},"The promise of a template is that its formatting is permanent — you fill in numbers and the fonts, fills, borders, number formats, and print layout come along for free. Whether that promise holds depends entirely on ",[14,15,16],"em",{},"how"," you write the data. This guide, a companion to ",[19,20,22],"a",{"href":21},"\u002Fautomating-reporting-workflows\u002Fgenerating-excel-reports-from-templates\u002F","Generating Excel Reports from Templates",", is about preservation: the one Python approach that keeps formatting, the one that destroys it, and precisely what ",[25,26,27],"code",{},"openpyxl"," does and does not carry through a round-trip.",[30,31,33],"h2",{"id":32},"prerequisites-and-install","Prerequisites and install",[35,36,41],"pre",{"className":37,"code":38,"language":39,"meta":40,"style":40},"language-bash shiki shiki-themes github-light github-dark","pip install openpyxl pandas\n","bash","",[25,42,43],{"__ignoreMap":40},[44,45,48,52,56,59],"span",{"class":46,"line":47},"line",1,[44,49,51],{"class":50},"sScJk","pip",[44,53,55],{"class":54},"sZZnC"," install",[44,57,58],{"class":54}," openpyxl",[44,60,61],{"class":54}," pandas\n",[30,63,65,66,69],{"id":64},"why-pandasto_excel-destroys-template-styling","Why ",[25,67,68],{},"pandas.to_excel"," destroys template styling",[10,71,72,75,76,79,80,83],{},[25,73,74],{},"pandas.to_excel(path)"," is built to ",[14,77,78],{},"serialize a DataFrame",", not to ",[14,81,82],{},"edit a file",". Even when the target path already exists, pandas does not open and patch it — it constructs a new worksheet and writes a plain grid of values and column headers. Every style your template carried is gone: the title banner, the header fill, merged cells, borders, conditional formatting, the print area, the totals formula.",[10,85,86],{},"The demonstration below makes the loss visible. We build a styled template, round-trip it through pandas, and check the header cell's fill:",[35,88,92],{"className":89,"code":90,"language":91,"meta":40,"style":40},"language-python shiki shiki-themes github-light github-dark","from openpyxl import Workbook, load_workbook\nfrom openpyxl.styles import Font, PatternFill\nimport pandas as pd\n\n# A styled template\nwb = Workbook()\nws = wb.active\nws[\"A1\"] = \"Region\"\nws[\"A1\"].font = Font(bold=True, color=\"FFFFFF\")\nws[\"A1\"].fill = PatternFill(\"solid\", fgColor=\"4472C4\")\nws[\"A2\"] = \"North\"\nwb.save(\"styled.xlsx\")\n\n# Round-trip through pandas\ndf = pd.read_excel(\"styled.xlsx\")\ndf.to_excel(\"via_pandas.xlsx\", index=False)\n\n# Inspect the result\ncheck = load_workbook(\"via_pandas.xlsx\")[\"Sheet1\"][\"A1\"]\nprint(\"Fill after pandas:\", check.fill.fgColor.rgb)   # 00000000 — styling lost\n","python",[25,93,94,110,123,137,144,151,163,174,191,230,260,275,286,291,297,312,333,338,344,371],{"__ignoreMap":40},[44,95,96,100,104,107],{"class":46,"line":47},[44,97,99],{"class":98},"szBVR","from",[44,101,103],{"class":102},"sVt8B"," openpyxl ",[44,105,106],{"class":98},"import",[44,108,109],{"class":102}," Workbook, load_workbook\n",[44,111,113,115,118,120],{"class":46,"line":112},2,[44,114,99],{"class":98},[44,116,117],{"class":102}," openpyxl.styles ",[44,119,106],{"class":98},[44,121,122],{"class":102}," Font, PatternFill\n",[44,124,126,128,131,134],{"class":46,"line":125},3,[44,127,106],{"class":98},[44,129,130],{"class":102}," pandas ",[44,132,133],{"class":98},"as",[44,135,136],{"class":102}," pd\n",[44,138,140],{"class":46,"line":139},4,[44,141,143],{"emptyLinePlaceholder":142},true,"\n",[44,145,147],{"class":46,"line":146},5,[44,148,150],{"class":149},"sJ8bj","# A styled template\n",[44,152,154,157,160],{"class":46,"line":153},6,[44,155,156],{"class":102},"wb ",[44,158,159],{"class":98},"=",[44,161,162],{"class":102}," Workbook()\n",[44,164,166,169,171],{"class":46,"line":165},7,[44,167,168],{"class":102},"ws ",[44,170,159],{"class":98},[44,172,173],{"class":102}," wb.active\n",[44,175,177,180,183,186,188],{"class":46,"line":176},8,[44,178,179],{"class":102},"ws[",[44,181,182],{"class":54},"\"A1\"",[44,184,185],{"class":102},"] ",[44,187,159],{"class":98},[44,189,190],{"class":54}," \"Region\"\n",[44,192,194,196,198,201,203,206,210,212,216,219,222,224,227],{"class":46,"line":193},9,[44,195,179],{"class":102},[44,197,182],{"class":54},[44,199,200],{"class":102},"].font ",[44,202,159],{"class":98},[44,204,205],{"class":102}," Font(",[44,207,209],{"class":208},"s4XuR","bold",[44,211,159],{"class":98},[44,213,215],{"class":214},"sj4cs","True",[44,217,218],{"class":102},", ",[44,220,221],{"class":208},"color",[44,223,159],{"class":98},[44,225,226],{"class":54},"\"FFFFFF\"",[44,228,229],{"class":102},")\n",[44,231,233,235,237,240,242,245,248,250,253,255,258],{"class":46,"line":232},10,[44,234,179],{"class":102},[44,236,182],{"class":54},[44,238,239],{"class":102},"].fill ",[44,241,159],{"class":98},[44,243,244],{"class":102}," PatternFill(",[44,246,247],{"class":54},"\"solid\"",[44,249,218],{"class":102},[44,251,252],{"class":208},"fgColor",[44,254,159],{"class":98},[44,256,257],{"class":54},"\"4472C4\"",[44,259,229],{"class":102},[44,261,263,265,268,270,272],{"class":46,"line":262},11,[44,264,179],{"class":102},[44,266,267],{"class":54},"\"A2\"",[44,269,185],{"class":102},[44,271,159],{"class":98},[44,273,274],{"class":54}," \"North\"\n",[44,276,278,281,284],{"class":46,"line":277},12,[44,279,280],{"class":102},"wb.save(",[44,282,283],{"class":54},"\"styled.xlsx\"",[44,285,229],{"class":102},[44,287,289],{"class":46,"line":288},13,[44,290,143],{"emptyLinePlaceholder":142},[44,292,294],{"class":46,"line":293},14,[44,295,296],{"class":149},"# Round-trip through pandas\n",[44,298,300,303,305,308,310],{"class":46,"line":299},15,[44,301,302],{"class":102},"df ",[44,304,159],{"class":98},[44,306,307],{"class":102}," pd.read_excel(",[44,309,283],{"class":54},[44,311,229],{"class":102},[44,313,315,318,321,323,326,328,331],{"class":46,"line":314},16,[44,316,317],{"class":102},"df.to_excel(",[44,319,320],{"class":54},"\"via_pandas.xlsx\"",[44,322,218],{"class":102},[44,324,325],{"class":208},"index",[44,327,159],{"class":98},[44,329,330],{"class":214},"False",[44,332,229],{"class":102},[44,334,336],{"class":46,"line":335},17,[44,337,143],{"emptyLinePlaceholder":142},[44,339,341],{"class":46,"line":340},18,[44,342,343],{"class":149},"# Inspect the result\n",[44,345,347,350,352,355,357,360,363,366,368],{"class":46,"line":346},19,[44,348,349],{"class":102},"check ",[44,351,159],{"class":98},[44,353,354],{"class":102}," load_workbook(",[44,356,320],{"class":54},[44,358,359],{"class":102},")[",[44,361,362],{"class":54},"\"Sheet1\"",[44,364,365],{"class":102},"][",[44,367,182],{"class":54},[44,369,370],{"class":102},"]\n",[44,372,374,377,380,383,386],{"class":46,"line":373},20,[44,375,376],{"class":214},"print",[44,378,379],{"class":102},"(",[44,381,382],{"class":54},"\"Fill after pandas:\"",[44,384,385],{"class":102},", check.fill.fgColor.rgb)   ",[44,387,388],{"class":149},"# 00000000 — styling lost\n",[10,390,391,392,395],{},"The header fill comes back as the default ",[25,393,394],{},"00000000",". Pandas rebuilt the sheet from scratch.",[30,397,65,399,401],{"id":398},"why-openpyxl-load-and-edit-keeps-formatting",[25,400,27],{}," load-and-edit keeps formatting",[10,403,404,406,407,410,411,414],{},[25,405,27],{},"'s ",[25,408,409],{},"load_workbook()"," parses the workbook's actual XML and hands you the real cells, with their styles attached. When you assign ",[25,412,413],{},"cell.value",", you change one thing — the value — and leave the style record alone. Save, and every untouched style is written straight back out. The same template, edited in place:",[35,416,418],{"className":89,"code":417,"language":91,"meta":40,"style":40},"from openpyxl import load_workbook\n\nwb = load_workbook(\"styled.xlsx\")    # the styled template from above\nws = wb.active\n\nws[\"A2\"] = \"South\"                   # change the value only\n\nwb.save(\"via_openpyxl.xlsx\")\n\ncheck = load_workbook(\"via_openpyxl.xlsx\")[\"Sheet\"][\"A1\"]\nprint(\"Fill after openpyxl:\", check.fill.fgColor.rgb)   # 004472C4 — preserved\n",[25,419,420,431,435,451,459,463,479,483,492,496,517],{"__ignoreMap":40},[44,421,422,424,426,428],{"class":46,"line":47},[44,423,99],{"class":98},[44,425,103],{"class":102},[44,427,106],{"class":98},[44,429,430],{"class":102}," load_workbook\n",[44,432,433],{"class":46,"line":112},[44,434,143],{"emptyLinePlaceholder":142},[44,436,437,439,441,443,445,448],{"class":46,"line":125},[44,438,156],{"class":102},[44,440,159],{"class":98},[44,442,354],{"class":102},[44,444,283],{"class":54},[44,446,447],{"class":102},")    ",[44,449,450],{"class":149},"# the styled template from above\n",[44,452,453,455,457],{"class":46,"line":139},[44,454,168],{"class":102},[44,456,159],{"class":98},[44,458,173],{"class":102},[44,460,461],{"class":46,"line":146},[44,462,143],{"emptyLinePlaceholder":142},[44,464,465,467,469,471,473,476],{"class":46,"line":153},[44,466,179],{"class":102},[44,468,267],{"class":54},[44,470,185],{"class":102},[44,472,159],{"class":98},[44,474,475],{"class":54}," \"South\"",[44,477,478],{"class":149},"                   # change the value only\n",[44,480,481],{"class":46,"line":165},[44,482,143],{"emptyLinePlaceholder":142},[44,484,485,487,490],{"class":46,"line":176},[44,486,280],{"class":102},[44,488,489],{"class":54},"\"via_openpyxl.xlsx\"",[44,491,229],{"class":102},[44,493,494],{"class":46,"line":193},[44,495,143],{"emptyLinePlaceholder":142},[44,497,498,500,502,504,506,508,511,513,515],{"class":46,"line":232},[44,499,349],{"class":102},[44,501,159],{"class":98},[44,503,354],{"class":102},[44,505,489],{"class":54},[44,507,359],{"class":102},[44,509,510],{"class":54},"\"Sheet\"",[44,512,365],{"class":102},[44,514,182],{"class":54},[44,516,370],{"class":102},[44,518,519,521,523,526,528],{"class":46,"line":262},[44,520,376],{"class":214},[44,522,379],{"class":102},[44,524,525],{"class":54},"\"Fill after openpyxl:\"",[44,527,385],{"class":102},[44,529,530],{"class":149},"# 004472C4 — preserved\n",[10,532,533,534],{},"The fill survives because you never touched it. This is the whole technique: ",[535,536,537,538,540,541,544],"strong",{},"write only ",[25,539,413],{},", leave ",[25,542,543],{},"cell"," styling untouched.",[30,546,548],{"id":547},"what-openpyxl-preserves-and-what-it-can-drop","What openpyxl preserves — and what it can drop",[10,550,551,553],{},[25,552,27],{}," is reliable for cell-level formatting and less so for some embedded objects. Know the boundary before you build a pipeline on it:",[555,556,557,571],"table",{},[558,559,560],"thead",{},[561,562,563,567],"tr",{},[564,565,566],"th",{},"Workbook feature",[564,568,570],{"align":569},"center","Survives load → edit → save?",[572,573,574,583,590,597,604,611,619,626,633,641,648],"tbody",{},[561,575,576,580],{},[577,578,579],"td",{},"Fonts, fills, borders, alignment",[577,581,582],{"align":569},"yes",[561,584,585,588],{},[577,586,587],{},"Number formats",[577,589,582],{"align":569},[561,591,592,595],{},[577,593,594],{},"Merged cells",[577,596,582],{"align":569},[561,598,599,602],{},[577,600,601],{},"Column widths \u002F row heights",[577,603,582],{"align":569},[561,605,606,609],{},[577,607,608],{},"Formulas (as strings, recalced by Excel)",[577,610,582],{"align":569},[561,612,613,616],{},[577,614,615],{},"Conditional formatting",[577,617,618],{"align":569},"usually — verify",[561,620,621,624],{},[577,622,623],{},"Data validation (dropdowns)",[577,625,618],{"align":569},[561,627,628,631],{},[577,629,630],{},"Print area, page setup, freeze panes",[577,632,582],{"align":569},[561,634,635,638],{},[577,636,637],{},"Charts",[577,639,640],{"align":569},"usually preserved in current versions; older versions could drop them",[561,642,643,646],{},[577,644,645],{},"Images",[577,647,640],{"align":569},[561,649,650,653],{},[577,651,652],{},"Pivot tables \u002F pivot caches",[577,654,655],{"align":569},"may be dropped",[10,657,658,659,662],{},"The practical rule: ",[535,660,661],{},"write only data cells, then re-save",", and keep templates focused on layout and formulas rather than pivots and exotic objects. Always open one generated file in Excel before trusting the pipeline, especially if the template carries charts, images, or pivots.",[30,664,666],{"id":665},"set-the-value-without-touching-the-style","Set the value without touching the style",[10,668,669],{},"The reason in-place editing preserves formatting is that value and style are separate attributes on a cell. Assigning the value never mutates the style:",[35,671,673],{"className":89,"code":672,"language":91,"meta":40,"style":40},"from openpyxl import load_workbook\n\nwb = load_workbook(\"styled.xlsx\")\nws = wb.active\n\ncell = ws[\"A1\"]\nbefore = cell.font.bold\ncell.value = \"Territory\"     # value changes...\nafter = cell.font.bold       # ...style does not\n\nprint(f\"bold before={before}, after={after}\")   # both True\nwb.save(\"retitled.xlsx\")\n",[25,674,675,685,689,701,709,713,727,737,750,763,767,807],{"__ignoreMap":40},[44,676,677,679,681,683],{"class":46,"line":47},[44,678,99],{"class":98},[44,680,103],{"class":102},[44,682,106],{"class":98},[44,684,430],{"class":102},[44,686,687],{"class":46,"line":112},[44,688,143],{"emptyLinePlaceholder":142},[44,690,691,693,695,697,699],{"class":46,"line":125},[44,692,156],{"class":102},[44,694,159],{"class":98},[44,696,354],{"class":102},[44,698,283],{"class":54},[44,700,229],{"class":102},[44,702,703,705,707],{"class":46,"line":139},[44,704,168],{"class":102},[44,706,159],{"class":98},[44,708,173],{"class":102},[44,710,711],{"class":46,"line":146},[44,712,143],{"emptyLinePlaceholder":142},[44,714,715,718,720,723,725],{"class":46,"line":153},[44,716,717],{"class":102},"cell ",[44,719,159],{"class":98},[44,721,722],{"class":102}," ws[",[44,724,182],{"class":54},[44,726,370],{"class":102},[44,728,729,732,734],{"class":46,"line":165},[44,730,731],{"class":102},"before ",[44,733,159],{"class":98},[44,735,736],{"class":102}," cell.font.bold\n",[44,738,739,742,744,747],{"class":46,"line":176},[44,740,741],{"class":102},"cell.value ",[44,743,159],{"class":98},[44,745,746],{"class":54}," \"Territory\"",[44,748,749],{"class":149},"     # value changes...\n",[44,751,752,755,757,760],{"class":46,"line":193},[44,753,754],{"class":102},"after ",[44,756,159],{"class":98},[44,758,759],{"class":102}," cell.font.bold       ",[44,761,762],{"class":149},"# ...style does not\n",[44,764,765],{"class":46,"line":232},[44,766,143],{"emptyLinePlaceholder":142},[44,768,769,771,773,776,779,782,785,788,791,793,796,798,801,804],{"class":46,"line":262},[44,770,376],{"class":214},[44,772,379],{"class":102},[44,774,775],{"class":98},"f",[44,777,778],{"class":54},"\"bold before=",[44,780,781],{"class":214},"{",[44,783,784],{"class":102},"before",[44,786,787],{"class":214},"}",[44,789,790],{"class":54},", after=",[44,792,781],{"class":214},[44,794,795],{"class":102},"after",[44,797,787],{"class":214},[44,799,800],{"class":54},"\"",[44,802,803],{"class":102},")   ",[44,805,806],{"class":149},"# both True\n",[44,808,809,811,814],{"class":46,"line":277},[44,810,280],{"class":102},[44,812,813],{"class":54},"\"retitled.xlsx\"",[44,815,229],{"class":102},[10,817,818,821,822,218,825,218,828,831,832,834],{},[25,819,820],{},"cell.style"," is effectively read-mostly: it names a registered named-style and is not where you make ad-hoc tweaks. To restyle, set the specific attributes (",[25,823,824],{},"cell.font",[25,826,827],{},"cell.fill",[25,829,830],{},"cell.number_format",") rather than assigning to ",[25,833,820],{},". For most template work you set none of them — that is the point.",[30,836,838],{"id":837},"copy-a-style-to-a-new-cell-when-you-must-extend-a-region","Copy a style to a new cell when you must extend a region",[10,840,841,842,845],{},"Sometimes you add rows beyond the template's pre-styled block and want the new cells to match. Styles are shared, immutable objects, so copy with ",[25,843,844],{},"copy()"," before assigning, to avoid mutating the source cell's style by reference:",[35,847,849],{"className":89,"code":848,"language":91,"meta":40,"style":40},"from copy import copy\nfrom openpyxl import load_workbook\n\nwb = load_workbook(\"styled.xlsx\")\nws = wb.active\n\nsrc = ws[\"A2\"]               # a pre-styled data cell\ndst = ws[\"A3\"]               # a new row to match it\ndst.value = \"West\"\ndst.font = copy(src.font)\ndst.fill = copy(src.fill)\ndst.border = copy(src.border)\ndst.number_format = src.number_format   # number_format is a plain string\n\nwb.save(\"extended.xlsx\")\nprint(\"Copied style to A3\")\n",[25,850,851,863,873,877,889,897,901,918,935,945,955,965,975,988,992,1001],{"__ignoreMap":40},[44,852,853,855,858,860],{"class":46,"line":47},[44,854,99],{"class":98},[44,856,857],{"class":102}," copy ",[44,859,106],{"class":98},[44,861,862],{"class":102}," copy\n",[44,864,865,867,869,871],{"class":46,"line":112},[44,866,99],{"class":98},[44,868,103],{"class":102},[44,870,106],{"class":98},[44,872,430],{"class":102},[44,874,875],{"class":46,"line":125},[44,876,143],{"emptyLinePlaceholder":142},[44,878,879,881,883,885,887],{"class":46,"line":139},[44,880,156],{"class":102},[44,882,159],{"class":98},[44,884,354],{"class":102},[44,886,283],{"class":54},[44,888,229],{"class":102},[44,890,891,893,895],{"class":46,"line":146},[44,892,168],{"class":102},[44,894,159],{"class":98},[44,896,173],{"class":102},[44,898,899],{"class":46,"line":153},[44,900,143],{"emptyLinePlaceholder":142},[44,902,903,906,908,910,912,915],{"class":46,"line":165},[44,904,905],{"class":102},"src ",[44,907,159],{"class":98},[44,909,722],{"class":102},[44,911,267],{"class":54},[44,913,914],{"class":102},"]               ",[44,916,917],{"class":149},"# a pre-styled data cell\n",[44,919,920,923,925,927,930,932],{"class":46,"line":176},[44,921,922],{"class":102},"dst ",[44,924,159],{"class":98},[44,926,722],{"class":102},[44,928,929],{"class":54},"\"A3\"",[44,931,914],{"class":102},[44,933,934],{"class":149},"# a new row to match it\n",[44,936,937,940,942],{"class":46,"line":193},[44,938,939],{"class":102},"dst.value ",[44,941,159],{"class":98},[44,943,944],{"class":54}," \"West\"\n",[44,946,947,950,952],{"class":46,"line":232},[44,948,949],{"class":102},"dst.font ",[44,951,159],{"class":98},[44,953,954],{"class":102}," copy(src.font)\n",[44,956,957,960,962],{"class":46,"line":262},[44,958,959],{"class":102},"dst.fill ",[44,961,159],{"class":98},[44,963,964],{"class":102}," copy(src.fill)\n",[44,966,967,970,972],{"class":46,"line":277},[44,968,969],{"class":102},"dst.border ",[44,971,159],{"class":98},[44,973,974],{"class":102}," copy(src.border)\n",[44,976,977,980,982,985],{"class":46,"line":288},[44,978,979],{"class":102},"dst.number_format ",[44,981,159],{"class":98},[44,983,984],{"class":102}," src.number_format   ",[44,986,987],{"class":149},"# number_format is a plain string\n",[44,989,990],{"class":46,"line":293},[44,991,143],{"emptyLinePlaceholder":142},[44,993,994,996,999],{"class":46,"line":299},[44,995,280],{"class":102},[44,997,998],{"class":54},"\"extended.xlsx\"",[44,1000,229],{"class":102},[44,1002,1003,1005,1007,1010],{"class":46,"line":314},[44,1004,376],{"class":214},[44,1006,379],{"class":102},[44,1008,1009],{"class":54},"\"Copied style to A3\"",[44,1011,229],{"class":102},[10,1013,1014],{},"Better still, size the template's styled region for your largest run so you rarely need to copy styles at all.",[30,1016,1018],{"id":1017},"common-pitfalls","Common pitfalls",[555,1020,1021,1034],{},[558,1022,1023],{},[561,1024,1025,1028,1031],{},[564,1026,1027],{},"Symptom",[564,1029,1030],{},"Cause",[564,1032,1033],{},"Fix",[572,1035,1036,1056,1069,1083,1094],{},[561,1037,1038,1041,1046],{},[577,1039,1040],{},"All styling gone in the output",[577,1042,1043,1044],{},"Round-tripped through ",[25,1045,68],{},[577,1047,1048,1049,1051,1052,1055],{},"Use ",[25,1050,27],{}," ",[25,1053,1054],{},"load_workbook"," + edit cells in place",[561,1057,1058,1061,1064],{},[577,1059,1060],{},"New rows below the data block are unstyled",[577,1062,1063],{},"Template only styled its original region",[577,1065,1066,1068],{},[25,1067,844],{}," a styled cell's font\u002Ffill\u002Fborder onto the new cells",[561,1070,1071,1074,1077],{},[577,1072,1073],{},"Editing one cell's style changed another",[577,1075,1076],{},"Assigned a shared style object by reference",[577,1078,1079,1080,1082],{},"Wrap with ",[25,1081,844],{}," before assigning",[561,1084,1085,1088,1091],{},[577,1086,1087],{},"Conditional formatting missing after save",[577,1089,1090],{},"Rare openpyxl edge case or a stale version",[577,1092,1093],{},"Upgrade openpyxl; open the file in Excel and verify the rules",[561,1095,1096,1099,1102],{},[577,1097,1098],{},"Chart or pivot vanished",[577,1100,1101],{},"Older openpyxl dropped the object",[577,1103,1104],{},"Upgrade openpyxl; keep pivots\u002Fcharts minimal; verify a sample output",[30,1106,1108],{"id":1107},"a-note-on-verification","A note on verification",[10,1110,1111],{},"Preservation is \"usually\" reliable, not \"always.\" The cheap insurance is to open one generated workbook in Excel after any template or library change and confirm conditional formatting, data validation dropdowns, charts, and the print area all survived. Once verified for a given template and openpyxl version, the pipeline is dependable until one of those changes.",[30,1113,1115],{"id":1114},"frequently-asked-questions","Frequently asked questions",[10,1117,1118,1121,1122,1124],{},[535,1119,1120],{},"Can I use pandas at all in a template pipeline?","\nYes — for the data, not the writing. Build and transform your DataFrame with pandas, then hand the values to ",[25,1123,27],{}," cell by cell. Never let pandas write to the template file.",[10,1126,1127,1134,1135,1137,1138,1141,1142,1145],{},[535,1128,1129,1130,1133],{},"Does ",[25,1131,1132],{},"keep_vba=True"," affect formatting preservation?","\nIt is orthogonal. ",[25,1136,1132],{}," preserves the VBA macro project in ",[25,1139,1140],{},".xlsm","\u002F",[25,1143,1144],{},".xltm"," files; cell formatting is preserved by editing in place regardless. Use both for a macro-enabled template.",[10,1147,1148,1151,1152,1141,1155,1158,1159,1162],{},[535,1149,1150],{},"Why does my number show as text after editing?","\nYou likely assigned a string. Number formats apply to numeric values — assign an ",[25,1153,1154],{},"int",[25,1156,1157],{},"float"," (or ",[25,1160,1161],{},"datetime",") and the template's number format renders it correctly.",[10,1164,1165,1168,1169,1171],{},[535,1166,1167],{},"Is there a faster bulk way that still preserves styles?","\nNo streaming shortcut preserves an existing template's styles — those modes write fresh files. For template injection, in-place ",[25,1170,1054],{}," editing is the correct and only style-safe path.",[30,1173,1175],{"id":1174},"conclusion","Conclusion",[10,1177,1178,1179,406,1181,1183,1184,1186,1187,1189],{},"Formatting is preserved when you treat the template as a file to patch, not a sheet to regenerate. ",[25,1180,27],{},[25,1182,1054],{}," hands you real cells with their styles attached; assign ",[25,1185,413],{}," and the styling rides through the save untouched. ",[25,1188,68],{}," rebuilds the sheet and discards all of it. Know the small set of objects openpyxl can drop — pivots and, on older versions, charts and images — write only data cells, and verify one output in Excel after any change.",[30,1191,1193],{"id":1192},"where-to-go-next","Where to go next",[1195,1196,1197,1203,1210],"ul",{},[1198,1199,1200,1202],"li",{},[19,1201,22],{"href":21}," — the cluster overview tying preservation into the full template pipeline.",[1198,1204,1205,1209],{},[19,1206,1208],{"href":1207},"\u002Fautomating-reporting-workflows\u002Fgenerating-excel-reports-from-templates\u002Ffill-excel-template-with-python-openpyxl\u002F","Fill an Excel Template with Python and openpyxl"," — the step-by-step mechanics of writing the data cells you preserve formatting around.",[1198,1211,1212,1216],{},[19,1213,1215],{"href":1214},"\u002Fformatting-and-charting-excel-reports-with-python\u002Fstyling-excel-cells-with-openpyxl\u002F","Styling Excel Cells with openpyxl"," — how fonts, fills, and borders are constructed when you do build styling in code.",[1218,1219,1220],"style",{},"html pre.shiki code .sScJk, html code.shiki .sScJk{--shiki-default:#6F42C1;--shiki-dark:#B392F0}html pre.shiki code .sZZnC, html code.shiki .sZZnC{--shiki-default:#032F62;--shiki-dark:#9ECBFF}html .default .shiki span {color: var(--shiki-default);background: var(--shiki-default-bg);font-style: var(--shiki-default-font-style);font-weight: var(--shiki-default-font-weight);text-decoration: var(--shiki-default-text-decoration);}html .shiki span {color: var(--shiki-default);background: var(--shiki-default-bg);font-style: var(--shiki-default-font-style);font-weight: var(--shiki-default-font-weight);text-decoration: var(--shiki-default-text-decoration);}html .dark .shiki span {color: var(--shiki-dark);background: var(--shiki-dark-bg);font-style: var(--shiki-dark-font-style);font-weight: var(--shiki-dark-font-weight);text-decoration: var(--shiki-dark-text-decoration);}html.dark .shiki span {color: var(--shiki-dark);background: var(--shiki-dark-bg);font-style: var(--shiki-dark-font-style);font-weight: var(--shiki-dark-font-weight);text-decoration: var(--shiki-dark-text-decoration);}html pre.shiki code .szBVR, html code.shiki .szBVR{--shiki-default:#D73A49;--shiki-dark:#F97583}html pre.shiki code .sVt8B, html code.shiki .sVt8B{--shiki-default:#24292E;--shiki-dark:#E1E4E8}html pre.shiki code .sJ8bj, html code.shiki .sJ8bj{--shiki-default:#6A737D;--shiki-dark:#6A737D}html pre.shiki code .s4XuR, html code.shiki .s4XuR{--shiki-default:#E36209;--shiki-dark:#FFAB70}html pre.shiki code .sj4cs, html code.shiki .sj4cs{--shiki-default:#005CC5;--shiki-dark:#79B8FF}",{"title":40,"searchDepth":112,"depth":112,"links":1222},[1223,1224,1226,1228,1229,1230,1231,1232,1233,1234,1235],{"id":32,"depth":112,"text":33},{"id":64,"depth":112,"text":1225},"Why pandas.to_excel destroys template styling",{"id":398,"depth":112,"text":1227},"Why openpyxl load-and-edit keeps formatting",{"id":547,"depth":112,"text":548},{"id":665,"depth":112,"text":666},{"id":837,"depth":112,"text":838},{"id":1017,"depth":112,"text":1018},{"id":1107,"depth":112,"text":1108},{"id":1114,"depth":112,"text":1115},{"id":1174,"depth":112,"text":1175},{"id":1192,"depth":112,"text":1193},"Why pandas.to_excel destroys template styling and openpyxl preserves it — what load_workbook keeps, what it can drop, and how to set values without touching styles.","md",{},"\u002Fautomating-reporting-workflows\u002Fgenerating-excel-reports-from-templates\u002Fpopulate-excel-template-without-losing-formatting",{"title":1241,"description":1242},"Populate Excel Template, Keep Formatting","Keep your Excel template's styles intact in Python: use openpyxl load_workbook to edit values in place, learn what survives the round-trip, and copy styles when needed.","automating-reporting-workflows\u002Fgenerating-excel-reports-from-templates\u002Fpopulate-excel-template-without-losing-formatting\u002Findex","-qVrU-ySDSHkhwCCF0b-u7jw9AWEsGKGZhlmCU8JPr4",[1246,1249],{"title":1208,"path":1247,"stem":1248,"children":-1},"\u002Fautomating-reporting-workflows\u002Fgenerating-excel-reports-from-templates\u002Ffill-excel-template-with-python-openpyxl","automating-reporting-workflows\u002Fgenerating-excel-reports-from-templates\u002Ffill-excel-template-with-python-openpyxl\u002Findex",{"title":1250,"path":1251,"stem":1252,"children":-1},"Scheduling Python Excel Scripts with Cron","\u002Fautomating-reporting-workflows\u002Fscheduling-python-excel-scripts-with-cron","automating-reporting-workflows\u002Fscheduling-python-excel-scripts-with-cron\u002Findex",1781773160963]